Metastasizing eccrine porocarcinoma. Report of two cases with fatal outcome.

The clinical, histopathological and ultrastructural features of a metastasizing eccrine porocarcinoma are described in a 75-year-old woman and a 82-year-old woman. The previously not recognized tumors were identified by its distinct pattern of metastasis. Metastatic spreading was restricted for years to a circumscribed region of the skin. Histology and electron microscopy disclosed pronounced epidermotropism of the PAS-positive tumor cells. The characteristic pattern of dissemination obviously represents a homing phenomenon of the tumor cells derived from the intraepidermal sweat gland duct.