Moles and melanoma

Question 1

Benign melanocytic neoplasms 1

Answer 1

• Ephelides (freckles): small tan uniform pigmented macules, due to increase in melanin (normal # of melanocytes)
• Simple lentigo: small brown macule/papule w/ increased # of melanocytes and melanin
• Solar lentigo (liver spots): tan macules due to sun exposure (not precancerous)
• Seborrheic keratoses: benign pigmented epidermal tumor (keratinocytic proliferation), not a melanocytic neoplasm

Question 2

Benign melanocytic neoplasms 2

Answer 2

• Melanocytic nevi (mole): discolored macules or papules w/ symmetrical and well-circumscribed borders, due to proliferation of nevus (melanocyte-derived) cells
• Congenital nevi (birth marks): melanocytic proliferations present at birth, bigger ones have higher risk of developing melanoma
• Dysplastic nevus (atypical mole):

Question 3

Classification of acquired malanocytic nevi

Answer 3

• Junctional: proliferation of slightly altered melanocytes within epidermis only (not raised)
• Compound: migration to the dermis, within both (barely raised)
• Intradermal: loss of nevus cells in the epidermis, only in dermis (fully raised)

Question 4

Melanoma

Answer 4

• Abnormal proliferation of melanocytes (derived from neural crest cells), first grow horizontally (radially), then then vertically
• Melanocytes migrate from neural crest to: skin, eyes, inner ear, medulla oblongata (leptomeninges)
• Measure of tumor thickness (prognosis indicator): breslow’s depth (measure from stratum granulosum)
• 2mm breslow’s depth means 2 cm margins
• Dx requires histological confirmation
• In situ = only in epidermis

Question 5

Melanoma subtypes

Answer 5

• Superficial spreading: Arise on intermittently sun damaged skin (back of men, legs of women)
• Lentigo maligna: on chronically sun damaged skin (head and neck)
• Nodular: lacks radial growth phase, on sun-exposed and non-exposed areas (poor prognosis)
• Acral lentiginous: most common in people of color, arises usually on non-exposed areas

Question 6

Risk factors of melanoma

Answer 6

• Complexion (fitzpatrick type I- lightest skinned at highest risk)
• Response to sun exposure, amount of UV exposure
• Family or personal hx of melanoma (CDKN2A gene mutation: KOs p53 and RB, 50-70% have defected BRAF)
• Immunosuppresion,
• Melanocytic nevi/dystplastic nevi,
• Xeroderma pigmentosa
• Age, male gender

Question 7

Rx of melanomas

Answer 7

• Surgery, chemo, radiation, immunotherapy
• For surgery the # of mm deep (breslow’s depth) is the # of cm margins
• Sentinel lymph nodes should be biopsied
• Adjuvant therapy: increase IFN-a and IL2, ipilimumab (Abs against CTLA4, activating CD8s against melanoma), vemurafenib (targets BRAF mutation)
• Prevention: avoid sun, protective things (clothes, sunscreen)