1. Dr. Bennett Fontenot MD, PhD, JD, RN, RD, DMD, DDS, NP, BS, esq, PA
Skin and SubQ
Basic Science
4/6/10
Dr. Bennett Fontenot MD, PhD, JD, RN, RD, DMD, DDS, NP, BS, esq, PA

2. Anatomy Epidermis Keratinocytes Melanocytes Langerhans' cells
stratum germinatum (basal), spinosum, granulosum, lucidum, corneum.
Lose mitotic ability – days
Melanocytes
derived from precursor cells of the neural crest
extend dendritic processes upward from basal cell
pigment is packaged into melanosomes and transported into the epidermis via dendritic processes, phagocytized by keritinocyes
Despite differences in skin tone, the density of melanocytes is constant among individuals.
Rate of melanin production, transfer to keratinocytes, and melanosome degradation that determine the degree of skin pigmentation.
Langerhans' cells
act as the skin's macrophages.
Express class II MHC antigens, and has antigen-presenting capabilities

3. Anatomy
Dermis
Collagen- constitutes 70% of dermal dry weight and is responsible for its tensile strength.
the skin primarily contains type I collagen
Fetal dermis and new wounds contains mostly type III (reticulin fibers) collagen
Elastic fibers
Glycosaminoglycans complexes
Cutaneous sensation
Meissner's, Ruffini's, and Pacini's corpuscles transmit information on local pressure, vibration, and touch

4. Anatomy Three main adnexal structures:
eccrine glands- sweat-producing eccrine glands are located over the entire body
pilosebaceous units
Hair folicles and sebaceous glands
reservoir of pluripotential stem cells critical in epidermal reproductivity
In skin graft harvest, residual hair follicles supply new keratinocytes to regenerate the epidermis and restore skin integrity
apocrine glands
primarily found in the axillae and anogenital region
predispose both regions to suppurative hydroadenitis

5. Injuries Traumatic Caustic
Dog Bites- Pasteurella multocida – Augmentin
Human Bites- Eikenella corrodens
Dirty- allow to heal by secondary intention after debridement and irrigation
Caustic
Acid:
coagulative injury
copious skin irrigation for at least 30 minutes with water
hydrofluoric acid - neutralized with calcium,
Alkaline agents
liquefactive injury - a longer, more sustained period of injury
iirrigation of the affected area with continuous water flow should be maintained for at least 2 hours

6. Infections/Inflammatory Diseases

7. Folliculitis, Furuncles, and Carbuncles
Folliculitis is an infection of the hair follicle.
Usually Staphylococcus, but gram-negative organisms may cause follicular inflammation as well.
Furuncle (boil) begins as folliculitis, but may eventually progress to form a fluctuant abscess
Carbuncle- more involved, deep-seated infections that result in multiple draining cutaneous sinuses are called carbuncles.
Furuncle/Carbuncle require I&D +/- ABX

8. Infections/Inflammatory Diseases

9. Necrotizing fasciitis
The most common sites are the external genitalia, perineum, or abdominal wall (Fournier gangrene).
Necrotizing fasciitis represents a rapid, extensive infection of the fascia deep to the adipose tissue, without involvement of muscle.
Necrotizing myositis primarily involves the muscles but typically spreads to adjacent soft tissues.
The most common organisms
Group A streptococci, Clostridium species
Gram-negative species- Escherichia coli, Enterobacter, Pseudomonas species,
Clinical risk factors - diabetes mellitus, malnutrition, obesity, steroid use, renal failure, cirrhosis.
Management - broad-spectrum IV antibiotics, aggressive surgical debridement.

10. Infections/Inflammatory Diseases

11. Hidradenitis Suppurativa
Defect of the terminal follicular epithelium.
Apocrine gland blockage, obstructed infection leads to abscess formation throughout affected axillary, inguinal, and perianal regions.
Foul-smelling sinuses
Treatment
Acute infections- application of warm compresses, antibiotics, and open drainage.
Chronic hidradenitis- wide excision is required and closure may be achieved via skin graft or local flap placement

12. Benign Tumors
Cysts
Epidermal cysts- most common type, may present as a single, firm nodule anywhere on the body.
Dermoid cysts- are congenital lesions that result when epithelium is trapped during fetal midline
Trichilemmal (pilar) cysts- most often on the scalp of females. When ruptured, these cysts have an intense, characteristic odor.
Difficult to distinguish one type of cyst from another: Each cyst presents as a subcutaneous, thin-walled nodule containing keratin
If infected- tx with I&D, must remove all of cyst wall to prevent recurrence
Acrochordons, Dermatofibromas, Lipomas

