Diffuse large B-cell lymphoma occurring at ileocolonic anastomosis site after right hemicolectomy for colorectal...

Diffuse large B-cell lymphoma is the most common and aggressive type of non-Hodgkin lymphoma, accounting for approximately 30%-40% of cases. It can arise in both nodal and extranodal sites, most commonly in the gastrointestinal tract. Although gastrointestinal diffuse large B-cell lymphoma has been reported, development at a colorectal anastomotic site is extremely rare. A 94-year-old woman with a history of right hemicolectomy for appendiceal adenocarcinoma and prior chemotherapy for B-cell lymphoma involving the left ventricular wall presented with gait instability and severe anemia. Enhanced computed tomography revealed irregular wall thickening at the ileocolonic anastomosis without lymph node or distant metastasis. Colonoscopy showed a friable, stenotic tumor at the anastomotic site. Surgical resection with lymphadenectomy was performed for bleeding control. Histopathological examination demonstrated diffuse proliferation of atypical lymphoid cells positive for CD20 and CD10, supporting a diagnosis of diffuse large B-cell lymphoma. Postoperative chemotherapy was not administered because of advanced age, and no recurrence has been observed to date. This case highlights the importance of considering lymphoma in the differential diagnosis of anastomotic lesions after colorectal surgery because chronic inflammation and mucosal remodeling may contribute to tumor development.