<unk>  refers to a benign adnexal tumor of the apical sweat gland. These are 1–3 cm translucent blue cystic nodules. It usually presents as a single, small skin-colored lesion, and is considered distinct from the closely related poroma.<unk> s are often sub-classified based on subtle histologic differences, for example: * clear-cell<unk>  or acrospiroma * nodular<unk>  or acrospiroma * solid-cystic<unk>  Discussion of sweat gland tumors can be difficult and confusing due to the complex classification and redundant terminology used to describe the same tumors. For example, acrospiroma and<unk>  are synonymous, and sometimes the term acrospiroma is used to generally describe benign sweat gland tumors. In addition, a single lesion may contain a mixture of cell-types. 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.<unk> s are by definition benign, with malignant transformation very rare. When tumors show malignant characteristics, they are known as<unk> rcinoma. Surgical excision is usually curative and local recurrences are rare, although malignant tumors may metastasize. File:Gross pathology of cystic nodular<unk> .Gross pathology of a cystic nodular<unk>  File:SkinTumors-P7150488.Dermal duct tumor File:SkinTumors-P7240522.Acrospiroma, solid type File:SkinTumors-P8080553.Acrospiroma, clear cell type
Hidradenoma
Dermoid cyst
Trichilemmoma
Papillary hidradenoma
Epidermoid cyst
Trichodiscoma
Hidradenocarcinoma
Trichofolliculoma