Clinical characteristics and outcomes of extranodal marginal zone lymphoma of pulmonary mucosa-associated lymphoid tissue: A single-center retrospective study

Abstract Introduction: Extranodal marginal zone lymphoma of pulmonary mucosa-associated lymphoid tissue (MALT) is a rare, indolent lymphoproliferative disease with atypical imaging features, and its optimal treatment strategy remains undefined. This study aimed to summarize the clinical characteristics and treatment outcomes of this population to provide a theoretical basis for treatment decisions. Methods: We retrospectively collected data on patients diagnosed with pulmonary MALT lymphoma at China-Japan Friendship Hospital from January 2010 onward. Data included demographic characteristics, laboratory tests, imaging results, comorbidities, and treatment plans. Results: This study included 41 patients, 70.7% of whom were female. The median age at diagnosis was 64 years (36-84). The main clinical manifestations included cough with sputum, dyspnea, weight loss, and fever, with a median time from symptom onset to diagnosis of 8.2 months. A total of 29.23% of patients were asymptomatic and diagnosed based on abnormal findings on chest computerized tomography (CT) during physical examination. The reported comorbidities included other lung diseases (n=12), autoimmune diseases (n=9), and other tumors (n=6). The diagnostic methods comprised CT-guided lung biopsy (36.6%), bronchoscopy (31.7%), surgery (22.0%), and others, including bone marrow biopsy or lymph node biopsy (9.7%). The median lactate dehydrogenase (LDH) level was 172.5 U/L (117-332). Among 15 patients who were assessed for M-protein by immunofixation electrophoresis, 10 tested positive, predominantly for IgM. Monoclonal B cells were detected in 3 of 21 patients, with no lymphoma infiltration detected in bone marrow smears or biopsies. Across the 41 patients enrolled, 56.1% (23/41) had Ann Arbor stage IV disease, of whom 12.2% were classified as high-risk according to MALT-IPI. Pulmonary function tests revealed obstructive ventilatory dysfunction in 18 of 24 patients and diffuse ventilatory dysfunction in 13. Imaging revealed diverse abnormalities, including cystic lesions, consolidation, multiple patchy shadows, masses, and ground-glass opacities. The SUVmax of positron emission tomography-computed tomography lesions ranged from 3.9 to 24.2, with a median value of 5.9. A total of 22 patients received systemic treatment. Of these, 14 (63.6%) patients received R-CHOP-like regimens as first-line treatment with an objective response rate (ORR) of 85.7%. Six (22.7%) patients received non-chemotherapy regimens, with an ORR of 50%. Other first-line treatments included rituximab monotherapy, BR, R2, and R+BTKi regimens. With a median follow-up of 21 months, 4 patients experienced disease progression. Second-line treatments included R-CHOP and R+BTKi regimens. The R+BTKi regimen achieved an ORR of 66.7% (3/4). The median time to disease progression was 32 months (12-108). Only one patient with disease progression died, due to severe pneumonia (unrelated to disease progression). Conclusion: Clinical manifestations and imaging features of pulmonary MALT lymphoma patients lack specificity. While immunochemotherapy is commonly used for pulmonary MALT lymphoma, more effective and less toxic treatment strategies are needed.