Abstract: Objective To analyze the clinical features, treatment strategies and survival outcomes of extranodal nasal⁃type NK/T⁃cell lymphoma (ENKTCL) cases involving central nervous system (CNS) involvement. Methods The clinical and imaging data of 18 ENKTCL patients with CNS involvement admitted to Beijing Tongren Hospital, Capital Medical University from May 2009 to November 2023 were retrospectively analyzed. Combined with follow⁃up investigation, the clinical features, remission rate and prognosis of patients after treatment were analyzed. Results Among the 18 ENKTCL patients with CNS involvement, the median age was 48 years (range, 33-61 years), with 72.2% (13/5) being male. The median time from initial diagnosis of ENKTCL to CNS involvement was 4 months(range, 1-24 months), 6 patients suffered CNS involvement at the time of initial ENKTCL diagnosis, while the remaining patients  were identified during disease progression. Radiological examinations identified CNS lesion locations in 15 patients. 13 of 16 patients displayed abnormal cerebrospinal fluid (CSF) underwent CSF examinations. Lymphoma cells were detected in the aqueous humor of 2 patients, and lymphoma involvement was identified using optical coherence tomography. In terms of treatment outcomes, 16 patients received high⁃dose methotrexate and pegaspargase⁃based chemotherapy, 2 achieved a complete response, 1 had a partial response and 15 experienced progressive disease. After the median follow⁃up of 11.4 months (range, 1⁃25 months), the median overall survival was 3.5 months. Conclusions CNS involvement in ENKTCL is a rare condition characterized by rapid disease progression and poor prognosis. The comprehensive diagnosis combined with clinical manifestations, the results of radiological and CSF examinations and aqueous humor, it aids in identifying the central lesion, developing an individualized treatment plan, and improving patient prognosis.

Key words:  Extranodal nasal?type NK/T?cell lymphoma, Central nervous system involvement, Clinical features, Treatment efficacy