Ch. 6 - Melanocytic neoplasms Flashcards
Solar lentigo
(differential?)
Thin rete with bulbous melanotic tips.
Consider reticulated seborrheic keratosis
Melanotic macule
Broad and squared-off rete with pigment at the basal layer. No nevus component.
Benign melanocytic nevus
Sharply defined, well-nested melanocyte lesion without deep mitoses and with dispersion at the deep dermal aspect.
How can maturation be assessed in a melanocytic nevus?
HMB-45 immunostaining (top-heavy, loses staining in the deep component)
What is the utility of MIB-1 in diagnosing melanocytic nevi?
it is an immunostaining marker found in all phases of the cell cycle (except G0) which should not stain deep melanocytic nuclei.
Balloon cell nevus
Sharply defined, well-nested lesion with balloon cells and without atypia.
*Balloon chnage is a degenerative feature characterized by swelling of cellular organelles
“Neural” nevus
Well-defined nevus with S-shaped spindle cells (similar to neurofibroma) and nevic corpuscles resembling Meissner corpuscles.
Congenital nevus
Broad, cytologically bland nevus often associated with follicles, vessel walls, and nerves. Patchy perivascular or single-file interstitial pattern.
Spitz nevus
Somewhat atypical-looking nevus with vertically oriented nests surrounded by clefts, pink Kamino bodies, and large spindle and epithelioid cells.
What are the molecular features of Spitz nevi?
Most have a normal chromosome complement. Some large Spitz nevi have an 11p gain.
Pigmented spindle cell nevus of Reed
Clefted, vertically oriented nevus (Spitzoid), but with a greater spindle component (less epithelioid) and smaller melanocytes.
Acral nevus
Sharply nested nevus with normal maturation and some central buckshot scatter. If volar, nests can be elongated.
“Ancient” nevus
Sharply defined, benign-appearing nevus with large, hyperchromatic atypia. No mitoses!
Halo nevus
Sharply-nested nevus with band-like lymphoid infiltrate (intermingling melanocytes and lymphocytes, unlike in melanoma).
Blue nevus
Wedged or bulbous nevus with pigment to the base and a distinctive sclerotic stroma.
What are the key features of:
Cellular blue nevi?
Epithelioid blue nevi?
Deep penetrating nevi?
Cellular: Fusiform melanocytes with vesicular nuclei and prominent nucleoli.
Epithelioid: Associated with Carney complex. No sclerotic stroma.
Deep penetrating: Small hyperchromatic nuclei and smudged chromatin
Dysplastic nevus
Large, oval lesion with irregular pigment, fading macular “shoulder” border, club-shaped rete hyperplasia.
How are dysplastic nevi graded?
Low-grade: Atypia restricted to shoulder region
Moderate: Atypia in both shoulder and central regions.
High-grade: High-grade atypia, irregular nests.
Junctional lentiginous nevus
Dysplastic-appearing nevus with club-shaped epidermal hyperplasia with restriction of nests to the tips and sides of rete.
Recurrent nevus (pseudomelanoma)
Confluent, poorly nested junctional melanocytic porliferation above prior resection scar. Rule out melanoma!
Nevus of Ota/Ito
Band of dendritic melanocytes in the upper dermis without sclerotic stroma.
Ota = face Ito = shoulder
Mongolian spot
Dendritic melanocytes scattered between collagen bundles in the lower half of the dermis (vs Nevus of Ito/Ota) without sclerotic stroma.
What are the two phases of melanoma growth?
Lentiginous growth (in situ component) confined within the DEJ.
Vetical growth with invasion of reticular dermis and mitoses or necrosis.
How is Breslow depth measured?
From the granular layer, base of an ulcer, or inner root sheath (if adnexal).
