Medulloepithelioma with heterologous osteoid component: a case report and review of literature

Medulloepithelioma is a rare brain tumor that has been classified as embryonal tumor with multilayered rosettes (ETMR) if it harbors C19MC amplification. In rare instances, it shows evidence of heterologous differentiation. We report a case of a 10-year-old female who presented with headache, squint, and minimal left sided weakness of 1 week duration. Microscopy revealed a small round blue cell tumor with focal glandular and tubular differentiation. In one focus, well-developed osteoid was identified. The tumor labeled with LIN28A immunostain. Unusual features can be encountered in medulloepithelioma which should be in the differential diagnosis of CNS embryonal tumors. Full description of the case with review of the literature and comparison between cases with and without heterologous elements is presented.