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36 Cards in this Set
- Front
- Back
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Where do melanocytes originate from? Where do they live?
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The neural crest. They migrate to the epidermis and the dermis, retina, inner ear, leptomeninges (pia mater, arachnoid mater), located usually in the basal layer
They transfer pigment to the keratinocytes |
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What are the three main histological types of warts?
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1. Junctional
2. Compound 3. Intradermal |
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Junctional nevi: characteristics
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- Smooth macules
- Commonly dark brown - Melanocytic nests present at dermo-epidermal junction |
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Compound nevi: characteristics
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- Raised lesions
- Light to medium brown - Nests of melanocytes at the junction AND in the dermis |
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Intradermal nevi: characteristics
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- Raised
- Flesh-colored to tan - Nests of melanocytes ONLY IN THE DERMIS - Nests become smaller deeper into the dermis |
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What causes nevi to be raised?
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Deeper growth
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Congenital melanocytic nevi: characteristics
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- Present at birth
- Extend more deeply than common nevi - Risk of melanoma inc 2-15% with giant (> 2 cm) nevi. - Lesions that cross the midline impart an increased risk of CNS involvement. - Growth around hair follicles and blood vessels. |
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Blue nevi: characteristics
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- Well-circumscribed, round
- Blue-black in color because of the Tyndall effect (dermis reflects light) - Most often on dorsal hands, feet, face, scalp |
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Dysplastic nevi: incr risk of what?
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melanoma
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Who is at greatest risk for developing melanoma?
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White men
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Melanoma: basic epi stats
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Least common of all skin cancers (4%), but is the most deadly (79% of deaths)
#1 cause of cancer-related death in women aged 25-30 |
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What type of sunlight exposure predisposes for melanoma? For basal cell carcinoma?
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Melanoma: Intense intermittent exposure, especially as a child.
BCC: chronic, cumulative exposure |
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FAMM
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Familial atypical mole-melanoma syndrome
- 150-fold increased risk of developing MM - 500-fold risk of MM if previous hx of MM - Lifetime risk approaches 100% by age 70 |
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Melanoma: pathogenesis/genetics
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- Tumor suppressor genes turned off (Rb, p53)
- Proto-oncogenes - CDKN2A: p16 and p14 inactivate Rb and p53 respectively (this is the mutation in familial melanoma) |
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What are the subtypes of melanoma? (5)
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- Superficial spreading
- Nodular - Lentigo maligna - Acral lentiginous - Amelanotic |
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Superficial spreading melanoma: characteristics
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- Most common type (60-70% of melanomas)
- Median age = 50 - Upper back in men/women, legs in women - May arise de-novo or within a nevus - Has a radial growth phase (horizontal), and a later vertical growth phase (more worrisome) with appearance of nodule - May show areas of regression as scalloped margins/varied pigment |
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What causes regression of melanomas?
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Melanoma are very immunogenic --> the immune system tries to fight off --> regression
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Nodular melanoma: characteristics
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- About 15-20% of melanomas
- 2x more common in men - Sun-exposed areas - Primarily vertical growth - They BLEED later in course |
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Acral lentiginous melanoma: characteristics
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- 5-10% of melanomas
- Median 50 y.o., M=F - #1 type in darker skinned/Asian patients - In blacks: foot is the #1 site (50% are subungual or plantar) - Mets common due to delayed diagnosis |
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Longitudinal melanonychia
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Melanoma presenting as a pigmented stripe on the nail.
Can be common in darker skinned people? But worrisome if it is one nail in a white person |
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Lentigo maligna/Lentigo maligna melanoma: characteristics
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Atypical melanocytes extending over at least 3 rete ridges in chronically sun-damaged skin.
- IN SITU - Head most common site - Indolent growth with radial phase that can last 5-20 years - Proliferation is at the DEJunction and may be ONE CELL thick, so lesion is often larger than it appears. Lentigo maligna melanoma: invasive version |
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Amelanocytic melanoma: characteristics
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- Mimics BCC, pyogenic granulomas
- See in pts with albinism - Only differs in lack of pigment |
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What are some factors in diagnosing nevi?
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ABCDE:
- Asymmetry - Borders - Color - Diameter - Evolution (history of change, bleeding, itching) - "Ugly duckling" sign: focus on the nevus that is the ugliest |
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What are the stages of melanoma?
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Stage 1: < 1 mm
Stage 2: > 1 mm Stage 3: LN involvement |
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Melanoma: indications for when you need to do more tests than just a biopsy
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- When LN are enlarged to touch --> LN dissection
- Tumor is thicker than 1 mm --> may do a sentinel lymph node biopsy - More advanced tumor stage or patient has specific symptoms --> do a CT scan or a PET scan |
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What is the most important prognostic factor for melanoma?
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LN involvement
Do sentinel LN biopsy if > 1 mm Note that sentinel LN biopsy does not provide a survival benefit |
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Melanoma: prognostic factors
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- Male sex
- Thickness (Breslow) - UIceration (likely to be deep) - Regression (scar tissue pushes melanocytes deeper) - Mitoses, etc - Lymphocytic infiltrate confers a BETTER prognosis |
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Melanoma: what are the guidelines for follow-up?
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- H&P every 3 months year for 2 years then 1-2x per year after
- remember that there is a 5-10% risk of developing a second melanoma |
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What are the types of benign melanocytic nevi? (5)
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1. Congenital nevus
2. Blue nevus 3. Spitz nevus 4. Halo nevus 5. Dysplastic nevus |
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Congenital melanocytic nevus: histo
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- Extensive but symmetric
- Deep lobular growth around adnexal structures and BLOOD VESSELS. - No cytological atypia or mitoses |
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Blue nevi: histo
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- Spindle shaped (whorls) melanocytes in the dermis
- Perivascular growth - Dermal fibrosis - No cytological atypia - CAN BE CONFUSED WITH TATTOOS - Stain with S-100 |
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What is pagetoid spread?
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Upward migration of atypical melanocytes until there are melanocytes in all layers of the epidermis
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Malignant melanoma: histo
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- Lateral spreading of irregular nests
- Pagetoid spread |
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What are the common variants of malignant melanoma? (histo, 6)
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1. Superficial spreading melanoma
2. Melanoma in SITU 3. Lentigo maligna 4. Nodular melanoma 5. Desmoplastic melanoma 6. Metastatic melanoma |
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Lentigo maligna: txt
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Topicals
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Desmoplastic melanoma: histo
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- Often not pigmented
- Minimal epidermal involvement - Spindle shaped melanocytes - Deep, penetrating growth - *Lymphoid aggregates* - Very hard to detect |
