1. Adult Cutaneous Fungal Infections
Medical Student Core Curriculum
in Dermatology
Last updated May 23, 2011

2. Module Instructions
The following module contains a number of blue, underlined terms which are hyperlinked to the dermatology glossary, an illustrated interactive guide to clinical dermatology and dermatopathology.
We encourage the learner to read all the hyperlinked information.

3. Goals and Objectives
The purpose of this module is to help medical students develop a clinical approach to the evaluation and initial management of patients presenting with cutaneous fungal infections.
By completing this module, the learner will be able to:
Identify and describe the morphologies of superficial fungal infections
Describe the correct procedure for performing a KOH examination and interpreting the results
Recognize the use and limitations of KOH examination and fungal cultures to diagnose fungal infections
Recommend an initial treatment plan for an adult with tinea pedis, tinea versicolor, candidal intertrigo, and seborrheic dermatitis

4. Superficial Fungal Infections: The Basics
Dermatophytoses are estimated to affect 20-25% of people worldwide, making them one of the most common infections.
Superficial cutaneous fungal infections are limited to the epidermis, as opposed to systemic fungal infections (e.g. endemic mycoses and opportunistic infections).
Three groups of cutaneous fungi cause superficial infections: dermatophytes, Malassezia spp., and Candida spp.
Dermatophytes (which include Trichophyton spp., Microsporum spp., and Epidermophyton spp.) infect keratinized tissues: the stratum corneum (outermost epidermal layer), the nail or the hair.
The term tinea is used for dermatophytoses and is modified according to the anatomic site of infection, e.g. tinea pedis

5. Case One
Mr. Eugene Brown

6. Case One: History
HPI: Eugene Brown is a 62-year-old healthy man who presents to his primary care physician with a one-year history of itching and burning of his feet.
PMH: no chronic illnesses or prior hospitalizations
Medications: none
Allergies: no known allergies
Family history: noncontributory
Social history: lives with wife, works as a banker
Health-related behaviors: reports no alcohol, tobacco or drug use
ROS: increased nocturia, otherwise negative

7. Case One: Skin Exam
How would you describe these exam findings?

8. Case One: Skin Exam
Erythema and scaling are present on the plantar surface and between the toes

9. Case One, Question 1
Which of the following is Mr. Brown’s most likely diagnosis?
Atopic dermatitis
Candidal intertrigo
Onychomycosis
Psoriasis
Tinea pedis 9

10. Case One, Question 1 Answer: e
Which of the following is Mr. Brown’s most likely diagnosis?
Atopic dermatitis (Characterized by red patches and plaques ± scale. Lichenification may also result)
Candida intertrigo (Erythematous, eroded areas with satellite papules. Less likely location)
Onychomycosis (Fungal infection of the nail)
Psoriasis (The interdigital and plantar surfaces of the toes are unusual locations for psoriasis. Would expect a well- demarcated plaque with a thick silvery scale)
Tinea Pedis

11. Tinea Pedis: The Basics
Tinea pedis (“athlete’s foot”) is the most common fungal infection seen in developed countries, and is most commonly caused by the fungus Trichophyton rubrum
Shoes provide an ideal environment for fungus to grow due to moisture
Public showers, gyms, and swimming pools are common sources of infection
It is difficult to permanently cure and may often recur
There are three clinical patterns of infection: interdigital, moccasin, and vesiculobullous type

12. Tinea Pedis: Interdigital Type
Most common, presents with scaling and redness between the toes and may have associated maceration.

13. Tinea Pedis: Moccasin Type
Also known as chronic hyperkeratotic type.
Sharply marginated scale, distributed along lateral borders of feet, heels, and soles.
At times, vesicles and erythema are present at the margins.
Often associated with onychomycosis (nail fungal infection).

14. Tinea Pedis: Moccasin Type
Moccasin type may present as “one hand, two feet” syndrome.
Affected hand shows unilateral fine scaling, particularly in the creases (see below), and nails are often involved.

