Metastatic intracranial carcinoid with immunohistochemical observation. Case report.

A case of metastatic carcinoid tumor in the right occipital lobe originating from a primary tumor in the right colon is reported in a 68-year-old man. The tumor had a high bromodeoxyuridine labeling index. Although immunohistochemical studies of the tumor specimen showed positive reactivity for serotonin and somatostatin, blood levels of serotonin and urinary 5-hydroxyindoleacetic acid content were normal. This suggests that coexistence of somatostatin with serotonin in the tumor tissue might lead to inhibition of serotonin release by "autocrine regulation." The neurological complications of carcinoid tumors, including intracranial metastasis, are discussed briefly.