Primary central nervous system ALK-negative anaplastic large cell lymphoma presenting as an occipital lobe mass: A case report and review of the literature

Primary central nervous system lymphomas (PCNSLs) are rare entities, constituting less than 1.5% of all intracranial malignancies with an estimated incidence of 1 in 100,000 individuals. The majority of non-Hodgkin lymphomas are of the diffuse large B-cell type, with T-cell lymphomas constituting less than 5%. This report documents a 47-year-old right-handed male patient, presenting sub-acutely to the emergency department. Imaging revealed a 3.5 cm left occipital enhancing mass with extensive surrounding vasogenic edema, highly suspicious for a high-grade glial tumor. Histological examination demonstrated a diffuse infiltrate of large pleomorphic lymphoid cells. Immunocytochemistry confirmed an ALK-negative anaplastic large cell lymphoma, comprising mature T-cell neoplasms expressing CD30. This was confirmed by molecular analysis. Extracranial disease was excluded. The entity anaplastic large cell lymphomas is exceptionally rare in the central nervous system.