Eccrine porocarcinoma.

Eccrine porocarcinoma is an extremely rare malignant skin tumor arising from the eccrine sweat duct unit (acrosyringium). It presents histologically with nests of clear tumor cells in the epidermis and superficial dermis. In addition such clear tumor cells lie isolated high up in the epidermis, closely resembling Paget cells. The various tumors, which may originate from the acrosyringium and the histologic differential diagnosis of eccrine porocarcinoma are discussed.