15. Tinea Pedis: Vesiculobullous Type
Grouped, 2-3 mm vesicles or bullae are seen, often on the arch or instep. They may be itchy or painful.
Vesiculobullous type tinea pedis represents a delayed hypersensitivity immune response to a dermatophyte.

16. Back to Case One
Eugene Brown

17. Case One, Question 2
Which of the following is the most appropriate next step in diagnosis?
Begin empiric treatment with antifungals.
KOH exam
Skin biopsy
Wood’s light

18. Case One, Question 2 Answer: b
Which of the following is the most appropriate next step in diagnosis?
Begin empiric treatment with antifungals (First need a diagnosis. There are many scaly eruptions that can occur on the foot)
KOH exam
Skin biopsy (This is too invasive when a simpler test is available)
Wood’s light (Organisms will not fluoresce on wood’s light)

19. What are the diagnostic features in this KOH exam?
Case One: KOH Exam
What are the diagnostic features in this KOH exam?
Magnification 40x

20. What are the diagnostic features in this KOH exam?
Case One: KOH Exam
What are the diagnostic features in this KOH exam?
Parallel walls throughout the entire length
Septated and branching hyphae
Magnification 40x

21. KOH Exam: Basic Facts
KOH microscopy is the easiest and most cost effective method used to diagnose fungal infections of the hair, skin, and nail.
Proper technique requires training.
Sensitivity is dependent on the operator’s experience.
KOH dissolves keratinocytes to allow easy viewing of hyphae.
Heat is used to accelerate this reaction.

22. The KOH Exam Procedure Clean and moisten skin with alcohol swab
Collect scale with #15 scalpel blade
Put scale on center of glass slide
Add drop of KOH and coverslip; heat slide gently with flame to adequately dissolve keratin
Microscopy: scan at 10X to locate hyphae; then study in detail at 40X if needed
Click here to watch the video
Make sure to turn on your computer volume
(video length 8min 41sec)

23. Case One, Question 3
Which of the following are possible pitfalls of KOH prep?
False negative KOH due to prior partial treatment with antifungals
Misidentification of clothing fibers or lint as hyphae
Possibility of mistaking lipid or cell membranes for hyphae
All of the above are limitations

24. Case One, Question 3 Answer: d
Which of the following are possible pitfalls of KOH prep?
False negative KOH due to prior partial treatment with antifungals
Misidentification of clothing fibers or lint as hyphae (clothing fibers or lint are tapered, while hyphae have parallel walls throughout)
Possibility of mistaking lipid or cell membranes for hyphae (hyphae have parallel walls throughout and tend to be longer)
All of the above are limitations

25. Treatment of Tinea Pedis: Hygiene
For all types of tinea pedis, hygiene and topical antifungals are effective first-line therapies
Hygiene:
Dry the area after bathing
Change socks daily and alternate shoes worn
Consider wearing open shoes such as sandals
Use foot powder (available over the counter) to keep feet dry

26. Topical Antifungals
There are several classes of topical antifungal medications
Some classes are fungistatic (stop fungi from growing), others are fungicidal (they kill fungi)
Not all conditions are treatable with topical antifungals (specifically, hair infections and nail infections do not respond to topical treatment and require systemic treatment)

27. Treatment of Tinea Pedis: Topical
Topical antifungals: apply until tinea shows resolution, then continue treatment for a minimum of two weeks
Imidazoles: Fungistatic
Examples: clotrimazole, miconazole, sulconazole, oxiconazole, ketoconazole (least activity against dermatophytes)
Allylamines: Fungicidal
Examples: terbinafine, butenafine, naftifine
Ciclopirox: Fungicidal and fungistatic
Example: Ciclopirox olamine

28. Treatment of Tinea Pedis By Type
Interdigital:
Topical imidazoles, ciclopirox olamine, and allylamines
Plantar Moccasin/Chronic Hyperkeratotic:
Topical allylamines and imidazoles
Keratolytics are also useful: e.g. salicylic acid, benzoic acid (Whitfield’s ointment)*, urea, and lactic acid
Vesiculobullous:
Compresses in conjunction with antifungal agents
May require an oral agent such as terbinafine or itraconazole
* Whitfield’s ointment is a combination of salicylic and benzoic acid. In US can be bought through online pharmacies or compounded.

