1. The most likely diagnosis is:
A 24-year-old woman presents with an asymptomatic nodule extant on her lip for more than a year. When the lesion first manifested, it ruptured with slight trauma, drained a clear liquid, then disappeared, only to form again weeks later. But for the past six months, the nodule has gotten larger. The patient cannot remember any trauma to the area. She was not pregnant at the time of the initial appearance.
The most likely diagnosis is:
A) Traumatic fibroma B) Pyogenic granuloma C) Fordyce's granules D) Mucocele

2. A 55-year-old man presents with darkening of his facial skin, which he reports has been worsening during the past two years. He did not notice the discoloration until friends pointed it out, and he is otherwise asymptomatic. History reveals that the patient has been taking minocycline for several years for treatment of rosacea. Otherwise, he is in good health; findings from a recent physical examination and related blood tests were all normal. Nonetheless, he requested and received a referral to dermatology.
Examination of the skin shows definite bilateral, patchy, slate-colored macular areas of hyperpigmentation, particularly on the sides of the face. There is no epidermal disturbance (ie, scale, broken skin, papularity) in these areas. Examination of his ears, teeth, gums, and sclerae reveal no abnormality.
A) Ochronosis B) Hemochromatosis C) Drug reaction to minocycline D) Addison's disease
The correct answer is a drug reaction to minocycline (choice "c"), which is a known cause of this type of hyperpigmentation. Unlike the presentation seen in this patient, this relatively common reaction can also involve teeth, gums, sclerae, nails, or even bone. Affected patients have usually ingested at least 50 g of minocycline, although a reaction may occur after a smaller dose. The pigment contains iron and is located in dermal macrophages. Discoloration gradually clears following discontinuation of drug use (as occurred in this patient).
In addition to minocycline, a number of other drugs can cause blue-gray dyspigmentation of the skin and mucosae. These include amiodarone, bleomycin, busulfan, chlorquine, chlorpromazine, clofazimine, trifluoperazine, thioridazine, zidovudine, and silver-containing drugs. When necessary, iron stains of biopsied skin can aid in determining the exact cause.
Ochronosis (choice "a") is usually secondary to alkaptonuria, which itself is characterized by the accumulation of homogentisic acid (HGA), caused by a very rare, inborn error of tyrosine metabolism. The resulting polymerization of HGA manifests as ochronosis. The brownish-black pigment is deposited in connective tissue, sclerae, and skin (particularly the ears). Had our patient's problem not resolved with cessation of minocycline, further investigation (starting with a check of urine HGA levels) would have been indicated.
Hemochromatosis (choice "b"), also known as bronzed diabetes, is inherited as an autosomal recessive disease, and represents abnormal absorption of iron that is then deposited in the skin, liver, heart, pancreas, and endocrine organs, including the pituitary. The brown to slate hyperpigmentation associated with it is the result of melanin and is part of a classic triad that includes cirrhosis and diabetes. With his unremarkable history, physical examination, and laboratory tests, our patient was unlikely to suffer from this disease.
Addison's disease (choice "d") is caused by adrenal insufficiency, itself idiopathic for the most part, but assumed to be of autoimmune origin. It too can lead to generalized hyperpigmentation, which ranges from brown to black. Our patient's presumed good state of health made this an unlikely choice, but as with the other incorrect choices, Addison's disease would have to be considered if the problem did not resolve with cessation of the offending drug.

3. A 27-year-old woman is referred to dermatology for evaluation of a recurrent "staph infection of the eye," always manifesting in the same location (just below the right eye), always tingling and itching, with slight pain, and always resolving in 10 to 14 days. She has experienced premonitory symptoms with each episode, at which point she has sought medical evaluation and been given oral antibiotics. While the treatment seems effective, the problem persists. She is an otherwise healthy individual and is not prone to skin infections in general, although she has had cold sores.
Examination reveals a collection of papulovesicular lesions on an erythematous base below the right eye. There is no adenopathy in the area, and the eye itself is not involved, nor has it been during past episodes
A) Recurrent staph infection B) Recurrent shingles (varicella-zoster virus) C) Contact dermatitis D) Herpes simplex virus
The correct answer is herpex simplex virus (HSV; choice "d"). Culture confirmed the obvious clinical impression. HSV occurs most commonly on or around the lips but can be found almost anywhere on the face, ears, fingers, toes, and buttocks. Any treatment offered appears to be successful since each episode is self-limiting, so these lesions are often misdiagnosed as staph infection or shingles.
Recurrent staph infection (choice "a") is incorrect because there is no model of a staph infection (or other bacterial infection, for that matter) recurring in the same location or presenting with collections of vesicles. The positive herpes culture, of course, conclusively eliminated this possibility.
Shingles (choice "b") is unilateral in distribution and recurs in only 5% of cases. When it does recur, it tends to be much more florid than what is seen in this patient and more distressing in terms of symptoms.
Contact dermatitis (choice "c") could have explained this patient's complaint, but the natural history of multiple recurrences in a fixed location is far more suggestive of herpes.

4. A) Nummular eczema B) Tinea corporis C) Psoriasis D) Bowen's disease
70-year-old man is referred to dermatology for evaluation of "ringworm" on his legs and trunk, which has been unresponsive to topical and oral antifungal medications. The lesions initially manifested in the early fall and increased in number with the onset of winter. The patient owns no pets or livestock and has no contact with children or with the soil. He is immunocompetent and otherwise healthy. He uses his hot tub several times a week and likes to take long, hot showers. Family medical history is negative for skin diseases of any kind.
Examination shows approximately 20 round, uniformly and superficially scaly pinkish-brown papulosquamous lesions ranging from 1.0 to 2.8 cm on the patient's legs (shown), buttocks, and trunk. KOH examination of these lesions is negative. Elsewhere on his body, his skin is extremely dry, but his elbows, knees, nails, and scalp are otherwise normal in appearance
A) Nummular eczema B) Tinea corporis C) Psoriasis D) Bowen's disease
The correct answer is nummular eczema (NE; choice "a"), an exceedingly common condition that favors the older patient with dry skin, made worse by low winter humidity, long hot showers, and/or hot tubbing. Many of these patients have always had dry skin. However, as they age, their xerosis worsens, as does their intolerance of cold; this leads them to seek warmth in a number of ways (eg, by wearing warmer clothes, leaving the thermostat on high, or using hot tubs) -- all of which serve to dry the skin even more.

