Primary High-Grade Diffuse Large B-Cell Lymphoma of the Cecum: A Report of a Rare Case.

Primary diffuse large B-cell lymphoma (DLBCL) of the colon is rare and most commonly involves the cecum due to its rich lymphoid tissue. Diagnosis is often delayed because symptoms are nonspecific and endoscopic biopsies may be inconclusive. We report a case of high-grade cecal DLBCL in a 22-year-old male patient who presented with right-sided abdominal pain, weight loss, intermittent fever, and night sweats over three months. Examination revealed a palpable right iliac fossa mass, and imaging demonstrated a large cecal lesion with regional lymphadenopathy; however, colonoscopic biopsies were nondiagnostic. The patient underwent right hemicolectomy, and histopathology with immunohistochemistry confirmed high-grade DLBCL (CD20+, CD10+, BCL6+, Ki-67 ≈ 80%). Postoperatively, he developed a wound infection that was managed conservatively before initiating chemotherapy. This case illustrates that, despite its rarity and diagnostic challenges, cecal DLBCL can be successfully treated through a multidisciplinary approach. Clinicians should consider lymphoma in the differential diagnosis of cecal masses in young adults, particularly when B symptoms are present or biopsy results are inconclusive.