NEUROENDOCRINE, IMMUNOHISTOCHEMICAL, AND ULTRASTRUCTURAL-STUDY OF PINEAL REGION TUMORS

Thirteen patients with tumors in the pineal region were submitted to p re- and post-operative blood sampling (08:00, 14:00, 20:00, and 02:00 hr) for three or four consecutive days. A single cerebrospinal fluid ( CSF) sample was collected at surgery, and melatonin levels determined. In all patients, serum and CSF beta subunit of human chorionic gonado trophin (beta HCG), carcino embryonic antigen (CEA), and alpha-fetopro tein (AFP) levels were measured. Histology revealed four pineocytomas, one pineoblastoma, four germinomas, one immature teratoma, one pilocy tic astrocytoma, one lymphoma, and one meningioma. Serum and CSF level s of serological biomarkers were normal, except for one of the germino ma cases. In most patients, alteration either in the circadian rhythm or in the melatonin concentration was observed before surgery. In beni gn neoplasms the circadian rhythm was conserved. In pineoblastoma, lym phoma, and three out of four germinomas, melatonin concentrations were undetectable. Tn one case of germinoma, melatonin levels were high, w ith the circadian rhythm being abolished. According to conventional hi stology, all germinomas were similar. Therefore, in a rare case of pin eal germinoma with high melatonin levels, the tissue was subjected to an in depth investigation (immunohistochemical and ultrastructural) in order to determine the pathology and the possible differences from th e other typical germinomas. Results were compared to those provided fr om other pineal neoplasms. Electron microscopy examination detected th e presence of clusters of intermediate filaments and numerous electron dense granules only in the case of a germinoma producing melatonin.