5. A 24-year-old woman is referred to dermatology for evaluation of lesions that have been present on her face for three days. She reports several prior outbreaks of a similar nature, each of which lasted 10 to 12 days. The patient reports symptoms of tingling and itching, with a small amount of pain in the lesions -- symptoms that are identical to previous attacks. Although the patient has a history of chickenpox as a child -- and even though she feels fine -- her primary care provider initially made a diagnosis of chickenpox, then changed the diagnosis to shingles. Previous attacks were treated with a five-day course of valacyclovir, and the lesions gradually resolved, only to reappear later. The patient's medical history is unremarkable except for having atopic dermatitis.
Examination shows the lesions to be discrete 3- to 5-mm vesicles, many with umbilicated centers, distributed evenly over the inferior one third of the face and upper neck.
A) Staph infection B) Eczema herpeticum, or Kaposi's varicelliform eruption C) Varicella D) Molluscum contagiosum
The correct answer is eczema herpeticum, or Kaposi's varicelliform eruption (KVE; choice "b"). This unusual (but by no means rare) condition represents disseminated herpes simplex infection superimposed on preexisting atopic dermatitis. It is a diagnosis almost unknown outside the dermatology office.
Atopic dermatitis patients are exceptionally susceptible to cutaneous infections (viral, fungal, or bacterial). In this case, culture confirmed the herpetic nature of the process. Treatment was with prophylactic valacyclovir, 500 mg/d, in view of the chronic nature of the problem.
Staph infection (choice "a") is unlikely to recur in the same location and is even less likely to be accompanied by symptoms of tingling and itch.
Varicella (choice "c"), or chickenpox, is caused by a herpetic virus, but immunocompetent adults would have it in multiple locations and, more importantly, would likely be ill. The recurrent nature of her problem and previous history of having had chickenpox as a child both speak loudly against this diagnosis.
These lesions are inconsistent with molluscum contagiosum (choice "d"), although both are viral in origin and can present with umbilicated centers. The latter are fixed, firm, waxy papules, not transient vesicles (fluid-filled papules), as seen in this patient.
Education of patients with atopic dermatitis and their families regarding the need to avoid those with herpes labialis ("cold sore") is important. Remember, too, that the patient with an initial attack of KVE can experience fever, malaise, and flu-like symptoms.

6. For three weeks, a 22-year-old woman has had a rash, which has persisted over a good part of her body despite application of topical antifungal and steroid creams. She says that the rash started with one large, round, scaly lesion on her lower abdomen, followed within a day or two by the appearance of hundreds of smaller but similar lesions that are still manifesting after three weeks. The patient reports no other symptoms, but she is greatly concerned nonetheless. She denies fever and malaise and is otherwise healthy, and she has a monogamous relationship with her husband.
On examination, the pinkish tan lesions are found to be papulosquamous, predominantly annular, with a curious fine scale in the center. They appear primarily on truncal skin, sparing the face, palms, soles, and lower legs. KOH examination of the scale is negative.
A) Pityriasis rosea B) Tinea versicolor C) Tinea corporis D) Secondary syphilis
The correct answer is pityriasis rosea (choice "a"). This condition, commonly seen in the second and third decades of life, is believed to be caused by a virus, although none has ever been identified. It typically lasts six to nine weeks, which may be distressing to the patient. About 40% of the time, it begins with a large (3- to 6-cm), round to oval, pinkish tan, papulosquamous lesion (known as a herald patch) that can vary in distribution but seems to favor the anterior trunk. Within a day or so, smaller versions of this herald patch begin to appear on truncal skin, particularly the back and abdomen, as well as on the arms and neck. These smaller lesions tend to be oval, with their long axes running parallel to skin tension lines. They typically range in size from 0.3 to 3.0 cm. The rash rarely spreads above the neck and never affects the palms or soles. Pityriasis rosea, though pruritic, is notable for its lack of symptoms, particularly given how widespread and striking it can appear. Its differential diagnosis includes guttate psoriasis, in addition to the conditions listed below. But the appearance of the central scale (termed centripetal) contrasts sharply with the uniform scale of psoriasis and is virtually pathognomonic for pityriasis rosea.

7. A 40-year-old woman presents with a highly debilitating hand rash that started six weeks prior to this visit. She was referred by her primary care provider after he treated her with oral antibiotics (cephalexin 500 mg four times a day for 10 days) to no good effect. The patient is otherwise in good health, with no history of skin diseases or other serious illness. She has, however, been under more stress than she is accustomed to.
The examination shows a bilateral palmar eruption characterized by discrete and coalescent pustules and erosions, producing raw skin in the central palm of both hands. There are no palpable nodes in either epitrochlear or axillary locations, and there is little if any redness around the rash. Examination elsewhere reveals a few 1- to 2-cm papulosquamous lesions on the legs; the patient reports that these appeared at about the same time as the palmar eruption. Moreover, there are pits in three of 10 fingernail plates, and a curious pink rash without scale in the upper intergluteal area. The feet are clear.
A) Chronic staph infection B) Contact dermatitis C) Psoriasis D) Chronic fungal infection
The correct answer is psoriasis (choice "c"), which can present as an acute pustular eruption of the palms and/or soles. As in this case, corroboration for the diagnosis can be found by examining other common areas of involvement, especially nails, scalp, elbows, knees, and intergluteal skin (too moist and with too much friction to allow any scale to accumulate). In about one third of such cases, there is a positive family history of psoriasis, which also lends credence to the diagnosis. The history of a sudden increase in stress is also common in cases like this.

