<unk>  (sometimes alternatively described as poroma) is a term used to refer to a benign adnexal tumor of the apical sweat gland (akral "peripheral" + spiroma "epithelial tumor of sweat gland"). Some authoritative sources use this term as a synonym for poroma, and others use it as a broader designation that includes poroma and hidradenoma. Under the general umbrella of sweat gland tumors derived from the apical portion of the secretory duct, there are several sub-types that are distinct by subtle histologic differences and slightly different clinical presentations. Specific types include:
poromas
hidroacanthoma simplex
dermal duct tumor
hidradenomas (nodular and clear cell sub-types)
Generally, these tumors can be of either eccrine or apocrine or even mixed-type sweat gland origin.<unk> /poromas were traditionally thought to display purely eccrine differentiation, but it is now accepted that these tumors can be variable.  Thus, it is more specific to classify any single tumor as a eccrine/apocrine sub-type of<unk> .  This is in contrast to sub-types that have shown to be more purely eccrine differentiation, such as dermal duct tumors, hidroacanthoma simplex, or eccrine poromas.<unk> s are by definition benign, with malignant transformation very rare.  Surgical excision is usually curative and local recurrences are rare, although malignant tumors may metastasize.
Acrospiroma
Epidermoid cyst
Sebaceoma
Spiradenoma
Ganglion cyst
Malignant acrospiroma
Hidrocystoma
Sebaceous cyst