Immunohistochemical detection of tumor marker in recurrent clivus enterogenous cyst--case report.

A 26-year-old male presented with recurrence of an enterogenous cyst in the intracranial region 10 years after the first operation. The cyst was drained and the cyst wall partially resected at both operations with good outcome. Histological examination showed a change from one layer epithelium in the first specimen to glandular structures in the second. Alcian blue, periodic acid-Schiff, and immunohistochemical staining for epithelial membrane antigen, S-100 protein antigen, keratin, and carcinoembryonic antigen were used to confirm the accurate diagnosis. Immunohistochemical staining showed CA19-9 antigen was positive in both specimens. The CA19-9 level in the cerebrospinal fluid was extremely high (621.5 U/ml) at the second operation. Patients with enterogenous cyst should be monitored to detect possible recurrence.