Central nervous system involvement at initial diagnosis of extranodal NK/T-cell lymphoma: a retrospective study of a consecutive 12-year case series.

Patients with central nervous system (CNS) involvement at initial diagnosis of extranodal NK/T-cell lymphoma (ENKTL) are exceedingly rare, and the clinicopathologic features of CNS involvement have not been well characterized. In this study, we reviewed 662 patients with ENKTL from August 2008 to September 2019. Their clinical and pathological features, treatments, and survival outcomes were analyzed. The median follow-up time was 72 months. Nine of 662 (1.4%) patients were diagnosed with CNS involvement. Among them, the median age was 37 years, and seven patients were male. All patients had positive EBV-DNA, and three patients were asymptomatic at the time of diagnosis with CNS involvement. Common extranodal involved sites included bone, paranasal sinuses, breast, kidney, adrenal gland, and bone marrow. All patients were positive for cytoplasmic CD3ε, cytotoxic granule proteins, and EBER and negative for CD20. All patients received intrathecal chemotherapy and at least one cycle of systemic chemotherapy. Seven patients had died and two were still alive by the last follow-up. The median overall survival (OS) in patients with CNS involvement at initial diagnosis of ENKTL was 9 months, and the 1-year OS was 44.4%. Five patients achieved a complete response after asparaginase-based chemotherapy; two were still alive, one died of systemic progression, one died of ENKTL-associated hemophagocytic syndrome, and one died of treatment-related infections. In conclusion, CNS involvement at initial diagnosis of ENKTL is extremely rare with poor prognosis. There is no standard treatment, and asparaginase-based chemotherapy combined with intrathecal chemotherapy might yield good efficacy.