Waldenström Macroglobulinemia Presenting With Hepatic Lesions: Case Report and Literature Review.

Waldenström macroglobulinemia (WM) is a rare lymphoplasmacytic lymphoma characterized by bone marrow (BM) infiltration and monoclonal IgM secretion. Clinical manifestations most often reflect BM involvement, lymphadenopathy, or splenomegaly, while extramedullary disease is uncommon. Hepatic infiltration usually presents as diffuse hepatomegaly; focal hepatic lesions are exceedingly rare, with only two cases previously reported. We describe a 63-year-old woman with a history of celiac disease who presented with fatigue and pancytopenia. Laboratory testing showed elevated IgM with an IgM-λ monoclonal protein. Imaging revealed multiple hypodense hepatic lesions, splenomegaly, and small-volume lymphadenopathy. BM biopsy demonstrated lymphoplasmacytic lymphoma with λ-restricted plasma cells, and molecular studies were negative for MYD88 L265P and CXCR4 mutations. Liver biopsy showed granulomatous inflammation with necrosis, accompanied by IgM-positive, λ-restricted B cells clonally related to the BM infiltrate, consistent with WM involvement. Sarcoidosis and infectious causes were excluded. The patient received six cycles of bendamustine and rituximab (BR), leading to a reduction in hepatic lesions and IgM levels, though treatment was complicated by persistent cytopenias. This case represents the first reported instance of WM presenting with focal hepatic lesions associated with IgM paraproteinemia and a sarcoid-like granulomatous reaction. Recognition of such atypical presentations is essential, as they may mimic primary hepatic lymphoma, sarcoidosis, or infectious granulomatous disease. Comprehensive histopathological and molecular evaluation is critical for accurate diagnosis and appropriate therapy. Our report expands the spectrum of extramedullary WM and highlights the potential for favorable response to BR despite unusual presentation.