Primary central nervous system T-cell lymphoma: a single-centre retrospective study and literature review.

Background: Primary central nervous system T-cell lymphoma (PCNSTL) is an exceptionally rare central nervous system lymphoma with limited clinical data. We present a large case review series of PCNSTL to summarise the clinical characteristics of this disease. Methods: This study integrated 4 new cases of PCNSTL from our centre with 132 previously reported cases identified through a systematic search of PubMed, Cochrane Library and Web of Science databases. Results: A total of 136 PCNSTL cases were identified, with a median age of 41 years (range 2-89 years), and a male-to-female ratio of 1.8:1. Peripheral T-cell lymphoma-not otherwise specified was the most prevalent pathological subtype. Anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALK+ALCL) predominated in men relative to the various subtypes. The cerebral hemispheres are the most frequent anatomical region involved (71.3%), followed by cerebellum (16.2%), basal ganglia (14.7%), brainstem (14.7%), meninges (11.8%) and corpus callosum (2.9%). Meningeal involvement was observed in nearly 50% of ALCL cases. Histopathologically, 31.8% of tumour cells (29/91) were small cell-dominated, 79.2% of the cases presented angiocentric growth pattern (57/72), and half of cases had a positive finding of cerebrospinal fluid (CSF) flow cytometry (7/14). Conclusions: PCNSTL has a male predilection, particularly in ALK+ALCL. PCNSTL shows reduced basal ganglia and corpus callosum involvement relative to primary central nervous system B-cell lymphoma, but displays heightened meningeal tropism, especially in ALCL cases. Histopathological examination typically reveals prominent perivascular lymphocytic cuffing in PCNSTL. CSF flow cytometry could be considered a preferred method for a definite diagnosis of PCNSTL when brain biopsy is not possible.