Widespread metastatic eccrine porocarcinoma.

Eccrine porocarcinoma is a rare malignant sweat gland tumor arising from the acrosyringium. These lesions can show multiple epidermotropic metastases, however, systemic spread is rare. We describe the case of a 42-year-old African American man who presented in February 1998 with a lesion on the plantar surface of his right foot that was diagnosed as an eccrine porocarcinoma. Subsequently, during the next year, cutaneous metastases developed to his left shoulder and flank. Two years after his initial presentation, he was admitted with an esophageal mass and multiple gastric ulcers. Biopsy specimens of these lesions demonstrated metastatic eccrine porocarcinoma. Further evaluation revealed multiple metastases to lymph nodes, lungs, and brain. Histologic examination revealed nests of basaloid cells with eosinophilic cytoplasm and intracellular ductlike lumina lined by eosinophilic basement membranelike material. These ductular structures where highlighted by immunohistochemical stains for carcinoembryonic antigen, confirming their eccrine differentiation. There were mitotic figures and individual cell necrosis. Although rare, systemic metastases from an eccrine porocarcinoma must enter the differential diagnoses of a tumor mass in such patients.