Objective To explore the clinical features and prognosis of pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma.

Methods The clinical characteristics and prognostic factors of 77 patients with pulmonary MALT lymphoma were retrospectively analyzed, all of whom were diagnosed and treated at the Department of Hematology, Zhongshan Hospital, Fudan University from January 2013 to June 2020.

Results The median age of 77 patients was 59 (24-85) years old, with 32 males (41.6%) and 45 females (58.4%). Thirty-two patients (41.6%) were diagnosed due to abnormal examination results, and 45 (58.4%) due to non-specific lung symptoms. According to AnnArbor staging, 14 (18.2%) cases were in stage Ⅰ, 3 (3.9%) cases in stage Ⅱ, 1 (1.3%) case in stage Ⅲ, and 59 (76.6%) cases in stage Ⅳ. 15 cases were followed up for long-term observation with no indication for treatment, 19 cases received surgical treatment, 3 cases received anti-inflammatory treatment, 43 cases received chemotherapy treatment (chemotherapy regimens mainly include RC, R-CHOP, R2, BR, etc.), and 2 patients refused treatment. For the best efficacy after first-line treatment, 25 (32.5%) patients achieved complete remission (CR), 31 (40.2%) achieved partial remission (PR), and 16 (20.8%) patients had stable disease (SD), 2 (2.6%) patients had progressed disease (PD), and the overall response rate was 72.7%. Fourteen patients relapsed and progressed during follow-up after the end of treatment. Up to November 20, 2020, the median follow-up time was 35.31(5.5-96.0) months, the disease-specific median overall survival (OS) time and median progression survival (PFS) were both not yet reached. The 5-year OS rate and 5-year PFS rate were 95.1% and 73.2%, respectively. There was no significant difference in OS and PFS between different stages (Ⅰ/Ⅱ and Ⅲ/Ⅳ; P=0.455 and 0.834). Compared with patients who received local (mainly surgery) treatment, patients in the systemic treatment group (mainly chemotherapy) had better long-term PFS (P=0.04). PFS analysis of different treatment options was further performed in stage Ⅰ/Ⅱ group and the trend was similar. POD24 was available in 53 patients with 7 positive results. POD24 had significant difference in prognosis(P=0.046).

Conclusions The overall prognosis of pulmonary MALT lymphoma is good. There is no significant difference in OS and PFS at different disease stages. Systemic chemotherapy may bring longer benefits, while surgery alone may be associated with poor PFS. POD24 is related to poor overall survival of pulmonary MALT lymphoma.