13. MALIGNANT TUMORS Basal Cell Carcinoma
the most common type of skin cancer
Waxy and cream colored, present with rolled, pearly borders surrounding a central ulcer.
Slow growing, and metastasis is extremely rare
Extensive local tissue destruction is common
Treament:
Surgical excision with 0.5-cm to 1-cm margins.
Tumors located on the cheek, nose, or lip, may be best approached with Mohs' surgery

14. MALIGNANT TUMORS Squamous Cell Carcinoma
Arise from epidermal keratinocytes
increased invasiveness and tendency to metastasize.
Before local invasion, in situ SCC lesions are termed Bowen's disease.
In situ SCC tumors specific to the penis are referred to as erythroplasia of Queyrat
Lesions arising in burn scars (Marjolin's ulcer), areas of chronic osteomyelitis, and areas of previous injury metastasize early
Treament:
Surgical excision with 1-cm margins.
Tumors located on the cheek, nose, or lip, may be approached with Mohs' surgery
The need for lymph node (LN) dissection remains a topic of debate.
Regional LN excision is indicated for clinically palpable nodes
lesions arising in chronic wounds are more aggressive- prophylactic LN dissection is indicated.
Metastatic disease is a poor prognostic sign, and only 13% of patients typically survive 10 years.

15. APC Gene and Familial Adenomatous Polyposis
Hundreds to thousands of polyps in the colon and rectum. The polyps usually appear in adolescence and, if left untreated, progress to colorectal cancer.
FAP is associated with benign extracolonic manifestations
congenital hypertrophy
retinal pigment epithelium
epidermoid cysts, and osteomas.
Also at risk for
upper intestinal neoplasms (gastric and duodenal polyps, duodenal and periampullary cancer),
hepatobiliary tumors (hepatoblastoma, pancreatic cancer, and cholangiocarcinoma),
thyroid carcinomas, desmoid tumors, and medulloblastomas.
Gardner’s and Turcot’s

16. Mismatch Repair Genes and Hereditary Nonpolyposis Colorectal Cancer (HNPCC)
Autosomal dominant hereditary cancer syndrome that predisposes to a wide spectrum of cancers, including colorectal cancer without polyposis.
HNPCC consists of at least two syndromes:
Lynch syndrome 1- colorectal cancer with early age
Lynch syndrome 2- colorectal cancer + carcinoma of the endometrium, transitional cell carcinoma of the ureter and renal pelvis, and carcinomas of the stomach, small bowel, ovary, and pancreas.
Amsterdam Criteria

17. The Melanoma Superficial spreading, Nodular type Lentigo maligna
Most common- accounts for up to 70% of melanomas.
typically flat and measure 1 to 2 cm in diameter at diagnosis.
Before vertical extension, a prolonged radial growth phase is characteristic
Nodular type
accounts for 15 to 30% of melanomas.
lack of radial growth; all are in the vertical growth phase at diagnosis.
Lentigo maligna
accounts for 4 to 15% of melanomas,
most frequently on the neck, face, and hands of the
best prognosis because invasive growth occurs late.
Acral lentiginous
least common subtype, and constitutes only 2 to 8%
29 to 72% of all melanomas in dark-skinned people
on the palms, soles, and subungual regions.

18. Prognosis Prognosis is based on Depth of Invasion
Presence of ulceration confers a worse prognosis for same depth of invasion
Nodular melanomas have the same prognosis as superficial spreading types when lesions are matched for depth of invasion.
Lentigo maligna has a better prognosis even after correcting for thickness, and acral lentiginous has a worse prognosis

19. Breslow Thickness

20. Diagnosis
Requires excisional biopsy or incisional Bx

21. Nodes

22. Nodes
All microscopically or clinically positive LNs should be removed by regional nodal dissection.
When groin LNs are removed, the deep (iliac) nodes must be removed along with the superficial (inguinal) nodes,
For axillary dissections, the nodes medial to the pectoralis minor muscle also must be resected.
For lesions on the face, anterior scalp, and ear, a superficial parotidectomy to remove parotid nodes and a modified neck dissection is recommended.

23. Mets
Once melanoma has spread to a distant site, median survival is 7 to 8 months
5-year survival rate is less than 5%.
Solitary lesions in the brain, GI tract, or skin that are symptomatic should be excised when possible.
Use of radiation therapy, regional and systemic chemotherapy, and immunotherapy are all under investigation – interferon alpha