Adnexal skin tumors in Zaria, Nigeria

Adnexal skin tumors share many features in common and differentiate along one line. Their detailed morphological classification is difficult because of the variety of tissue elements and patterns seen. They may be clinically confused with other cutaneous tumors. The aim of this report is to review and classify all adnexal tumors seen in a pathology department over a 16-year period.

A 16-year retrospective analysis of all adnexal skin tumors seen in a large University Teaching Hospital in Nigeria from January 1991- December 2006. All tissue specimens were fixed in 10% formalin, processed in paraffin wax and stained with Haematoxylin and Eosin. Histology slides were retrieved, studied and lesions characterized.

Fifty-two adnexal tumors were seen, accounting for 0.9% of all cutaneous tumors seen within the same period. The median age was 33 years (range: 4 days-70 years). Clinical presentations varied from discreet swellings and nodules to ulcerated masses. Five patients presented with recurrent lesions. Only two cases had a clinical diagnosis of adnexal tumor. Twenty-four (46%) of the lesions were distributed in the head and neck region. Duration of symptoms was 2 months to 15 years (median: 12 months). Tumours of the sweat gland were the commonest--41 (78.8%); they comprised predominantly eccrine acrospiroma (17), characterized histologically by solid nests of round to polygonal cells with clear to eosinophilic cytoplasm, forming tubules in areas. Tumours of sebaceous gland were 7 (13.5%); they comprised mainly Nevus sebaceous of Jadassohn (6), composed of immature sebaceous glands and pilar structures microscopically and a solitary sebaceous adenoma. Tumours of hair follicle were 4 (7.7%) and included trichoepithelioma, characterized microscopically by multiple horn cysts and epithelial tracts connecting abortive pilar structures and a trichofolliculoma. Forty-six lesions (88.5%) were benign and six (11.5%) malignant.

Adnexal skin tumors have distinct histological patterns which differentiates them from other cutaneous tumors. They are commonly distributed in the head, neck and trunk. The commonest variants are those of eccrine sweat gland origin. Malignant adnexal tumors are uncommon in our setting.