Hidrosadenoma of the anal canal: a case report with review of the literature.

Hidrosadenoma of the anal canal is an extremely rare tumour. Only nine cases with similar histologic structure have been described in the literature, most representing tumours resected from the anal or rectal mucosa. We present a case of anal hidrosadenoma with immunohistochemical staining features identifying it as a true sweat gland tumour.