Papillary carcinoma of choroid plexus. Light and electron microscopic study.

Two cases of papillary carcinoma, one in a 23-month-old girl and the other in a 25-month-old boy who both died within a relatively short time after operation, were studied histologically and electron microscopically. Both tumors originated in the right trigone of the lateral ventricle and spread widely via the cerebrospinal fluid. Histologically, the tumors consisted mostly of a differentiated papillary architecture closely resembling choroid plexus papilloma. Some carcinoma cells, showing cellular atypism, displayed a multilayer arrangement. The amount and distribution of PAS-, Alcian blue-, or orcein-positive substances on the cell surface and/or in the interstitial elements of the carcinomas differed from that of choroid papillomas examined in our laboratory. Electron microscopically, the carcinoma cells in some areas showed a loss of apical-basal polarity, and the formation of both microvilli and desmosome-like structures was indistinct. Papillary carcinoma is reviewed on the basis of the literature from 1906 till 1980.