Primary cerebral rhabdomyosarcoma and the problem of medullomyoblastoma.

A case of primary rhabdomyosarcoma in the right cerebral hemisphere of a 45 year old woman is reported. This was treated by surgical excision but death occurred 10 months after the first symptom. The histogenesis of such a tumour is discussed. The clinical and pathological features of 15 previously reported similar tumours of the CNS are compared. Most of these occurred in the cerebellum in children where they have been regarded as medullomyoblastomas (a variant of medulloblastoma), teratomas, or rhabdomyosarcomas. Few have been recorded in adults and only one previously in the cerebrum. All of these tumours tend to have a short clinical course, although survival time seems to be significantly improved by surgical excision followed by radiotherapy. The remarkable morphological similarities between the tumours are discussed. Argyrophilic fibrils were demonstrated in the present case and in an unrelated rhabdomyosarcoma of the jaw. This observation may invalidate the main criterion used for separating medullomyoblastomas and teratomas from rhabdomyosarcomas in this group of tumours. It is concluded that at present all these tumours should be regarded as rhabdomyosarcomas.