8. The best next step is to:
The worried parents of a 5-year-old boy bring him for evaluation of a lesion present on the scalp since he was 1 year old; with the exception of slight growth in size, the lesion remained unchanged as the child grew. There is no family history of skin cancer and the child is immunocompetent. He has had no sunburns in his life.
Examination reveals a round, 5-mm hair-bearing macule in the temporal scalp. A closer look shows that the lesion has a tan center and a slightly darker ring of brown pigment around the periphery. There are no nodes palpable in the area, and the child's type II skin is otherwise free of remarkable lesions.
The best next step is to:
a) Reassure the parents that the lesion is safe and they can ignore it
b) Recommend removal of the lesion
c) Tell the parents it's very likely safe but advise them to watch for changes in shape, color, and texture
d) Tell the parents it's a type of dysplastic nevus and could turn into melanoma
The correct answer is to tell them it's safe but to watch for changes (choice "c"). This particular lesion, called a nevus en cocarde, is quite common in the lateral scalps of children and has very little, if any, malignant potential. Its round, symmetrical shape, even borders, and small size are all reassuring of its benign nature.
Moreover, there are no other factors involved that might add to concern about any lesion, such as a family history of melanoma, excessive sun exposure, immunosuppression, or large numbers of skin lesions in general -- any one of which could tip the scales in favor of removal. The peripheral ring of pigment seen with this lesion often worries nondermatology providers, but actually should be a very reassuring sign, other things (eg, symmetry, border, color, diameter) being equal.
Telling the parents it's safe and they can ignore it (choice "a") is not a good option; even though this particular lesion appears quite safe, we definitely want to watch for changes, and we want to educate the parents as to exactly what to watch for.
Recommending removal (choice "b") is incorrect. Especially on a child, lesions shouldn't be removed without good reason to do so. There will always be parents who insist on removal and, if the child is willing, it has to be done. But if the decision is left to the provider, it should not be removed.
Telling the parents it's a type of dysplastic nevus (choice "d") is also incorrect. This lesion is benign and exhibits none of the features we might see with a dysplastic nevus. Moreover, dysplastic nevi have a very low potential to undergo malignant transformation. They are important because they need to be distinguished from melanoma and because their presence makes it more likely that the patient will eventually develop a melanoma in his or her lifetime.
Prognosis
Less than 2% of all melanomas occur in children younger than 12. Thus, the good news is that any lesion you see on a child is quite unlikely to turn into a melanoma. The bad news is that there will be a small number of such malignancies seen in children every year, so all lesions need to be examined carefully, taking into consideration the context in which they appear. It helps a great deal to know what common benign lesions one might see, and nevus en cocarde is one seen almost every day in a pediatric or dermatology practice. Parents and patients should be educated about the lifetime risk of developing a melanoma (which for this child is about one in 75).

9. A 45-year-old woman is referred to dermatology by her primary care provider for removal of cosmetically unacceptable lesions that have been present on her face, lips, neck, and arms for most of her life. She has been seen for them on a number of occasions, but the emphasis had always been on how to eliminate them rather than on determining their origin. The patient is otherwise healthy but has a family history of the lesions; a sibling has the same kind of lesions on her face, and her father, who also had an extensive history of gastrointestinal bleeds leading to a partial colectomy, had them as well. All three experienced excessive nosebleeds as children. The patient has no history of Raynaud's phenomenon or of esophageal complaints.
Examination reveals a collection of blood-red papules and telangiectases on the tongue, cheeks, chin, neck, sclerae, and (to a lesser extent) the fingertips. These are obviously vascular in origin, being blanchable and nontender. The skin examination is otherwise normal
A) Dermatoheliosis (sun damage) B) Spider angiomas C) Hereditary hemorrhagic telangiectasia D) CRST syndrome
The correct answer is hereditary hemorrhagic telangiectasia (HHT; choice "c"), originally named Osler-Weber-Rendu disease after its discoverers. HHT is an autosomal inherited disorder characterized by epistaxis, melena, atriovenous malformations, and fistulas, in addition to skin lesions like those seen on this patient. It is caused by a mutation of endoglin, a protein that binds endothelial cells, and is related to a chromosomal alteration of 9q3. As in this case, 80% of patients will have an abnormal family history.
Dermatoheliosis (choice "a") often involves the appearance of telangiectases, but they are confined to sun-exposed skin and are linear, not lesional as with HHT, so this is an incorrect choice.
Spider angiomas (choice "b") are in the differential with HHT but are generally solitary and look quite different (having a central pinpoint feeder vessel with "legs" coming off it radially). They have nothing to do with arteriopathy, so this is an incorrect choice.
phenomenon, sclerodactyly, and telangiectasia, manifests with vascular lesions sometimes indistinguishable from those seen in HHT. However, over the many years this patient has had her lesions, CRST would almost certainly have announced its presence with progression of signs and symptoms. As none of these are present in this patient, this choice is incorrect.
Treatment/Prognosis
As often happens in these cases, the patient's concern -- "How can I get rid of these?" -- becomes the provider's. What should have been asked was "Why does this patient have these lesions?" Unfortunately, the only way this diagnosis can be made is by knowing the differential, along with distinguishing historical and morphological features of its elements. In other words, a clinician who had never heard of HHT would not have a chance of diagnosing it.
This patient was referred to a dermatologist who was able to ablate these lesions with a 532-nm laser. But, more importantly, she was referred back to her primary care provider for follow-up for her HHT, which includes regular checks for blood in her stool, avoidance of nonsteroidal anti-inflammatory drugs, and regular checks for retinal bleeds by an ophthalmologist. Her internist will monitor her for signs of intracranial pathology, such as atriovenous malformations, fistulas, or bleeding.

