A single lesion showing features of pigmented eccrine poroma and poroid hidradenoma.J Cutan Pathol. 2008 Apr 16.

Poroid hidradenoma (PH) is a variant of poroma. This entity was defined by Abenoza and Ackerman in 1990. This neoplasm shows architectural characteristics of hidradenoma (tumor cells confined entirely within the dermis in both solid and cystic components) and cytologic characteristics of poroid neoplasm (poroid and cuticular cells, the latter showing ductal differentiation). We herein document a case of single poroid lesion with the features of both eccrine poroma and PH. The patient was a 55-year-old woman with a pigmented nodular lesion on her upper back for 7 years. The histopathologic features of the lesion were consistent with those of eccrine poroma and PH. Unlike most eccrine poromas, this case was pigmented, clinically and microscopically.

Poroid hidradenoma: a case report. In Vivo. 2007 Sep-Oct;21(5):905-7.

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.