Primary large B-cell lymphoma involving the cerebellopontine angle mimic acoustic schwannoma: Role of MR Spectroscopy in differential diagnosis. A case report.

Primary central nervous system (CNS) lymphoma is a very rare aggressive non-Hodgkin disease that originates in CNS (brain, leptomeninges, spinal cord, or eyes). It seems to have increased over the last two decades in both immunocompromised and immunocompetent patients. Primary large B-cell lymphoma involving the cerebellopontine angle (CPA) is extremely rare: only 15 cases of large B-cell lymphoma of the CPA have been reported worldwide; based on our knowledge, no cases studied with MR Spectroscopy. Primary large B-cell lymphoma of the CPA must be differentiated from other cerebellopontine angle diseases, such as acoustic neuroma and meningioma. An early and accurate diagnosis of this neoplasm is necessary for the best management because it is a radiosensitive and chemosensitive tumor. Herein, we report a rare case of B-cell lymphoma involving the left CPA in a 65-year-old man who presented with 3 months of hearing loss on the left, illustrated by MR and TC imaging, highlighting how the MR Spectroscopy, thanks to their greater specificity, is decisive in achieving the correct diagnosis of primary lymphoma and differentiating it from acoustic schwannoma or meningioma. Therefore, in the suspicion of a malignant heteroplastic lesion of the CPA, we suggest including Spectroscopy in the MR study protocol.