10. The name of that lesion is:
A 14-year-old boy is brought in by his mother for evaluation of lesions present since age 6 months. The child is otherwise healthy and there is no history of skin disease in the family. The boy's pediatrician had suspected neurofibromatosis (NF), but since there was no family history of that malady and since the boy had not demonstrated any other signs of the disease, the decision had been made to wait and see what developed. But by now his mother is more concerned and has obtained a referral to dermatology.
Examination reveals eight lesions ranging in size from 3 to 10 cm. They are roughly oval and are located on the trunk and in the axillary areas. They are macular and uniformly light tan. No other stigmata of NF are seen, but the patient is referred to an ophthalmologist, who confirms the diagnosis of neurofibromatosis type 1 (NF1) based on the presence of a particular lesion in the patient's iris.
The name of that lesion is:
A) Janeway's lesion B) Darier's sign C) Gottron's papule D) Lisch nodule
E. Café Au Lait spot
The correct answer is the Lisch nodule (choice "d"), which is considered (other things being equal) confirmatory of NF1. Lisch nodules appear in about 95% of children with NF1 by age 10 and are thus useful in diagnosing cases like this. Slit lamp examination for Lisch nodules can be helpful.
NF1, formerly known as von Recklinghausen's disease, is an autosomal dominantly inherited condition found in about one in every 3,500 live births, but about 50% of cases are thought to be a result of spontaneous mutation. In addition to café-au-lait spots, NF1 is manifested by the appearance of hamartomas (Lisch nodules) in the iris, by axillary freckling (called Crowe's sign), and by the appearance after puberty of dermal and internal tumors called neurofibromas. While NF1 constitutes approximately 95% of all cases of NF, there is a neurofibromatosis type 2, which is characterized by bilateral acoustic neuromas instead of café-au-lait spots.
Janeway's lesion (choice "a") is the eponymic designation given to erythematous/hemorrhagic macules or nodules seen in the palms and soles in association with infective endocarditis and is thus incorrect. Darier's sign (choice "b") is the name given to the urticative flare experienced on stroking the lesions of urticaria pigmentosa and thus has nothing to do with NF. Gottron's papule (choice "c") refers to the papulosquamous eruption seen on the dorsal fingers in dermatomyositis and is also an incorrect choice.
Treatment/Prognosis
There is no treatment for NF1, but these patients still need genetic counseling and monitoring for the many complications of their disease, such as pheochromocytoma and other neurally derived tumors.

12. Crowe’s sign

13. A) Impetigo or other cutaneous bacterial infection
A 70-year-old woman presents for evaluation of a slightly sensitive erythematous patch of skin on her nose that has been present for more than a year. She reports that it has been slowly growing and that it is exacerbated by direct sun exposure. Because the lesion has persisted despite previous treatment for possible infection with oral and topical antibiotics and topical hydrocortisone 1% cream, her primary care provider referred her to dermatology. At this point, however, no medication has been applied to the lesion for months.
The patient is otherwise healthy and has no joint pain, fever, or malaise. She is not diabetic, and there is no history of trauma to the area. No other skin lesions or conditions are noted on examination.
The nose lesion is erythematous and nontender. It blanches with light pressure, and there is a faint amount of scale on its surface. There are no palpable nodes in the area
A 3-mm punch biopsy is performed, and it proves to be diagnostic. What is the most likely diagnosis?
A) Impetigo or other cutaneous bacterial infection
B) Discoid lupus erythematosus
C) Actinic keratosis
D) Contact dermatitis
The correct answer is "b," discoid lupus erythematosus (DLE), a condition commonly found on facial or other sun-exposed skin. Sunlight is a common trigger for DLE, which is considered an autoimmune disease.
Test results on this patient show no evidence for systemic lupus erythematosus (SLE), but this testing is definitely indicated; approximately 25% of systemic lupus patients will demonstrate signs of DLE, and 5% of DLE patients will eventually evolve to SLE.
Impetigo or other cutaneous bacterial infection (choice "a") is unlikely, given the lack of response to antibiotic therapy, absence of an entry wound, and lack of any special susceptibility to infection. Conditions associated with susceptibility include diabetes, chronic steroid therapy (eg, prednisone), other immunosuppressive therapy (eg, cyclosporine, methotrexate), HIV or other diseases involving a deficient immune system, and loss of regional nodes, as with surgical node dissection. Furthermore, with or without treatment, very few bacterial infections persist for longer than a year.
Actinic keratosis (choice "c") is not a bad choice, considering the patient's age, the advanced sun damage to her upper lip, and the history of sun exposure as an exacerbating factor.
Choice "d," contact dermatitis, would not persist for more than a year unless the offending substance had been applied repeatedly, which was not the case with this patient. This "treatment-becomes-the-problem" scenario is extremely common, especially with neomycin-containing topical preparations. Patients should always be asked about such treatment.
There is a tendency for some providers to treat everything that is red as an infection—even when all evidence points elsewhere. One doesn't just "get" an infection in a specific place on the nose; there are reasons why such things appear (as explained above). However, some providers may not be familiar with other diagnostic possibilities. This patient's differential diagnosis includes Bowen's disease (intraepidermal squamous cell carcinoma), psoriasis, tinea faciei, lichen planus, sarcoidosis, lupus vulgaris (cutaneous tuberculosis), and polymorphous light eruption.
Often the only way to sort through the differential diagnosis is to perform a full-thickness punch biopsy and to share the findings with the examining pathologist.

14. Dermatophytosis (tinea corporis) Nummular eczema
A 4-mm punch biopsy is taken, which proves to be diagnostic. What is the most likely diagnosis?
Pityriasis rosea
Psoriasis
Dermatophytosis (tinea corporis)
Nummular eczema
A 37-year-old businessman is referred to dermatology for the evaluation of round, scaly lesions that appeared suddenly three months previously, at around the same time his first child was born. The lesions, which are mostly asymptomatic, have been unresponsive to the application of over-the-counter antifungal creams (tolnaftate and clotrimazole). There are no pets in the house, and no one else in the household is similarly affected. Although he denies any history of skin problems, he believes his father had psoriasis. The patient does not smoke cigarettes, drink alcohol, or use prescription medications. He denies joint pain or swelling.
Examination reveals a total of five round, uniformly scaly lesions on truncal and extensor extremity skin (a right anterior tibial lesion is pictured). They average about 2.5 cm in diameter. There is a salmon pink erythema in the background, and the scale is notably white and tenaciously attached to the underlying skin. Microscopic examination of scrapings from the periphery of two of the lesions (using a KOH preparation) is negative for fungal elements.
Elsewhere on the patient's body, definite pits in four of 10 fingernail plates, scaly white plaques in the scalp, and scaling in both external auditory meatus are found. The patient's skin is not especially dry.
The correct answer is psoriasis (choice "b").
Pityriasis rosea lesions (choice "a") tend to be more numerous, oval rather than round, and unlikely to persist for three months. Also, the scale of pityriasis rosea lesions tends to concentrate in the middle of the lesions.
Clues that this is not tinea corporis (choice "c") are the negative KOH prep, the lack of response to topical antifungal treatment, the lack of any obvious source of fungal infection, and the uniform scaling (tinea corporis scaling tends to concentrate on the leading edge of the lesion). Nummular eczema (choice "d") is possible but unlikely without the requisite dry skin. Also, nummular eczema lesions tend to be orange-red.
As often happens in cases such as this, a biopsy was needed to sort through the differential diagnoses. However, with a positive family history of psoriasis, onset of stress, appropriate morphological appearance and distribution, and corroboratory findings of probable psoriasis on the scalp, nails, and ears, the diagnosis could have been made without it. Indeed, biopsies of any number of other conditions can show what are termed "psoriasiform features" and thus be quite misleading. That is why such pathology reports will often advise "careful clinical correlation." Another fairly reliable corroboratory area of involvement with psoriasis is the upper intergluteal skin, where there are often salmon pink patches that friction and moisture have prevented from becoming scaly.
Psoriasis is a common papulosquamous condition that affects about 2.6% of white persons. It is thought to be a manifestation of complex interaction between the patient's genetic makeup and environment. Factors known to exacerbate psoriasis include alcohol consumption, smoking, stress, bacterial antigen exposure, and use of certain medications, such as lithium.
Treatment in this case was relatively simple, with application of topical clobetasol ointment twice a day. The prognosis is good for control, but a cure is not likely given the current state of the art. We are, however, on the threshold of the introduction of completely new categories of medication that promise to be quite effective.

