Dermatology pathology 2 - skin infections and cancer

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Dermatology pathology 2 - skin infections and cancer
2013-04-02 13:29:05

Derm path: skin infections, cancer
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  1. Impetigo
    • Very superficial skin infection
    • S. aureus, S. pyogenes
    • Highly contagious
    • Honey-colored crusting
    • Bullous impetigo has bullae and is usually S. aureus

  2. Cellulitis
    • Acute, painful, spreading infection of dermis and subcutaneous tissue
    • S. pyogenes, S. aureus
    • Often starts with break in skin from trauma, or from another infection

  3. Necrotizing fasciitis
    • Deeper tissue injury
    • anaerobic bacteria, S. pyogenes
    • Crepitus from methane and CO2 production
    • "Flesh-eating bacteria"
    • Causes bullae and purple color to skin
  4. Staphylococcal scalded skin syndrome (SSSS)
    • Exotoxin destroys keratinocyte attachments in the stratum granulosum only
    • (vs. toxic epidermal necrosis → destroys epidermal-dermal junction)
    • Fever, generalized erythematous rash
    • sloughing of upper layer of epidermis
    • heals completely
    • seen in newborns, children

  5. Hairy leukoplakia
    • White, painless plaques on tongue
    • CANNOT be scraped off
    • EBV mediated
    • Occurs in HIV-positive patients

  6. Basal cell carcinoma
    • Most common skin cancer
    • Sun-exposed areas of the body
    • Locally invasive, rarely metastatic
    • Pink, pearly nodules, commonly with telangiectasias, rolled borders, central crusting or ulceration (A)
    • BCC can appear as nonhealing ulcer with infiltrating growth (B)
    • Scaling plaque (superficial BCC) (C)
    • Basal cell tumors have "palisading" nuclei (D)

  7. Squamous cell carcinoma
    • Second most common skin cancer
    • Associations: excessive exposure to sunlight, immunosuppression, arsenic exposure; chronic draining sinuses
    • Location: commonly appears on face (E), lower lip (F), ears, hands
    • Locally invasive, may spread to LN, rarely metastasize
    • Ulcerative red lesions with frequent scale
    • Histology: keratin "pearls" (G)
    • Actinic keratosisa scaly plaque; precursor to SCC
    • Keratoacanthoma: variant that grows rapidly (4-6 weeks) may regress spontaneously over months (H)

  8. Melanoma
    • Common tumor with significant metastasis risk; depth of tumor correlates with risk of mets
    • Tumor marker: S-100
    • Associations: sun exposure, fair-skined persons
    • Many types: superficial, nodular, lentigo maligna, acrolentiginous
    • ABCDs: Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolution over time
    • Activating mutation in BRAF kinase
    • Tx: excision with wide margins; Vemurafenib (BRAF kinase inhibitor) in pts with unresectable melanoma with BRAF V600E mutation