<unk> s (SA) are rare, benign cutaneous adnexal tumors that may progress to become their malignant counterparts, i.e.<unk> rcinomas (SAC). Cutaneous adnexal tumors are a group of skin tumors consisting of tissues that have differentiated (i.e. matured from stem cells) towards one of the four primary adnexal structures found in normal skin: hair follicles, sebaceous sweat glands, apocrine sweat glands, and eccrine sweat glands. SA and SAC tumors were regarded as eccrine gland tumors and termed eccrine<unk> s and eccrine<unk> s, respectively. However, more recent studies have found them to be hair follicle tumors and commonly term them<unk> s and<unk> rcinomas, respectively. Further confusing the situation, SA-like and SAC-like tumors are also 1) manifestations of the inherited disorder, CYLD cutaneous syndrome (CCS), and 2) have repeatedly been confused with an entirely different tumor, adenoid cystic carcinomas of the salivary gland. Here, SA and SAC are strictly defined as sporadic hair follicle tumors that do not include the hereditary CCS<unk> s and heridtary<unk> rcinoms of CCS or the adenoid cystic carcinomas. SA tumors usually occur as slow-growing, single, small, nodular lesions located in the skin of the head, neck, or trunk. SAC tumors develop from benign SA tumors or in very rare cases begin as malignant tumors. SA and SAC tumors must be distinguished from the<unk>  and<unk> ricnoma tumors that develop in individuals afflicted with the CYLD cutaneous syndrome. CCS is an inherited disorder that commonly involves the development of multiple but on occasion a single or few tumors that closely resemble, and may be confused with, the sporadic SA and SAC tumors described here. CCS<unk>  and CCS<unk> rcinoma tumors must be distinguished form the sporadic SA and SAC tumors reviewed here in order to afford genetic counseling to individuals with CCS as well as to the close family members of these individuals. Currently, SA and SAC are usually treated by complete excision making sure that no tumor cells are left behind at the surgical site. This is particularly important in SAC where the incomplete surgical removal of all tumor cells may result in recurrence of the tumor at the surgical site and/or its metastasis to the local lymph nodes draining the surgical site and/or to distant tissues. In addition to surgical resection, some cases of SAC tumors have been treated with adjuvant therapy that includes radiotherapy and/or chemotherapy. It is not clear that these adjuvant treatments improve patient prognoses. Further studies are needed to determine the best treatment(s) for localize SA, localized SAC, and, in particular, metastatic SAC tumors.
Spiradenoma
Dentigerous cyst
Hidrocystoma
Syringoma
Ganglion cyst
Paradental cyst
Mantleoma
Acrospiroma