29. Case One, Question 5
Which of the following are common complications of tinea pedis? You may choose more than one answer.
Deep vein thrombosis
Furunculosis of the lower leg
Lower leg cellulitis
Peripheral neuropathy
Tinea corporis

30. Case One, Question 5 Answer: c & e
Which of the following are common complications of tinea pedis?
Deep vein thrombosis
Furunculosis of the lower leg
Lower leg cellulitis (the most common risk factor for lower leg cellulitis in immunocompetent non-diabetics is tinea pedis, which creates a portal of entry for bacteria)
Peripheral neuropathy
Tinea corporis (from autoinoculation) 30

31. Onychomycosis
Another complication of tinea pedis is onychomycosis, a chronic fungal infection of the nailbed that tends to spread to other nails.
Responds very poorly to topical antifungals
First line treatments are oral terbinafine or itraconazole

32. Onychomycosis
Identification of fungus in the affected nail (at minimum a positive KOH prep or nail biopsy) is necessary before treatment, for several reasons:
May mimic other conditions (e.g. psoriasis, lichen planus)
Treatment is expensive, of long duration, and with potential side effects
Oral antifungals also have drug-drug interactions

33. Case Two
Mr. Daniel Green

34. Case Two: History
HPI: Daniel Green is a healthy 18-year-old who presents with a lesion on his right leg that has been present for 2 weeks. The lesion is itchy and is growing in size.
PMH: no major illnesses or hospitalizations
Medications: none
Allergies: none
Family history: noncontributory
Social history: Lives with his parents and sister. The family adopted a puppy 3 months ago. No history of recent travel.
Health-related behaviors: no tobacco, alcohol or drug use.

35. Case Two: Skin Exam
How would you describe these exam findings?

36. Case Two: Skin Exam
This is a sharply marginated, erythematous annular lesion with central clearing and raised papulovesicular border with scaling.

37. Case Two, Question 1
Which of the following is the most appropriate next step in diagnosis?
Biopsy
KOH exam
Wood’s light exam
All of the above

38. Case Two, Question 1 Answer: b
Which of the following is the most appropriate next step in diagnosis?
Biopsy
KOH exam
Wood’s light exam
All of the above

39. Case Two, Question 2
Which of the following is the most likely diagnosis?
Atopic dermatitis
Psoriasis
Seborrheic dermatitis
Tinea corporis
Tinea cruris

40. Case Two, Question 2 Answer: d
Which of the following is the most likely diagnosis?
Atopic dermatitis (Poorly defined erythematous patches without central clearing)
Psoriasis (Well-demarcated erythematous plaques with silvery scale)
Seborrheic dermatitis (Inflammatory reaction to yeast typically affecting face, chest, and/or scalp, often with scaling)
Tinea corporis
Tinea cruris (Dermatophyte infection in the groin)

41. Tinea Corporis
Tinea corporis, “ringworm”, refers to dermatophytosis of the skin, usually affecting the trunk and limbs
Affects all age groups
Most prominent symptom is itching
Asymmetric distribution
The margin of the lesion is the most active; central area tends to heal
Scrapings should be taken from the red scaly margin for KOH exam
A variant of this is tinea cruris or “jock itch”, which has a similar presentation but appears in the groin

42. Tinea Corporis
Annular lesion with central clearing is typical of tinea corporis

43. Why Perform A Fungal Culture?
Cultures identify the specific species of fungi causing the infection
As opposed to tinea pedis, tinea corporis is caused by different fungal species with different environmental sources
Animals (cats/dogs), tinea capitis, tinea pedis
Using a fungal culture to identify the species will help identify the source and guide treatment
Even if the KOH prep is negative, a culture may be positive

44. Tinea Corporis: Treatment
Begin with topical treatment
Topical antifungals are applied until tinea shows resolution, then continue treatment for a minimum of two weeks
Imidazoles (fungistatic)
Allylamines (fungicidal)
Ciclopirox (fungicidal and fungistatic)
Oral antifungals are indicated in the following situations:
If there is a poor response to topical agents
If an animal is the source of infection
If eruptions involve a large surface area