15. Epidermal nevus, congenital Seborrheic keratosis Wart
A 6-year-old boy is referred by his pediatrician to the dermatology department for evaluation and possible removal of a lesion. The lesion has been present since birth and has grown slowly with the child's growth. Initially thought to be a wart, it has persisted despite treatment with liquid nitrogen. The mother's main concern at this point is that her son's classmates are teasing him about the lesion. The child is otherwise healthy, and he is motivated to have the lesion removed.
Examination reveals a linear 6 1-cm epidermal collection of brown, relatively dry, warty papules. Examination of the rest of the patient's skin reveals no other remarkable findings.
Epidermal nevus, congenital
Seborrheic keratosis
Wart
Congenital compound nevus
The correct answer is "a," epidermal nevus (EN). EN represents inborn abnormalities of the epidermis, often involving the papillary dermis (a deeper layer of skin), which is why full-thickness excision is usually necessary for total ablation. Choice "b," seborrheic keratosis, does appear on children rarely, but not as a congenital lesion, and liquid nitrogen therapy would have been effective. Because of its warty surface, EN is often misdiagnosed as a wart but has nothing to do with the human papil- lomavirus; therefore "c," wart, is an incorrect answer. The congenital nature of the lesion would also argue strongly against that choice. If the lesion were choice "d," a congenital compound nevus, it would likely have been more intradermal in nature. Sometimes, however, only a biopsy can distinguish between an EN and a congenital compound nevus.
Although this patient's lesion is relatively trivial, EN can be extensive and disfiguring and can be associated with extracutaneous developmental abnormalities. These are described as part of a heterogeneous group of disorders called epidermal nevus syndrome. Other manifestations include Becker's nevus and nevus sebaceous. Therefore, in cases like this, it is important to examine the rest of the patient's skin.
Treatment and Prognosis
Often, the best option for epidermal nevus is to do nothing. In this case, however, after extensive discussion with the parents and the patient (including an explanation of the potential risks involved with excision, ie, scarring, pain, bleeding, infection, and wound dehiscence) the decision was made to excise the lesion under local anesthesia. This was carried out without complication, and no other treatment was necessary.

16. Malignant melanoma, acral-lentiginous type
A 56-year-old woman presents with a lesion on the lateral aspect of her right foot. She reports that she first noticed it five years ago and that it has been slowly growing in size. Then, a few months ago, the lesion began to focally ulcerate. The patient consulted her primary care provider, who diagnosed the lesion as cellulitis and prescribed cephalexin. The lesion failed to respond, however, so the patient was referred to the dermatology department.
The oddly pigmented, asymmetrical, 3-cm lesion is mostly macular, with focal areas of ulceration. It is not tender, red, or hot. The patient has red hair, fair skin, and blue eyes. She reports advanced sun damage from years of working as a lifeguard in Oklahoma.
An incisional biopsy is performed, incorporating the darkest, most irregular portion of the lesion. The results are diagnostic.
Malignant melanoma, acral-lentiginous type
Birthmark (congenital nevus)
Wart
Persistent cellulitis
The biopsy shows the lesion to be (a), a melanoma of 2.3-mm vertical thickness -- intermediate, according to Breslow staging (equivalent to Clark's level IV). This means that it has penetrated the reticular dermis and therefore is more likely to spread into the dermal vasculature -- the first step in the process of metastasis. The patient is immediately referred to undergo surgery for excision with margins and probable closure by full-thickness skin graft.

17. 0.75 mm (comparable to Clark Level II)
> mm (comparable to Clark Level III)
> mm (comparable to Clark Level IV)
> 4.0 mm (comparable to Clark Level V)
the overall five-year survival rate was 52 percent for patients with a primary melanoma of the foot or ankle compared to 84 percent for patients with melanoma on the thigh or calf.

