Combined Nevi
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…
Sinonasal Melanoma
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…
Cellular Blue Nevi
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…
Verruciform Xanthoma
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…
Malignant Cellular Blue Nevus (Melanoma Arising in Cellular Blue Nevus)
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…
Nevoid Melanoma
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…
Vascular Hamartomas
Port-wine stain usually involving extremity Underlying venous and lymphatic malformations Limb overgrowth with hypertrophy of soft tissue and bone • Blue rubber bleb nevus syndrome Multiple blue-colored, rubbery hemangiomas of skin…
Plexiform Fibrohistiocytic Tumor
Most arise at dermal-subcutaneous interface • Also lower extremity, trunk, head, and neck • Painless, slow-growing mass or plaque • Treatment: Wide surgical excision with negative margins • Local recurrence in up to 40%…
Kaposiform Hemangioendothelioma
Consumptive coagulopathy Thrombocytopenia Highest risk for coagulopathy in retroperitoneal and intrathoracic tumors, but also seen in association with large cutaneous tumors • Rare regional lymph node metastases • No distant metastases reported…
Inverted Type A (Clonal) Nevi
ITAN ClinicalClinically, an inverted type A nevus (ITAN) is compared to other pigmented papules. ITAN has an eccentrically placed dark papule upon an evenly pigmented flat area. The lesional borders…
