Block 2 PATH Exam -- Melanocytic Tumors Lecture
Terms
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- Lentigo
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Flat, brown spots that show increased #s of melanocytes
Melanocytes are enlarged --> increased amounts of melanin - Peutz-Jeghers Syndrome
- Multiple lentigines in a perioral distribution and on hands and feet
- Ephelis
- Freckle
- Cafe Au Lait Macules
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Freckles, but larger
6 such spots (each > 1.5 cm) is highly suggestive of neurofibromatosis - Nevi
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Moles
Junctional -- dermal-epidermal junction
Compound -- junction as well as the dermis
Intradermal -- limited to the dermis
Any alteration should be an indication for removal - Spindle and Epithelioid Cell Nevus
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Nests of large spindle and epithelioid melanocytes
Most occur in children (25% in adults) - Blue Nevus
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Slightly elevated, blue or black lesion
Commonly seen on buttock, dorsa of hands/feet, and face
Pigmented, DENDRITIC melanocytes in the dermis - Congenital Nevus
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Rarely present at birth
Large ones are a risk for evolving into malignant melanoma - Malignant Melanoma
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Rarely, is primary in a visceral site
(Ex. gall bladder, eye, meninges)
Median age at Dx is late 50s
Skin pigmentation confers protection
Incidence similar in males and females
Etiology unknown
Linear rise in incidence with DECREASING LATITUDE
Episodic severe sun exposure more important than chronic, moderate
Women have better prognosis than men
Extremities have more favorable prognosis than other sites - Superficial Spreading Malignant Melanoma
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~70% of all
Legs in females, Back in men
Long radial growth phase - Lentigo Maliga Melanoma
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Affects sun-exposed skin
Later middle aged - elderly individuals
Radial growth phase of 10 - 40 yrs before vertical growth - Nodular Malignant Melanoma
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~10 - 15% of all
Radial growth phase is so short that it is missed
Lesion seems to evolve as a nodule from the start - Acral Lentiginous Melanoma
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The least common type
BUT, most common in blacks, Asians, Amer. Inds., Hisp.
Lesions on palms, soles, sublingually, or in mucous membranes - Clark System
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Level I -- In Situ
Level II -- Invades papillary dermis
Level III -- fills papillary dermis
Level IV -- invades the reticular dermis
Level V -- invades the subcutaneous fat - Breslow thickness
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Single most useful histopathologic indicator of prognosis
<0.75 mm almost never metastasize
>4 mm metastasize in > 60% of cases