Background. Pineal parenchymal tumors are rare; therefore, only limited clinical data regarding their behavior is available. This study was performed to provide further information regarding the pathologic features, clinical behavior, and response to therapy of these tumors.
Methods. This study includes data concerning 30 patients (15 male and 15 female patients) with pineal parenchymal tumors (PPT) diagnosed between 1939 and 1991. Based on gross and microscopic features, tumors were divided into four groups: pineocytomas (9); PPT with intermediate differentiation (4); mixed PPT exhibiting elements of both pineocytoma and pineoblastoma (2); and pineoblastomas (15). At the time of diagnosis, four patients had evidence of spinal seeding (two with pineoblastoma, two with PPT with intermediate differentiation). Twenty-two patients received radiation therapy (RT): 6 were treated to local fields, 7 to the whole brain, and 9 to the craniospinal axis.
Results. For patients who received RT and had a minimum follow-up of 6 months, local failure occurred in one of four patients with pineocytomas, zero of four patients with PPT with intermediate differentiation, one of two with mixed PPT, and four of nine (44%) with pineoblastomas. In patients receiving ⩾ 50 Gy to the primary tumor, 0 of 12 had local failure compared with 6 of 7 (86%) patients receiving lesser doses. Leptomeningeal failure occurred in zero of four patients with pineocytomas, zero of four patients with PPT with intermediate differentiation, one of two with mixed PPT, and four of nine with pineoblastomas. All leptomeningeal failures occurred in patients with persistent primary tumor. Of the patients with seeding tumors (PPT other than pineocytomas) one of seven (14%) developed leptomeningeal failure when treated with craniospinal irradiation, compared with four of eight (50%) treated to lesser volumes. The projected 1-year, 3-year, and 5-year survival rates of patients with pineocytomas were 100%, 100%, and 67%, and were 88%, 78%, and 58% for those with the other forms of PPT, respectively.
Conclusions. RT recommendations are described in detail and include the use of doses of ⩾ 50 Gy to areas of gross disease and the administration of craniospinal irradiation in patients with tumors prone to seeding. Surgical, chemotherapeutic, and pathologic considerations are discussed.