A Rare Case of Chronic Lymphocytic Leukemia Transforming Into Waldenström Macroglobulinemia During Ibrutinib Therapy.

Chronic lymphocytic leukemia (CLL) can rarely transform into Waldenström macroglobulinemia (WM), posing diagnostic and therapeutic challenges. The diagnosis of WM requires bone marrow infiltration by lymphoplasmacytic cells and the presence of IgM gammopathy. Immunophenotypic markers include FMC7+, CD19+, CD20+, and CD138+. The MYD88 mutation is characteristic. Symptoms arise from tumor infiltration and monoclonal protein production. Here, we present a case of CLL transforming into WM during treatment with ibrutinib. Given the rarity of such a transformation, this case may serve as a valuable reference, and further investigation is needed to understand the pathology underlying this transformation.