IMMUNOHISTOCHEMICAL, ULTRASTRUCTURAL, BIOCHEMICAL AND IN-VITRO STUDIES OF A PINEOCYTOMA

Using both tumor specimen and cultured tumor cells, we have studied th e differentiation of a pineocytoma by light and electron microscopy (E M) and immunohistochemical demonstration of glial, neuronal and neuroe ndocrine markers. Only interstitial cells were labeled with anti-glial fibrillary acidic:protein and anti-S100 protein antibodies. Synaptoph ysin, neurofilaments and tau labeling was found in cells forming the p ineocytomatous rosettes. Some cells also bound the anti-tryptophan hyd roxylase antibody (TPOH), but no staining was seen after application o f anti-chromogranin A or S-antigen antibodies. EM provided evidence fo r neurosensory differentiation demonstrating the presence of vesicle-c rowned rodlets, cilia (9+0) and fibrous filaments. In culture, tumor c ells proliferated slowly and showed positive immunolabeling for viment in and TPOH. Expression of mRNA coding for TPOH, serotonin N-acetyltra nsferase, hydroxyindole-O-methyl-transferase and c-myc was found in th e tumor using reverse transcriptase-polymerase chain reaction. These r esults demonstrate neuronal differentiation of this pineocytoma and su ggest that the neoplastic pineal cells are capable of synthesizing ser otonin and melatonin.