45. Case Three
Ms. Anna Jones

46. Case Three: History
HPI: Ms. Jones is a 27-year-old woman who presents with mild itchiness of her back which began mid summer. She is also concerned about areas on her back that do not tan.
PMH: asthma
Medications: occasional multivitamin
Allergies: no known drug allergies
Social history: spends her summer months in Florida. Is an avid runner.
Health-related behaviors: occasional glass of wine 1-2 times per month, no tobacco or drug use
ROS: negative

47. Case Three: Skin Exam
How would you describe these exam findings?

48. Case Three: Skin Exam
Well-demarcated, pink and tan, macules and patches, across the back.

49. Case Three, Question 1
Which of the following is the most likely diagnosis?
Pityriasis alba
Seborrheic dermatitis
Tinea corporis
Tinea versicolor
Vitiligo

50. Case Three, Question 1 Answer: d
Which of the following is the most likely diagnosis?
Pityriasis alba (noninfectious, asymptomatic poorly- defined areas of hypopigmentation; self-limited)
Seborrheic dermatitis (abnormal immune response to normal skin yeast causing scaling and crusting)
Tinea corporis (fungal skin infection, presents as erythematous annular lesions with central clearing)
Tinea versicolor
Vitiligo (autoimmune loss/dysfunction of melanocytes causing areas of complete depigmentation)

51. Diagnosis: Tinea Versicolor
Tinea versicolor (aka Pityriasis versicolor) is not a dermatophytosis
It is an infection caused by species of Malassezia, a lipophilic yeast that is a normal resident in the keratin of the skin and hair follicles of individuals at puberty and beyond
Tends to recur annually in the summer months

52. Tinea Versicolor
Characterized by well-demarcated, tan, salmon, or hypopigmented patches, occurring most commonly on the trunk (facial involvement is rare)
Macules will grow, coalesce and various shapes and sizes are attained in an asymmetric distribution
Visible scale is not often present, but when rubbed with a finger or scalpel blade, scale is readily seen
This is a diagnostic feature of tinea versicolor
Evoked scale will disappear after treatment 52

53. A Closer Look at Tinea Versicolor

54. Case Three, Question 2
Which of the following is the most appropriate next step in management?
Fungal culture
KOH exam
Skin biopsy
Wood’s light exam

55. Case Three, Question 2 Answer: b
Which of the following is the most appropriate next step in management?
Fungal culture (Malassezia spp. are easily identified by a KOH exam but are not easily cultured)
KOH exam
Skin biopsy
Wood’s light exam

56. Microscopy
Spores (yeast forms)
Short
Hyphae
The KOH exam shows short hyphae and small round spores. Characteristic “spaghetti and meatball” pattern.

57. Microscopy with dye added to the specimen
Magnification 40x
Characteristic “spaghetti and meatball” pattern corresponding to hyphae and spores.

58. Tinea Versicolor: Morphology
It’s called “versicolor” because it can be light, dark, or pink to tan.
In untanned Caucasians, the lesions may be salmon-colored or brown.
In tanned Caucasians, the lesions may appear pale in comparison to the surrounding skin.
In darker skinned individuals, lesions may appear hyper- or hypopigmented.
Let’s look at some examples of the various colors of tinea versicolor.

59. Tinea Versicolor: lighter

60. Tinea Versicolor: darker

61. Tinea Versicolor: pink or tan

62. Case Three, Question 3
Which of the following treatments would you recommend for Ms. Jones?
Antifungal shampoo
Ketoconazole cream
Nystatin cream
Oral terbinafine

63. Case Three, Question 3 Answer: a
Which of the following treatments would you recommend for Ms. Jones?
Antifungal shampoo
Ketoconazole cream (effective for limited areas, but not widespread infections)
Nystatin cream (not effective)
Oral terbinafine (in contrast to topical terbinafine, oral terbinafine is not effective)

