Embryonic carcinosarcoma (mixed tumour) of the pineal gland.

The present paper reports on a pineal gland tumour in an 8-year-old male child. Microscopic examination revealed a carcinomatous and a sarcomatous component. The aspect was characteristic of mixed embryonic carcino-sarcoma described in germ cell layer tumours of the gonads and kidney (Wilms' tumour). Ultrastructurally, the mixed character of the tumour was confirmed and also more differentiated elements were found differing from the appearances described in germ cell layer tumours. On the basis of the morphological examination it is concluded that at least in a proportion of the malignant mixed tumours of the pineal gland, their origin is to be found in the local neural elements and not the extraneural ones.