Mature cystic teratoma of the right cerebellopontine angle: a rare case report

Background and importance Intracranial mature cystic teratomas are benign neoplasms that commonly occur at the midline. Mature cystic teratomas at the cerebellopontine (CP) angle are very rare. They are unique germ cell tumours curable by safe total surgical resection and have good prognosis. This case report documents the clinical, radiological, histological features and operative findings of mature cystic teratoma at CP angle. Clinical presentation We present a rare case of a mature cystic teratoma at the CP angle in a 24-year-old woman who presented with brainstem compression and cranial nerve deficits. Brain MRI showed atypical findings like hyperintense areas in both T1 and T2 weighted images, calcification and diffusion restriction in part of the lesion. She underwent near total resection of the tumour via right retrosigmoid approach. Intraoperatively, the lesion was intra-arachnoidal unlike schwannomas and the cyst contained sebum-like material, fibrous areas with calcification which are unusual features of common CP angle tumours. Histopathological examination showed well differentiated mature tissues from all three germinal layers and confirmed the diagnosis of a mature cystic teratoma arising from the right CP angle. Patient had good outcome with neurologic recovery. Conclusions Mature cystic teratoma is a rare clinical entity and should be considered in patients with CP angle tumours when there are atypical findings in brain MRI imaging. Cysts with sebum-like material, fibrous areas with calcification and poor tumour-arachnoid plane intraoperatively strongly suggest the possibility of mature cystic teratoma.