A bulky cecal lymphoma mimicking colorectal cancer.

Colonic involvement by non-Hodgkin lymphoma is uncommon and can closely mimic colorectal adenocarcinoma on endoscopic and radiological grounds. We report the case of a 56-year-old woman presenting with abdominal pain and anemia, in whom colonoscopy revealed a large cecal mass extending into the ascending colon. Histological and immunohistochemical evaluation confirmed diffuse large B-cell lymphoma of non-germinal center phenotype. Staging studies revealed extensive nodal involvement, including supradiaphragmatic lymphadenopathy, establishing stage IV disease inconsistent with a strictly primary colorectal lymphoma. Systemic immunochemotherapy (R-CHOP) was initiated; after four cycles, a partial response was observed on analytical and radiological grounds, without the need for surgery to date. This case highlights the diagnostic challenge posed by bulky cecal masses mimicking colorectal cancer and underscores the importance of adequate biopsy, immunophenotypic characterization, and complete staging to guide appropriate multidisciplinary management.