Lymphomas of the submandibular gland: a nationwide cohort study

Objective: This study explores the epidemiology, incidence, and survival outcomes associated with lymphomas of the submandibular gland (SMG) and examines the influence of autoimmune diseases on these parameters. Methods: This retrospective nationwide cohort study analysed data from patients diagnosed with SMG lymphomas in Denmark between 2000 and 2020. Information was extracted from medical records, the National Pathology Register, and the Danish Lymphoma Database. Survival analyses were conducted using Kaplan-Meier curves, log-rank tests, and Cox proportional hazards models, focusing on lymphoma subtypes and autoimmune diseases. Results: The cohort consisted of 101 patients with a lymphoma diagnosis and involvement of the SMG. Large B-cell lymphoma (LBCL) was diagnosed in 33 cases (32.7%), follicular lymphoma (FL) in 29 cases (28.7%), extranodal marginal zone lymphoma (EMZL) in 27 cases (26.7%), and 12 cases (11.9%) with other subtypes. EMZL had a significantly longer overall survival (OS) compared to other subtypes, with a median OS of 12.4 years (95% CI 11.2–12.4) vs. 8.4 years (95% CI 6.0-12.2). EMZL and FL showed favourable 5-year OS rates of 95% and 89%, respectively. LBCL had a 5-year OS rate of 65%. Age over 60 significantly negatively impacted OS. Traditional poor prognostic indicators did not significantly affect OS. A notable association between EMZL and autoimmune diseases was observed, particularly with Sjögren’s syndrome, indicated by an increased relative risk of 2.67 (CI 95% 0.45–16.01). Conclusions: Lymphomas of the SMG are rare and have ambiguous clinical presentations. This study provides novel epidemiological, clinical, and prognostic information.