Presacral epidermal cyst found in an adult male with a high CEA content: Report of an unusual case

A 63-year-old Japanese man presented with constipation, having noticed flat stools for several years. Digital examination of the rectum, followed by barium enema, colonofiberscopy, computed tomography (CT), and magnetic resonance imaging (MRI) revealed an oval mass located between the retrorectal and presacral space without any mucosal lesion. This mass had narrowed the rectal lumen by compressing the rectum anteriorly. Although the plasma levels of the tumor markers were within the normal range, those of the tumor contents were elevated with a carcinoembryonic antigen (CEA) of 118 ng/mL, while the alpha-fetoprotein (AFP) value was 1 ng/mL. The tumor was completely extirpated through an abdominal incision, and there has been no evidence of recurrence thus far. Histological examination showed that the tumor wall was made of keratinized stratified squamous epithelium without any cutaneous adnexal structure, and hence it was diagnosed as an epidermal cyst. CEA was identified in these benign epithelial cells by immunoperoxidase staining using a monoclonal antibody. To the best of our knowledge, there have been only four other cases with a presacral epidermal cyst documented in the Japanese literature, all of whom were female. Our patient is the first reported case of an adult male with a presacral epidermal cyst.