64. Case Three, Question 4
What is true about treatment of tinea versicolor?
Normal pigmentation should return within a week of treatment
Oral azoles should be used in most cases
When using shampoos as body wash, leave on for ten minutes before rinsing

65. Case Three, Question 4 Answer: c
What is true about treatment of tinea versicolor?
Normal pigmentation should return within a week of treatment (usually takes weeks to months to return to normal)
Oral azoles should be used in most cases (mild cases can be treated with topicals)
When using shampoos as body wash, leave on for ten minutes before rinsing

66. Tinea Versicolor: Topical Treatment
Shampoos: selenium sulfide 2% shampoo, ketoconazole shampoo, pyrithione zinc shampoo
Apply daily to affected areas, lather, and rinse
Spreads easily to cover larger areas
Azole creams: ketoconazole, econazole, miconazole, clotrimazole
Apply daily or bid for 2 weeks
Can be effective for limited areas, but infections tend to be widespread, so local topical treatment associated with high relapse rate
More expensive than shampoos

67. Tinea Versicolor: Oral treatment
Oral medication should be used when a large area is involved.
Oral medications of choice include:
Ketoconazole
Fluconazole
Itraconazole
Ketoconazole can be given as a one-time dose.
Take on an empty stomach, exercise until perspiring (medication is delivered via sweat), and avoid shower six hours after taking medication.

68. Tinea Versicolor: Maintenance Therapy
Many patients relapse
If the patient has had more than one previous episode then recommend maintenance therapy
Maintenance therapy: topicals are used 1-2x/week
Ketoconazole shampoo
Selenium sulfide (2.5%) lotion or shampoo
Salicylic acid/sulfur bar
Pyrithione zinc (bar or shampoo)
Refer patients who fail maintenance therapy to dermatology

69. Case Four
Ms. Betty Raskin

70. Case Four: History
HPI: Ms. Raskin is a 62-year-old woman who presents with a red itchy rash beneath her breasts
PMH: Type 2 diabetes (last hemoglobin A1c 9.2%), obesity
Medications: Metformin, which she says she often does not remember to take
Family history: noncontributory
Social history: lives in Texas part-time
Health-related behaviors: no tobacco, alcohol or drug use
ROS: negative

71. Case Four, Question 1
Which of the following best describe these characteristic exam findings?
Well-demarcated red plaques with overlying thick silvery scale
Grouped vesicles on an erythematous base
Sharply defined red plaques involving the skin folds with surrounding satellite papules
Inflammatory nodules

72. Case Four, Question 1 Answer: c
Which of the following best describe these characteristic exam findings?
Well-demarcated red plaques with overlying thick silvery scale
Grouped vesicles on an erythematous base
Sharply defined red plaques involving the skin folds with surrounding satellite papules
Inflammatory nodules 72

73. Case Four, Question 2
Which of the following is the most likely diagnosis?
Atopic dermatitis
Candidal intertrigo
Psoriasis
Seborrheic dermatitis
Tinea cruris

74. Case Four, Question 2 Answer: b
Which of the following is the most likely diagnosis?
Atopic dermatitis (chronic eruption of pruritic, erythematous, oozing papules and plaques, usually with secondary lichenification and excoriation)
Candidal intertrigo
Psoriasis (characterized by well-demarcated, erythematous papules and plaques with overlying silvery scale) 
Seborrheic dermatitis (typical skin findings range from fine white scale to erythematous patches and plaques with greasy, yellowish scale) 
Tinea cruris (dermatophytosis of the groin, genitalia, pubic area, perineal, and perianal skin, usually appears as multiple erythematous papulovesicles with a well-marginated, raised border)

75. Candidal Intertrigo: Basic Facts
Candidal intertrigo = candidiasis of large skin folds
May arise in the following areas:
Groin or armpits
Between the buttocks
Under large pendulous breasts
Under overhanging abdominal folds
KOH exam reveals pseudohyphae
Burns more than itches

76. Case Four, Question 3
Which of the following factors predispose to candidal intertrigo?
Diabetes mellitus
Hot, humid weather
Limited mobility
Obesity
All of the above

