Clinical history: A 90-year-old man presented to hospital with an erythematous papule on his ankle. A shave biopsy was performed.
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Discussion and answer
Kaposi sarcoma, nodular/tumor stage
The shave biopsy of the skin shows a nodular exophytic tumor. The dermis contains cellular nodules composed of curvilinear fascicles of spindle cells that exhibit mild nuclear pleomorphism and atypia. Occasional mitotic figures are present. The cellular nodules contain slit-like vascular channels and extravasated red blood cells. Hyaline globules are present, some contained within macrophages. The lesion is associated with a mild to moderate lymphoplasmacytic inflammatory infiltrate. Hemosiderin laden macrophages are observed. The spindle cells were strongly positive with D2-40 and faintly positive with anti-CD31.