HidradenomaD23.L4

The term "hidradenoma" is historically overused and is used for benign eccrine as well as apocrine tumors (see Hidradenoma papilliferum). The term "hidradenoma" is generally reserved for tumours that are close to the eccrine poroma.

The definition is accepted: benign adnexal tumour with "eccrine" (and apocrine) differentiation, probably originating from a pluripotent stem cell.

The clear cell variant ( clear cell hidradenoma) shows apocrine differentiation, an epidermoid variant shows spindle cell differentiation with trichilemmal or infundibular horn formation, a chondroid variant shows the image of a"chondroid syringoma".

Little characteristic clinical picture. Solitary, asymptomatic, sharply defined, raised, possibly slightly reddened, unpigmented (rarely bluish tinged) 0.3-2.0 cm large (rarely larger) nodule (or nodule) or corresponding plaque.

Dermal, partially subcutaneous, sharply defined, nodular tumour with (not always detectable) broad, multifocal contact zone (juxtaepidermal) to the surface epithelium. Included fibrous or also myxoidal stroma. Cystic parts are differently pronounced.

The tumor parenchyma consists of relatively large, round or cuboid cells with round nuclei of varying chromatin density and a broad, eosinophilic cytoplasm. Isolated cell atypia, mitoses and an increased proliferation activity (Ki-67 label) (Sugiyama A et al. 2007).

Light-cell (clear cell) sections may also be present. Less frequent are tubular differentiations. In tubular formations decapitation phenomena of the luminal cells can be detected (indication of apocrine differentiation).

See the keyword nodular hidradenoma for a comparison with these explanations.

A special variant is the clear cell hidradenoma.

1. Cho S et al (2001) Poroid hidradenoma. Int J Dermatol 40: 62-64
2. Faulhaber D et al (2000) Clear cell hidradenoma in a young girl.J Am Acad Dermatol 42: 693-695
3. Hsu PJ et al (2003) Mixed tubulopapillary hidradenoma and syringocystadenoma papilliferum occurring as a verrucous tumor. J Cutan pathogen 30: 206-210
4. Liu Y (1949) The histogenesis of clear cell papillary carcinoma of the skin. J Am Pathol 25: 151-357
5. Nandeesh BN et al.(2014) A study of histopathologic spectrum of nodular hidradenoma. At J Dermatopathol34: 461-470
6. Sagi A et al (2002) Cystic clear cell hidradenoma of the thumb: case report of a rare hand tumor. Ann Plast Surgery 48: 337-338
7. Sugiyama A et al (2007) Apocrine cystadenoma and apocrine hidrocystoma: examination of 21 cases withemphasis
   on nomenclature according to proliferative features. J Cutan pathogen 34:912-917.
8. Vodovnik A (2003) Coexpression of S-100 and smooth muscle actin in nodular hidradenoma. On J Dermatopathol 25: 361-362