Clinicopathological experience with pineocytomas: report of five surgically treated cases. The clinicopathological experience associated with five cases of pineocytoma is presented. All patients were treated by surgical removal without postoperative radiotherapy. In three individuals, 2000 cGy was administered to the tumor as a presurgical diagnostic test, with no evidence of response. All cases demonstrated histological features of pineocytoma, according to the criteria of Borit et al., and of the so-called "pineocytoma with neuronal differentiation," according to the criteria of Rubinstein. The experience obtained from the present series reveals that these tumors can occur in the initial decades of life, that a cystic appearance and the presence of calcifications are distinctive features of their radiological evaluation, and that they have a good prognosis after surgical removal, even when the histological data indicate local invasion. The convenience of reserving the term "pineocytoma" for these tumors, and of including the so-called "pineocytomas without further differentiation" within the group of pineoblastomas, is suggested in order to achieve a practical clinicopathological assessment of parenchymatous pineal tumors. 