[The question of medullomyoblastoma].

We report a 7 year old female presenting with a primary sarcoma of the frontal cortex, spinal cord metastases, and a cerebellar tumor. The latter was comprised of undifferentiated small cells and a component resembling rhabdomyosarcoma. On formal grounds it could be diagnosed either as medullomyoblastoma or rhabdomyosarcoma. At the ultrastructural level the tumor appeared more typical for a medullomyoblastoma but it seem highly improbable that both (rare) tumors appeared simultaneously by coincidence. Rather, we assume that we are dealing with a metastasis of the sarcoma with differentiation towards rhabdomyosarcoma. The apparent ability of a sarcoma to imitate morphological features of medullomyoblastoma in the cerebellum is further proof of the fact that nosological differentiation of both tumors remains a problem. Our findings did not corroborate the concept of medullomyoblastoma as a separate nosological entity.