Mesenteric Mass Causing Bowel Obstruction in Waldenström Macroglobulinemia

Waldenström macroglobulinemia (WM) is a rare, indolent lymphoplasmacytic lymphoma characterized by bone marrow infiltration and monoclonal immunoglobulin M (IgM) production. While WM is usually characterized by slow clinical progression, the occurrence of abdominal masses leading to intestinal obstruction is an exceptional manifestation. We report the case of a 62-year-old man referred for evaluation of a pulmonary lesion, with positron emission tomography-computed tomography (PET-CT) findings suggestive of a systemic lymphoproliferative process involving the abdomen and mesentery. Bone marrow immunophenotyping confirmed WM, and histological examination of an abdominal mass revealed a low-grade B-cell non-Hodgkin lymphoma. Initial treatment with bendamustine and rituximab was started. However, the patient developed recurrent abdominal cramps, weight loss, and progressive signs of bowel obstruction, culminating in a laparoscopic segmental enterectomy. Histopathology of the resected specimen demonstrated transmural intestinal ischemia and fibrosis, but no residual lymphoma. Postoperatively, the patient had an uneventful recovery with resolution of symptoms. This case highlights a rare and severe gastrointestinal complication of WM requiring surgical intervention despite early chemotherapy. It emphasizes the importance of a multidisciplinary approach when managing atypical presentations of hematologic malignancies.