[Unusual localisation of rare primary skin carcinoma: a case report]. / Une localisation inhabituelle d'un carcinome primitif cutané rare: à propos d'un cas.

Adnexal carcinomas are rare, accounting for less than 1% of skin carcinomas. Sclerosus carcinoma of the sweat glands was first described by Goldstein et al. in 1982. We here report the case of a 33-year-old female patient with a retracted perianal skin lesion. Histological examination of perilesional skin biopsy, immunohistochemistry, and negative results of laboratory tests, radiological and endoscopic investigations allowed for the diagnosis of eccrine sclerosus carcinoma. This is a rare tumor, usually characterized by facial localization and slow but aggressive progression. It poses problems in differential diagnosis with benign and malignant tumors; hence the challenge encountered by pathologist of suspecting this carcinoma in patients with any sclerotic and infiltrating skin lesion characterized by slow progression, in a context of preservation of the general state and in the absence of neoplastic history as well as of feeling free to ask for new deep biopsies when in doubt.