Endodermal cyst arising from the ventral surface of the medulla oblongata: A case report

Abstract

We report a rare case of an intracranial endodermal cyst arising from the ventral surface of the medulla oblongata. A 22-year-old woman was admitted to our institution with a lesion on the ventral surface of the medulla oblongata as visualized on MR imaging. The mass was seen as a hyperdense lesion on CT scanning, as a hyperintense mass on T1-weighted MR imaging, and as a hypointense mass on T2-weighted imaging. Since the lesion was suspected to be an epidermoid cyst, surgery was performed via the retromastoid suboccipital approach, and the tumor was easily and totally resected. Biochemical assay of the resected cyst contents revealed a cholesterol level of 82 mg/d/. Histologically, the cyst wall was composed of a monolayer of stratified or pseudostratified epithelial cells. Most of the cells were ciliated, and a few goblet cells were also seen. Immunohistochemical examination revealed that the cells were positive for EMA, cytokeratin, CEA, and PAS, and therefore the diagnosis of endodermal cyst was made. Intracranial endodermal cysts arising from the ventral surface of the medulla oblongata are rare. To the authors' knowledge, only 4 cases have previously been reported in the literature. The origin, clinical and neuroradiological features, and differential diagnosis of endodermal cysts are discussed.