Hidradenoma refers to a benign adnexal tumor of the apical sweat gland.

It usually presents as a single, small skin-colored lesion, and may be considered closely related to or a variant of poromas.

[3] Hidradenomas are often sub-classified based on subtle histologic differences, for example:[4] Discussion of sweat gland tumors can be difficult and confusing due to the complex classification and redundant terminology used to describe the same tumors.

[2] There has also been a change in understanding about how tumors that were previously believed to strictly derive from specific sweat gland types may, in fact, derive from both eccrine or apocrine glands.

[7] Surgical excision is usually curative and local recurrences are rare, although malignant tumors may metastasize.