18. A) Psoriatic nail disease B) Bacterial infection
A 40-year-old woman is seen in the dermatology clinic for evaluation of a "fungal infection" in her thumbnail. It has been present for six months -- despite an initial 10-day course of cephalexin and a two-month course of oral terbinafine, neither of which produced any change in the condition.
The patient is nondiabetic, not immunosuppressed, and otherwise healthy. Her toenails are not involved, nor are any other fingernails. She reports that she is prone to vaginal yeast infections which occur for no apparent reason several times a year. Personal and family history of psoriasis is negative.
Examination of the affected thumbnail reveals partial separation of the nail plate from the cuticle, a mildly dystrophic nail plate, modest edema, and scaling of the paronychial skin. Palpation of the latter is painful and produces a drop of pus, which is cultured. There are no rashes on her elbows or knees
A) Psoriatic nail disease
B) Bacterial infection
C) Squamous cell carcinoma
D) Chronic candidal paronychia
E) Onychomycosis (fungal infection)
It could have been psoriasis (a), but there are no corroboratory signs elsewhere and no personal or family history of that disease. Also, psoriatic nail disease is more likely to produce nail pits and less likely to result in separation of the nail plate from the cuticle (as seen in this case). It seldom causes pain in the affected nails.
Bacterial infection (b) of paronychial skin does not typically affect nails and is apt to be of an acute nature. It generally involves pus formation in a characteristic crescentic pattern and would have responded, at least partially, to cephalexin therapy.
Squamous cell carcinoma (c) occasionally develops in paronychial skin but would likely have demonstrated more of a focal effect (ulceration or nodule formation). Furthermore, squamous cell carcinoma is usually painless and seldom causes dystrophic nail changes.
Onychomycosis (e) rarely, if ever, produces paronychial tenderness or redness, nor does it typically involve separation of the nail plate from the cuticle. Furthermore, onychomycosis would likely have involved other nails and would have responded, at least partially, to terbinafine.
Chronic candidal paronychia is quite common and almost always misdiagnosed as fungal infection. It will not respond to terbinafine, as that agent has poor activity against Candida. After terbinafine fails, oral and/or topical antibiotics are usually tried and, of course, also fail.
If the patient is referred to a dermatologist, the condition is usually quickly recognized. Effective treatment involves oral ketoconazole 200 mg twice daily for two weeks, plus a topical imidazole (eg, oxicanazole cream) mixed half-and-half with triamcinolone cream applied to the affected area twice daily until the condition clears.
It is important to note that chronic candidal paronychia is not always easy to diagnose and treat. It is believed to be caused by chronic exposure to water and detergents. These encourage drying, which leads to separation of the nail plate from the cuticle, creating an entry point through which can come bacteria, yeast, and even foreign bodies (eg, food, dirt, and dead skin flakes); any of these can serve as a chronic irritant.
The most important point to be garnered from this case is that there is a differential for nail dystrophy that includes several non-fungal entities.

19. Bowen's disease (intraepidermal squamous cell carcinoma)
68-year-old woman presents with an "infection" in her right arm that has been unresponsive to oral and parenteral antibiotics (cephalexin, ciprofloxacin, and vancomycin). The problem started four weeks earlier, with a small rash that she treated with topical antibiotic cream. The outbreak rapidly worsened and the patient consulted her primary care provider, who placed her on the oral antibiotics and, when that failed, admitted her to the hospital.
The hospital's consulting infectious disease specialist obtains skin and blood cultures (neither showing any growth) and starts parenteral antibiotics, which yield no improvement. Since the patient's blood work results are unremarkable and she has no pain or fever, she is discharged and referred on an urgent basis to a dermatologist.
More history taking reveals that the patient and her family have been applying a number of topical agents to the arm throughout the course of the episode, including a hydroxyquinoline sulfate salve and triple antibiotic cream. Examination reveals an afebrile patient in no distress. The dorsum of her right arm is bright red, with an extensive papulovesicular rash covering the entire extensor surface in a sharply demarcated pattern. Neither epitrochlear nor axillary nodes are palpable. The arm itself is not tender, but there is significant edema present. The volar surface of the arm is unaffected.
Bacterial infection
Herpes zoster
Bowen's disease (intraepidermal squamous cell carcinoma)
Contact dermatitis

20. A 35-year-old man presents complaining of bumps on his upper back that have slowly grown slightly larger. The patient reports that although they are not painful, one in particular frequently gets irritated from contact with clothing. He believes that they have been present for years; there are no lesions elsewhere on his body. The patient's medical history is remarkable for hypertension, which is well controlled with ramipril. His family medical history is unremarkable.
The correct diagnosis is epidermal cysts. The most common form of cutaneous cyst, an epidermal cyst is a keratin-filled epidermal inclusion from within a hair follicle. Close inspection will reveal a keratin-plugged pore overlying the cyst, which is sometimes obvious (as in this case). Though commonly referred to as a sebaceous cyst, that designation is not histopathologically accurate as there is no sebaceous gland involvement.
Because of the fragility of the cyst wall, subcutaneous rupture is common; this can lead to an inflam- matory reaction that is often misdiagnosed as an infection. There are no other sequelae of consequence. Treatment is by simple excision, with care taken to remove the entire structure of the cyst without expelling the contents (if that is possible).

21. A 33-year-old man presents with an eruption of painful, itchy "blisters" on his hands and forearms evident for the past two days. There are no lesions elsewhere on his skin or mucous membranes. Contact history is negative, and the patient is taking no medications. He denies any previous eruptions.
The correct diagnosis is erythema multiforme (EM). The typical lesions of EM, as in this case, include variegate papules and vesicular lesions with a distinct erythematous margin. Many clinicians are accustomed to photos of more extensive involvement, seen in the major form of EM. This case, showing a limited distribution of the same characteristics, demonstrates the minor form of the condition. Biopsy of the lesion(s) may help to confirm the diagnosis. Although EM is associated with the use of several medications (eg, anticonvulsants and antibiotics) and infections (notably herpes simplex), it is often idiopathic. Treatment of minor cases involves removing or treating any offending etiology and administering symptomatic therapy, such as antihistamines. Cases of the major form may involve severe illness and require more aggressive and supportive therapy.

22. A 29-year-old man presents for evaluation of changes in and around a mole on his face. He states that the mole has been present for as long as he can remember but in recent months has begun to "lose some color". The patient is particularly concerned because the skin surrounding the mole has also lightened in color. He has several other moles that have not changed. The patient's medical history and family medical history are unremarkable, and he is taking no medications.
The correct diagnosis is halo nevus. Although the development of depigmentation around a preexisting melanocytic nevus may be alarming, this phenomenon is believed to represent immunologic changes related to spontaneous involution of the lesion; thus, the only required treatment is reassurance. The clinician must carefully evaluate all aspects of the nevus itself, however, to rule out melanoma within the nevus

23. During an examination an 18-year-old man on a visit for a nondermatologic condition, you note the presence of an ovoid, hypopigmented macule near his shoulder blade. Does it have any significance?
Although a final diagnosis cannot be made on the basis of the skin lesion, this is the classic ash leaf-shaped macule associated with tuberous sclerosis. While additional skin findings are possible in this disorder, it is not a dermatologic disease.
A complete explanation of tuberous sclerosis is beyond the scope of this column. However the case reinforces the principle that the skin serves as a window to the other organs systems. Thus, an astute clinician examines the skin not only for primary dermatological conditions, but for cutaneous manifestations of systemic disorders.
Figure 2. (click image to zoom)

