Skin Cancer

Question 1

What are seborrheic keratoses? What do we see on histo? What is the explosive onset of many associated with?

Answer 1

• seborrheic keratoses are relatively common (especially in the elderly) benign squamous proliferations with increased basal pigmentation; usually of the trunk and face
• present as a raised discolored plaque with a classic “stuck on” appearance (appears as if you can peel them off)
• histo: circular whorls of pink keratin (pseudocysts)
• explosive onset: Leser-Trelat sign; indicates an underlying GIT carcinoma

Question 2

What is acanthosis nigricans? Where does it usually occur? What is it associated with?

Answer 2

• acanthosis nigricans is epidermal hyperplasia with darkening of the skin, resulting in dark “velvet-like” skin
• usually occurs in the groin and axilla
• associated with insulin resistance, T2DM, and malignancy (specifically, gastric carcinoma)

Question 3

What is basal cell carcinoma? What are the major risk factors? Where does it classically occur? What’s the prognosis?

Answer 3

• BCC is a malignant proliferation of epidermal basal cells (keratinocytes)
• it is the MOST common skin cancer
• presents as a shiny, pearl-like nodule with telangiectasia
• RFs: sunlight, albinism, xeroderma pigmentosum (an inherited enzyme defect, preventing nucleotide excision repair needed to repair UV damage)
• classically involves the UPPER lip
• excellent prognosis

Question 4

What is squamous cell carcinoma? What are the major risk factors? Where does it classically occur? What’s the prognosis?

Answer 4

• SCC is a malignant proliferation of epidermal squamous cells (keratinocytes)
• presents as an ulcerated nodular mass
• RFs: sunlight, albinism, xeroderma pigmentosum (an inherited enzyme defect, preventing nucleotide excision repair needed to repair UV damage); immunosuppression (SCC is the MOST common cancer associated with immunosuppression), arsenic poisoning, chronic inflammation
• classically involves the LOWER lip
• excellent prognosis

Question 5

What is the pre-malignant precursor to squamous cell carcinoma? What is Bowen’s disease?

Answer 5

• actinic/solar keratosis (intrapeithelial neoplasm of keratinocytes)
• they usually do NOT progress to invasive cancer (only 1% will do so)
• presents as a hyperkeratotic scaly plaque on the face, back, or neck
• Bowen’s disease is a highly differentiated in situ squamous cell carcinoma (5-10% will progress to invasive SCC)

Question 6

What is melanoma? What are the major risk factors? How does it grow?

Answer 6

• melanoma is a malignant proliferation of melanocytes
• it is the most common cause of death via skin cancer (but is 10x less common than nonmelanoma skin carcinoma)
• RFs: sunlight, albinism, xeroderma pigmentosum (an inherited enzyme defect, preventing nucleotide excision repair needed to repair UV damage), dysplastic nevus syndrome (genetic disorder with many dysplastic nevi)
• presents as a mole-like lesion with malignant ABCDE’s
• 2 stages of growth: initially, it undergoes radial growth (horizontal growth along the epidermis) and then it undergoes vertical growth (linear growth deep into the dermis)

Question 7

What are the four subtypes of melanoma? Which type of growth phase predominates in each? What’s the prognosis of each?

Answer 7

• 1) lentigo maligna melanoma: lentiginous proliferation (radial growth) only (rarely become invasive); good prognosis (precursor lesion is Hutchinson’s melanotic freckle; sun-damaged faces of elderly)
• 2) superficial spreading melanoma: MOST COMMON type; radial growth phase dominates; good prognosis
• 3) nodular melanoma: early vertical growth phase; poor prognosis
• 4) acral lentiginous melanoma: most common in dark skinned patients; involves the palms, soles, and nails; is NOT associated with UV radiation