Primary intraventricular central nervous system lymphoma of lateral ventricle in an immunocompetent patient

Primary CNS lymphoma (PCNSL) is a rare variant of extranodal non-Hodgkin’s lymphoma and accounts for 3%–5% of all primary brain tumors. Their intraventricular location is extremely rare with only a few cases on record so far. All the reported cases showed bilateral ventricular involvement. We report the first case of unilateral lateral ventricle PCNL in a 22-year-old female who presented with intractable vomiting and headaches. Computed tomography (CT) followed by magnetic resonance imaging (MRI) revealed lobulated altered signal intensity lesion in the left temporal horn of lateral ventricle with surrounding peritumoral edema causing midline shift. With these imaging features, the diagnosis of intraventricular meningioma was suggested. Microscopic examination of the excised mass revealed round-to-ovoid tumor cells with scant eosinophilic cytoplasm with large and hyperchromatic nuclei, prominent nucleoli, irregular nuclear membrane, and frequent mitotic figures. The tumor cells are positive for leukocyte common antigen, CD20, CD10, CD43; and were negative for CD3, synaptophysin, chromagranin, pan-cytokeratin (pan-CK), Epstein-Barr virus (EBV), and glial fibrillary acidic protein. The Ki-67 was very high (80%). With these histopathological and immunohistochemistry (IHC) findings, diagnosis of NHL of diffuse large B cell type was rendered.