Objective We investigated the treatments, clinical characteristics, and outcomes of patients with disseminated mucosa-associated lymphoid tissue (MALT) lymphoma.

Methods We retrospectively analyzed 117 consecutive patients with disseminated MALT lymphoma who were treated at Tianjin Medical University Cancer Institute & Hospital between January 2000 and July 2025. We applied the Kaplan–Meier method to the univariate analysis of survival, and assessed differences using the Log-rank test. Multivariate analysis was performed using a Cox proportional hazards model.

Results Disseminated disease was found in 32% of the entire cohort. Among these patients, 67.5% had single-organ involvement, 32.4% presented with multiple mucosal sites, and 30% had involved non-mucosal sites (e.g., liver, kidney, meninges). Compared to patients with localized disease, disseminated cases more frequently exhibit bulky tumor masses, B symptoms, impaired performance status, and markedly elevated β2-microglobulin levels. Systemic chemotherapy was administered to 97.4 % of the patients, and rituximab-containing regimens achieved a 61.5 % complete response rate (CR). After a median follow-up of 33 months, respective three year overall survival (OS) and progression-free survival (PFS) rates were 94 % and 85 %. Multivariate analysis identified an absolute lymphocyte count (ALC) > 1×10⁹/L and a maximum lesion diameter > 6 cm as independent adverse prognostic factors for PFS. Prior hepatitis A virus infection was additionally associated with increased relapse risk.

Conclusions Although disseminated MALT lymphoma is generally associated with favorable outcomes, a subset of cases progresses rapidly. Early recognition of high-risk features is essential for selecting risk-adapted therapeutic strategies.