Chromosomal abnormalities in a pineocytoma.

Tumors of the pineal region represent about 0.4-1% of intracranial neoplasms, including those tumors of germ cell origin (primarily germinomas and teratomas, which represent about 80% of pineal malignancies), and those tumors of the pineal parenchyma (pineocytoma and pineoblastoma). Pineocytoma is composed of relatively mature cells of the pineal parenchyma, whereas pineoblastoma represents a more primitive form resembling medulloblastoma. The rarity of these tumors would account for the scarcity of cytogenetic studies performed on pineocytoma-pineoblastoma; only four cases have been previously reported. Griffin et al. analyzed two pineoblastomas occurring following hereditary retinoblastoma. The first sample displayed abnormalities of chromosome 1: del(1)(p31p21) and der t(1;?)(p36;?), whereas a 1q + and a Dq + chromosome characterized the second sample. Sreekantaiah et al.found a del(11)(q13.1q13.5) as the sole deviation in one pineoblastoma, which also displayed a cell including a del(1)(p31p36) in addition to the 11q -. Finally, Rainho et el. analyzed a pineocytoma characterized by numerical alterations (losses) involving chromosomes X, 5, 8, 11, 14, and 22, and structural rearrangements of chromosomes 1,3, 12, and 22, as follows: inv(1)(p31q44); del(3)(q11); del(12)(q22); del(22)(q11.2).