Sweat gland carcinoma is a rare and heterogeneous tumor. These tumors present a challenge for histologic interpretation for many reasons: they have a broad range of microscopic features, a lack of good correlation between histologic classification and biological behaviour, confusing terminology and similarity to metastatic carcinomas. The tumor is most frequently encountered in the axillae where apocrine glands are abundant. A few cases were also reported in other areas, which typically have less apocrine glands. Most apocrine carcinomas have arisen in adults older than 40 years of age, but occasional examples have been reported in young adult and adolescents. We report a pathologic, immunohistochemical and molecular investigation of an apocrine carcinoma in the perianal region. We also discuss the differential diagnosis of other sweat gland lesions with histochemical and immunohistochemical studies, and review the literature on this unusual neoplasm. The patient was a 63-year-old white man who presented a nodular lesion with 2 years duration in the perianal region. The tumor began to enlarge 4 months before the examination. Physical examination revealed a 28×13 mm, well-defined, subcutaneous nodule, which was firm and reddish and was attached to the overlying skin but had good mobility. The clinical diagnosis was angiofibroma and an excisional biopsy was performed. Macroscopically, a 35× 10 mm portion of perianal skin and underlying soft tissue that included a pedunculated lesion of 25×10 mm was received. No evidence of recurrent or metastatic disease was seen after a follow-up period of 36 months. The specimen was processed according to the usual histopathologic techniques and stained with hematoxylin– eosin, periodic acid Schiff’s before and after digestion with diastase, Alcian blue and Perls’ Prussian blue stain.