[Malignant nodular hidradenoma--sweat gland tumor]

Malignant hidradenoma is a very rare tumor that originates from sweat glands. We present a 61-year-old man with an ulcerated tumor in his right flank, 4 cm in diameter, that was excised with a wide free margin. Histopathologic study showed an ill-defined, epithelial neoformation, formed by lobules of clear polygonal cells in the deep dermis and subcutaneous tissue, diagnosed as malignant nodular hidradenoma. 1.5 years after excision there was enlargement of the right axillary and inguinal lymph nodes, which showed metastatic, adnexal neoplastic cells. Axillary resection and superficial dissection of the right inguinal nodes were performed. After 3 months the tumor had spread to other lymph nodes and acute obstructive renal failure required insertion of a pig-tail catheter into the right ureter. Radiotherapy was followed by chemotherapy, but he died from end-stage metastatic disease in multi-organ failure.