24. A 14-year-old boy presents with a history of localized hair loss
A 14-year-old boy presents with a history of localized hair loss. His mother is not sure exactly how long this has been occurring: They may have noticed the patient's condition only because he is in the process of growing his hair to a longer style. She believes the area of hair loss may be slowly expanding.
The patient admits to mild pruritus but is more concerned about teasing from his football teammates. His medical history is unremarkable, and he is taking no medications.
The correct diagnosis is tinea capitis. Although most commonly a childhood disorder, this is occasionally seen in older patients, especially when environmental and vector factors are present -- in this case, shared football helmets. In this particular form of the disorder, there is little actual hair loss; rather, the hair shafts are easily broken off due to dermatophyte infection of the shaft itself. As is typical, little inflammation is seen here.
The diagnosis may be confirmed by several methods. Bright green fluorescence of the hair shaft under Wood's lamp examination is useful; however, the absence of fluorescence (as in this case) does not rule out the diagnosis. A positive KOH prep of the hair shaft -- not the skin -- would confirm the diagnosis, but the usefulness of this method depends on clinician experience. Fungal culture of the hair shafts is, of course, diagnostic as well.
Because the dermatophyte has invaded the bulb and the keratinaceous shaft, appropriate treatment involves oral, not topical, antifungal agents.

25. A 27-year-old man presents for treatment of "jock itch," which he states has been present for about six weeks. He has been using an over-the- counter powder marketed for this problem, without any result. He notes a prior history of athlete's foot, now resolved, and states that one of his teammates said the two conditions could be related. Past medical history is otherwise unremarkable. Physical examination reveals the lesions shown above but is otherwise unremarkable. There are no skin changes on the feet. KOH prep of the lesions above is positive; KOH prep of the interdigital spaces of the foot is negative
The correct diagnosis is candidiasis. Scrotal involvement and the presence of satellite lesions, above and beyond erythema and KOH-positive scale, are the hallmarks of clinical diagnosis. While this, like tinea cruris (jock itch), is a superficial fungal infection, the two are otherwise unrelated. Tinea cruris is a common manifestation, while cutaneous candidiasis in an adult should at least raise the question of altered immune status -- such as antibiotic use, diabetes, or human immunodeficiency virus seropositivity. Not all patients with candidiasis, however, will have these predisposing factors; frequent wetness with inadequate drying (often seen in athletes) can also provide a fertile ground for the causative organism. Appropriate treatment may include topical nystatin or oral imidazole antifungals, as well as adequate hygiene and drying. Any underlying factors should be addressed appropriately.

26. A 22-year-old man presents with an eruption on both forearms
A 22-year-old man presents with an eruption on both forearms. He says that the eruption has been present for a week and has not responded to over-the- counter hydrocortisone cream (0.5%). The eruption is intensely pruritic, and the patient scratches the affected area almost continuously during your interview. Past medical history reveals problems with chronic diarrhea (for which he is currently being worked up) and bipolar disorder. He is currently taking loperamide and lithium (his lithium level is within therapeutic range). The patient is employed by a lawn maintenance service
The correct diagnosis is dermatitis herpetiformis. Examination reveals profound excoriation and very few intact small vesicles, with a symmetric distribution on the extensor surfaces. The lesions lack the distinct linearity often seen in plant dermatitis, which was suggested by his occupation. Also, the apparent intensity of the pruritus is greater than expected in localized contact dermatitis, although this is somewhat subjective. This recurrent disorder has a high degree of association with small-bowel malabsorption—gluten-sensitive enteropathy—which turned out to be the cause of his chronic diarrhea. While the diagnosis of dermatitis herpetiformis should be suspected on the basis of this presentation, definitive diagnosis is achieved by biopsy and immunofluorescence staining of early lesions

27. A 65-year-old man presents for a routine physical examination
A 65-year-old man presents for a routine physical examination. There are several sharply demarcated, hyperpigmented macules on his shoulders, neck, and forearms. The patient reports increasing numbers of these macules in recent years but no symptoms associated with them. The lesions are nonscaling and have distinct margins and relatively uniform color, although some show intralesional pigment variation. The patient is currently taking atorvastatin calcium for hyperlipidemia; his medical history is otherwise unremarkable.
The diagnosis is solar lentigo, and the lesions are benign. They are caused by cumulative sun exposure and may coexist with other benign changes, such as the embedded seborrheic keratosis apparent in this particular lesion.Although there is no direct correlation, solar lentigo may also coexist with malignant changes, including low-grade melanomas such as lentigo maligna. Thus, it is important to scrutinize all lesions for changes suggestive of malignancy and, if warranted, to perform a biopsy.Generally, solar lentigo requires no treatment. If cosmesis is important, topical retinoids and cryotherapy can be used (with varying success).

28. A 24-year-old woman presents with a complaint of "fragile skin" on her hands. She states that for as long as she can remember, extremely minor trauma - such as bumping her hand on a counter top - causes the rapid formation of large blisters. There is no worsening with light exposure, but she does think the condition is more pronounced in the summer.
Medical history is unremarkable, as is the review of symptoms. The patient is taking no medications. Family medical history reveals that her father and one sibling have a similar, but less severe, condition. Physical examination reveals intact and collapsed semi-inflammatory vesicles and bullae to the hands. There are no mucosal lesions
The correct diagnosis is epidermolysis bullosa simplex (EBS), a somewhat uncommon mechanobullous disorder. A genetic disturbance with an autosomal dominant inheritance pattern, EBS has several subtypes, all of which produce a defect in epidermal protein production. This defect allows for the formation of vesicles and bullae following minor trauma, as in this patient's case.
While the generalized form is usually clinically present at birth, localized forms may not produce symptoms until early adulthood. Unlike the porphyrias, which EBS may resemble clinically, the condition is not related to light exposure. Biopsy is required to confirm the diagnosis.
Treatment is aimed at reducing trauma and preventing secondary bacterial infections, rather than at the underlying defect. Spontaneous improvement is not uncommon, however. As with all genetic disorders, patient education on inheritance patterns is appropriate.

