Case Report: longitudinal immunoglobulin abnormalities preceding IgA-λ MGUS and colonic DLBCL: a case suggesting...

Monoclonal gammopathy of undetermined significance (MGUS) is a common premalignant condition typically associated with progression to plasma cell disorders. Research suggests that MGUS may also coexist with or precede other lymphoid malignancies, potentially reflecting shared mechanisms involving chronic immune dysregulation. We report a 73-year-old man with more than 10 years of long-standing polyclonal immunoglobulin elevation, who subsequently developed IgA-λ MGUS and was later diagnosed with primary colonic diffuse large B-cell lymphoma (DLBCL). Molecular analysis identified mutations in TET2, IDH2, IGLL5, and DUSP2. Rather than indicating a direct clonal transformation, this case may reflect a multistep process involving chronic immune dysregulation and independent or parallel B-cell clonal events. These findings highlight the potential clinical significance of long-standing immunoglobulin abnormalities and suggest the potential value of longitudinal immune and molecular monitoring.