Cerebello-pontine angle (CPA) lymphoma with perineural extension into the middle fossa: Case report

Background Tumors of the cerebello-pontine angle are most commonly schwannoma and meningioma. Primary central nervous system (CNS) lymphoma usually presents deep within the cerebral hemispheres, occasionally is found in the cerebellum, and rarely occurs in the cerebello-pontine angle. We report a rare case of primary CNS lymphoma involving the right cerebello-pontine angle and the middle cranial fossa mimicking a tentorial meningioma. Methods A 21-year-old woman presented with right sided hearing loss and a facial droop. Computed tomography (CT) and magnetic resonance imaging (MRI) were performed, followed by cerebral angiography to assess vascularity. Results Imaging revealed a bilobed mass involving the right cerebello-pontine angle and middle fossa. The labyrinthine segment of the facial nerve canal was enlarged, and some bony erosion was seen along the petrous bone anteriorly. The mass was hypointense on both T1 and T2-weighted MRI and exhibited heterogenous enhancement. It was distinctly hypovascular on angiography. At surgery, a B-cell lymphoblastic lymphona was found that infiltrated along the 7^th and 8^th nerve complexes into the internal auditory canal. Conclusion Imaging and surgery disclosed a cerebello-pontine lymphoma with perineural extension along the 7^th nerve to reach the middle cranial fossa. Because of the unusual imaging characteristics of this tumor, as well as special considerations with respect to treatment, preoperative consideration of this entity is important in planning direct surgical biopsy rather than an extensive resection.