29. A 33-year-old woman presents for a pruritic eruption on her lower left shin that has been present and worsening for two to three months. She is employed as a systems analyst. The patient is taking no medications. She has a negative contact history and an unremarkable medical history and review of systems. Examination reveals an eruption, confined to a single location, involving epidermal thickening and excoriation.
The correct diagnosis is lichen simplex chronicus. While there is likely some unknown abnormality of the skin that predisposes it to lichen simplex chronicus, the condition can be viewed simply as an exaggeration of the itch-scratch cycle. Something, usually mechanical, initiates pruritus, which in turn causes the patient to scratch, which leads to more itching, and so forth. As this cycle continues, inflammatory changes (eg, erythema) and epidermal defensive changes (eg, lichenification) occur. The eruption thus appears consistent with a more traditional rash with a more traditional etiology.
In the case of this patient, the mechanical irritant turned out to be a crosspiece in her workstation against which she rested her ankle. She also used the crosspiece to scratch the area. While the treatment -- completely breaking the itch-scratch cycle -- may seem simple, it can actually be quite difficult and may include multiple anti-inflammatory agents, mechanical protections, oral antipruritic agents, and even behavior modification. For this patient, changing her workstation to one without accessible crosspiece was of great benefit.

30. A 48-year-old woman presents for evaluation of "moles" on her eyelids
A 48-year-old woman presents for evaluation of "moles" on her eyelids. She states they have been present for several months and are slowly enlarging. She denies any associated symptoms such as pruritus, pain, or bleeding and has noted no other similar lesions. Past medical history is remarkable for hysterosalpingo-oophorectomy at age 45 years for fibroids, and she is currently receiving hormone replacement therapy. Family medical history is remarkable for coronary artery disease in her father and one brother.
The correct diagnosis is xanthelasma, or xanthomata of the eyelid. These slow-growing, yellowish, fatty plaques are the most common of the cutaneous xanthomas. In the majority of adult patients, they are not associated with lipid or lipoprotein disorders, although screening is warranted. Their presence in children, however, is strongly associated with these disorders.
Treatment of the lesions themselves, if desired, can be accomplished by excision or chemical ablation; recurrence is quite common, however

31. A 23-year-old man presents for a persistent, slowly worsening rash to the face. He states that it first occurred in January; it is now March. He denies any pruritus. He has experienced some relief with over-the- counter 0.5% topical hydrocortisone. The patient has tried changing soaps and shampoos without effect. He notes a fair amount of cosmetically unacceptable scale, including the scalp area, which he has been attempting to wash off. Past medical history and review of systems are unremarkable, and the patient is using no medications.
The correct diagnosis is seborrheic dermatitis. This very common disorder pre- dominantly affects the scalp and face, although there is generally more involvement of the forehead and eyebrows and less chin involvement than seen in this patient. Seborrheic dermatitis can also affect the upper chest and groin area. The typical eruption involves a greasy appearance (which patients may interpret as a hygiene issue) and scale, which may be yellow in appearance. With scalp involvement, dandruff is the result; in many patients, this is the complete manifestation of the disorder. Seborrheic dermatitis patients tend to have had their symptoms for some time before coming in; symptoms are likely to be more pronounced in late fall and winter.
Debate continues on the optimum treatment. While traditional topical steroids still have a role in therapy, topical ketoconazole (in cream or shampoo) is becoming the predominant treatment choice, due to the involvement of pityrosporum ovale in the pathogenesis of this disorder. Note, however, that other factors are also involved, and pityrosporum ovale has not been conclusively identified as the basic etiologic agent.

32. A 67-year-old man presents with a complaint of worsening "eczema
A 67-year-old man presents with a complaint of worsening "eczema." He states that he has a long history of eczema, with eruptions that worsen somewhat in the winter months. However, this current eruption on the trunk and extremities is more severe and pruitic than he has ever experienced. It has been present for about 10 days and has not responded to increased oral hydration, topical moisturizers, or topical corticosteroids. Past medical history is remarkable for episodic gout, for which he began allopurinol therapy last m
The correct diagnosis is drug eruption, exanthematous type. While the hyperkeratosis seen on the patient's wrist may suggest a chronic dermatitis such as that mentioned in his history, the widespread nature of the eruption and the "drug red" appearance are characteristic of this most common type of cutaneous drug eruption. Many drugs have been implicated in this diagnosis, and allopurinol is one that is known to cause a relatively high incidence of cutaneous reactions. Although practitioners typically think of these reactions as occuring soon after the initiation of a medication, they can occur in unsensitized patients three to four weeks after the drug is started. In fact, some medications that involve protein binding for antigenicity (eg, penicillin) can actually produce a reaction after a course of medication is complete. Management involves discontinuation of the causative agent and the use of oral antipruritics. Topical therapies are of no benefit.

33. A 40-year-old man presents for treatment of "athlete's foot
A 40-year-old man presents for treatment of "athlete's foot." He has a history of recurrences, which in the past have responded well to prescribed or over- the-counter topical antifungal agents. His current pruritic eruption has been gradually worsening for several weeks despite the use of topical clotrimazole. He has no other significant positive medical history. Examination reveals the eruption shown. The plantar surfaces and interdigital spaces are unremarkable, and KOH prep is negative.
The correct diagnosis is shoe dermatitis (contact dermatitis resulting from materials used in the construction of shoes). Although it would not be unusual for the KOH prep to be negative during treatment for tinea pedis, the pattern of eruption strongly suggests the diagnosis. The offending agent in shoe dermatitis is often in the uppers of the shoe, thus yielding the dorsal-only pattern of eruption seen here. Although tinea pedis can present with several patterns, complete sparing of the interdigital spaces and plantar surfaces would be somewhat unusual.
Appropriate management of this case should go beyond standard acute therapy. Because of the variety of offending agents - which can vary by shoe manufacturer - patients should be referred to a qualified dermatologist or allergist for patch testing. In this way, they can receive guidance not only on the specific agent(s) to which they are sensitive but also on how to select shoes to avoid them.