Abstract
A pathological review of pineal tumors was performed according to the classification by Russell and Rubinstein : I. teratoma 1) atypical teratorna or germinoma 2) typical and teratoid, II. pinealoma 1) pineoblastoma 2) pineocytoma, III. glial and other forms, IV. cysts. In Japan, the incidence of pineal tumors is remarkably higher than in the USA and Europe. It is attributable to the high incidence of teratoma group including germinoma, whereas the rate of true pinealoma, etc. is lower.
A strong similarity between intracranial germinoma, so-called "pinealoma" with a two cell pattern, and seminoma and dysgerminoma was shown by histopathological, ultrastructural, and enzymo-histochemical findings. Therefore, the term "pinealoma" for so called "two cell pattern pinealoma" should not be used, and the term "ectopic pinealoma" is also inappropriate. The interstitial reaction, including granuloma formation and lymphocytic infiltration in germinoma, might be the result of a local immune response to the tumor.
The histologic structure of true pinealoma indicated two directions of differentiation : one toward a similarity to neuroblastoma, and the other toward a similarity to prenatal or mature pineal body. The tumor could thus be classified as pineoblastoma and pineocytoma, according to the degree of pineocytic differention of the tumor cells, using the presence of the club-shaped argyrophllic cell process as cytologic criteria.