77. Case Four, Question 3 Answer: e
Which of the following factors predispose to candidal intertrigo?
Diabetes mellitus
Hot, humid weather
Limited mobility
Obesity
All of the above 77

78. Case Four, Question 4
Which of the following is the most appropriate next step in management?
Barrier creams or ointments (e.g. petroleum jelly, zinc oxide paste, etc.)
Nystatin ointment
Oral antifungal agent
Oral glucocorticoid

79. Case Four, Question 4 Answer: b
Which of the following is the most appropriate next step in management?
Barrier creams or ointments (useful as adjunct/preventive therapy, but does not eradicate candida)
Nystatin ointment (useful for candida, ointment base prevents maceration in moist areas)
Oral antifungal agent (usually can be treated with topical agent)
Oral glucocorticoid (may worsen the infection) 79

80. Candidal Intertrigo: Management
Topical antifungal agents
Polyenes and Imidazoles: nystatin, miconazole, clotrimazole, or econazole
Allylamines are not used to treat candida
Prevention
Keep intertriginous areas dry, clean, and cool
Encourage weight loss for obese patients
Washing with benzoyl peroxide bar may reduce Candida colonization

81. Candidal Intertrigo: Management
Topical anti-inflammatory
Low strength glucocorticoid preparations rapidly improves the itching and burning, but should be stopped after one week
Systemic antifungal agents (used for infections resistant to topical treatment)
Oral fluconazole, itraconazole, or ketoconazole

82. Take Home Points Cutaneous fungal infections are extremely common.
There are three clinical patterns of tinea pedis infection: interdigital, moccasin, and vesiculobullous type.
If it scales, scrape it! KOH examination is the easiest and most cost effective method used to diagnose fungal infections of the hair, skin, and nails.
Fungal culture is important because it may be positive when KOH prep is negative, and is the only easily available method to definitively identify the organism.
Culture is especially helpful in tinea corporis when the source of infection is not obvious (as opposed to tinea pedis).

83. Take Home Points
Tinea versicolor is characterized by well-demarcated, tan, salmon, or hypopigmented patches, occurring most commonly on the trunk.
Topical treatment is usually appropriate as a first-line agent for tinea pedis, tinea corporis, and candidal intertrigo, however oral medications are called for when involvement is extensive, when tinea corporis is thought to have been transmitted by an animal, and in fungal infections of the nails.
Fungal infections have high rates of recurrence after treatment, but maintaining a dry, clean skin environment is helpful for prevention.
Monitoring for recurrence and maintenance treatments may be helpful in patients with recurrent infection.

84. Acknowledgements
This module was developed by the American Academy of Dermatology Medical Student Core Curriculum Workgroup from
Primary authors: Iris Ahronowitz, MD; Ronda Farah, MD; Sarah D. Cipriano, MD, MPH; Raza Aly, PhD, MPH; Timothy G. Berger, MD, FAAD.
Peer reviewers: Heather Woodworth Wickless, MD, MPH; Daniel S. Loo, MD, FAAD.
Revisions and editing: Sarah D. Cipriano, MD, MPH; John Trinidad. Last revised July, 2011.

85. References
Aly R and Maibach H Atlas of Infections of the Skin. Churchill Livingstone.
Berger T, Hong J, Saeed S, Colaco S, Tsang M, Kasper R. The Web-Based Illustrated Clinical Dermatology Glossary. MedEdPORTAL; Available from:
De Kock CA, Sampers GH, Knottnerus JA. Diagnosis and management of cases of suspected dermatomycosis in The Netherlands: influence of general practice based potassium hydroxide testing. Br J Gen Pract Jul;45(396):
Erbagci Z. Topical therapy for dermatophytoses: should corticosteroids be included? Am J Clin Dermatol. 2004;5(6):

86. References
Gupta AK, Kogan N, Batra R. Pityriasis versicolor: a review of pharmacological treatment options. Expert Opin Pharmacother Feb;6(2):
Havlickova B, Czaika VA, Friedrich M. Epidemiological trends in skin mycoses worldwide. Mycoses Sep;51 Suppl 4:2-15.
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