Poroid hidradenoma: a case report.

Poroid hidradenoma is a variant of the eccrine poroma that belongs to the group of poroid neoplasms. It presents architectural features of hidradenoma, with solid and cystic areas and tumour cells restricted to the dermis, and cytological features of poroid neoplasm such as poroid and cuticular cells. Poroid hidradenoma becomes malignant in less than 1% of cases, but its histologic characteristics may resemble those of malignant neoplasms; thus it is easily misdiagnosed. Twenty percent of poroid hidradenomas occur in the extremities. To date, very few cases of this entity have been reported in the literature. We present a case of poroid hidradenoma in a 35-year-old man with a soft-tissue lesion on his right thigh.