Lipomatous ependymoma: report of a rare differentiation pattern with a comprehensive review of literature

We report the case of a 13-year-old girl presenting with left-sided hemiparesis, altered sensorium and episodic headache with bouts of projectile vomiting. Imaging revealed a large heterodense intraventricular mass lesion displaying focal calcification and hyperintensity on T1- and T2- weighted fluid attenuated inversion recovery (FLAIR) magnetic resonance images suggesting the presence of intratumoral fat. Histologically, the tumour showed sheets of glial cells, focal perithelial rosettes and individual cells showing fat vacuoles. The morphological impression was of an ependymoma with lipomatous differentiation. Glial fibrillary acid protein (GFAP) immunohistochemistry revealed positivity in the cytoplasmic processes of the tumour cells as well as in the cytoplasmic rim of the cells having an adipocytic appearance. S100 and vimentin were also immunoreactive. Ultrastructural studies confirmed the ependymal differentiation of the tumour and the presence of an osmiophilic fat component confirming the diagnosis. After 1 year of follow-up, the patient presented with similar complaints and MRI evidence of recurrence of the tumour. A comprehensive literature review revealed that half of the reported cases of this pattern recurred suggesting a possibly tenacious clinical course.