A case of malignant nodular hidradenoma

Malignant nodular hidradenoma was first reported by Liu in 1949, and it is an uncommon appendage tumor that presents on head, trunk, or extremities. It has been known as nodular hidradenocarcinoma, malignant clear cell hidradenoma, clear cell hidradenocarcinoma, and accepted as a tumor of the eccrine sweat glands. Histopathologically, tumor is composed of lobulated masses and contains tubular structures with cystic space formation. The cells forming the nest have two populations of clear cells and basophilic polyhedral cells. We report a case of malignant nodular hidradenoma composed of a small proportion of clear cells.