Nodular Kaposi's Sarcoma | Dermatopathology

Kaposi's sarcoma is an HHV-8 driven angioproliferative disease. Four types are described and include: classic form, endemic, iatrogenic (typically arising in the setting of immunosuppressive drug therapy) and AIDS-associated. Clinically, the lesions can appear red/blue or brown and assume the form of a macule, plaque or nodule. The microscopic appearance is variable and can range from irregular, dissecting vascular channels to sheets of epithelioid or spindled cells with slit like spaces, attendant RBC extravasation and occasional vascular lumens. PAS positive hyaline globules (representing RBC degradation products) and a lymphoplasmacytic infiltrate are commonly seen as well.

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Slide 1: There are coalescing nodules within the dermis associated with ulceration. 90 year-old man with a right ankle ulcerated mass.

Slide 2: The tumor is composed of tight short fascicles of spindled cells that assume a vaguely storiform growth pattern.

Slide 3: When polarized, exogenous material is easily appreciated.

Slide 4: Significant red cell extravasation is identified. There is a background of lymphocytes and plasma cells. Numerous mitotic figures are noted. The tumor cells are uniform with spindled to oval nuclei, small nucleoli and moderate eosinophilic cytoplasm.

Slide 6: As well the neoplastic cells stain positively for D2-40 while cytokeratin is negative (not shown). The findings are highly characteristic for Kaposi's sarcoma, consistent with the nodular variant.