Dermatopathology Flashcards

When evaluating melanoma, which histologic feature is the single most important prognostic factor in the AJCC staging system?

Answer: Breslow depth (tumor thickness)

Breslow thickness (depth in millimeters) is the most important primary-tumor prognostic factor for cutaneous melanoma.

A vascular dermal proliferation of spindle cells with slit-like spaces, extravasated red cells, and HHV-8 positivity is characteristic of which tumor?

Answer: Kaposi sarcoma

Kaposi sarcoma shows slit-like vascular spaces, spindle cells, extravasated erythrocytes, and is HHV-8 positive.

A dermal tumor of small round blue cells shows a paranuclear dot-like CK20 immunostaining pattern. What is the diagnosis?

Answer: Merkel cell carcinoma

Perinuclear dot-like CK20 positivity is characteristic of Merkel cell carcinoma, a neuroendocrine tumor.

Overlying epidermal collarette with a lobular capillary proliferation and a friable rapidly growing lesion describes which entity?

Answer: Pyogenic granuloma (lobular capillary hemangioma)

Pyogenic granuloma is a lobular capillary hemangioma, often with an epidermal collarette at the base.

A benign adnexal tumor shows interconnecting cords of basaloid cells in a 'string of pearls' pattern within a fibrous stroma with ductal differentiation. Which tumor is this?

Answer: Syringoma

Syringoma shows comma-shaped ('tadpole') ducts and basaloid cords with eccrine ductal differentiation in a sclerotic stroma.

Basophilic 'shadow' (ghost) cells with loss of nuclei and calcification are the diagnostic feature of which tumor?

Answer: Pilomatricoma

Pilomatricoma (calcifying epithelioma of Malherbe) is defined by shadow (ghost) cells and dystrophic calcification.

A predominantly lobular panniculitis with vasculitis and evidence of tuberculous hypersensitivity most likely represents which entity?

Answer: Erythema induratum (nodular vasculitis)

Erythema induratum is a lobular panniculitis with vasculitis, classically linked to tuberculous hypersensitivity.