Palmoplantar warts show especially prominent keratohyaline inclusions • Lesions may be irritated and inflamed, often associated with reactive atypia Top Differential Diagnoses • Verrucous keratosis • Seborrheic keratosis • Lichen simplex chronicus • Hypertrophic lichen…
Medium-sized epithelioid cells, large epithelioid cells, and spindled cells • Spindled blue nevus-like cells • Large epithelioid cells • Does not exhibit brisk dermal mitotic activity Ancillary Tests • Loss of expression for protein…
Eccrine angiomatous hamartoma – Sweating angiomatous hamartoma – Functioning sudoriparous angiomatous hamartoma – Sudoriparous angioma Porokeratotic eccrine ostial and dermal duct nevus – Porokeratotic eccrine duct and hair follicle nevus – Porokeratotic adnexal ostial nevus…
Mucinous breast carcinoma Mucinous colonic carcinoma • Other primary cutaneous tumors with mucin Basal cell carcinoma Adenoid cystic carcinoma Low Magnification of Primary Cutaneous Mucinous CarcinomaLow-power view of primary cutaneous mucinous…
May be more common on head and neck Microscopic • Lesion overall orderly, symmetric, and well circumscribed • Most commonly: Compound/intradermal melanocytic nevus plus blue nevus • Others types of combined nevi include…
Peritheliomatous: Distinctive and unique for sinonasal melanoma • Variety of cell types can be seen Undifferentiated, epithelioid, polygonal, small cell, plasmacytoid, rhabdoid, giant cell • Prominent, irregular, brightly eosinophilic, enlarged nucleoli • Intranuclear…
Ovoid, clear cells are abundant Clear cells show small, round to oval monomorphous nuclei; eosinophilic or clear cytoplasm Heavily pigmented spindled and dendritic cells alternate with clear cells Top Differential…
Most commonly on palate, gingiva, or alveolar ridge mucosa Usually single lesion, but on rare occasions, there may be multiple Well-circumscribed, yellow, red, or gray plaque Rough or granular surface…
Symmetric and well circumscribed Often shows dumbbell-like appearance at low power Cells lack prominent cytologic atypia, mitotic activity, and necrosis • Atypical cellular blue nevus Shows overlapping features with cellular blue…
Small, Nevoid AppearanceNevoid melanoma is deceptively symmetrical, mimicking an intradermal nevus on low-power examination. The only clue is hypercellularity (blue appearance) and lack of maturation, which should invoke a closer…
