Pleomorphic pineocytoma associated with normal pineal parenchyma: report of a case in a 70-year-old man.

Pineocytomas (PCs) most frequently occur in adults, but only three cases have been reported in women older than 70 years. In PCs, cytologic pleomorphism, accompanied by ganglion cells intensely expressing neuronal markers, has been described and the presence of pleomorphic cells may lead to an erroneous upgrading of the tumor. We report an unusual case of pleomorphic pineocytoma in an older patient who presented with a slowly growing tumor adjacent to residual pineal gland. The immunohistological markers of the tumoral tissue and the remnant normal pineal tissue were evaluated and compared. In the neoplasm, the large number of cells labeled for neuronal markers, including many pleomorphic cells, confirmed previous findings that a neuronal immunophenotype is common in PC. Reactivity for synaptophysin was stronger in the tumor than the pineal gland, whereas neurofilament protein reactivity was stronger in the pineal gland than the tumor. The neoplastic cells, but not the pineal gland, were reactive for chromogranin A. This dense core vesicle-associated protein immunolabeling is an interesting diagnostic marker for PCs, which makes it possible to distinguish normal pineal parenchyma with low or negative expression from tumoral tissue. This case illustrates that, even though PCs are low-grade tumors, they can increase in size and surgery appears a valuable option.