Abstract
RATIONALE: Colonic mucosa-associated lymphoid tissue (MALT) lymphoma is an unusual subtype comprising only 2.5% of all MALT lymphomas. Most cases of colonic MALT lymphoma are diagnosed at an early stage. Therefore, the clinical features of advanced-stage colonic MALT lymphoma have seldom been reported, and the endoscopic findings are not well established. In this study, we report the clinical and endoscopic characteristics of stage IV colonic MALT lymphoma and highlight the importance of repeat biopsy to figure out this rare disease. PATIENT CONCERNS: The patient was a 68-year-old male complaining of hematochezia and lower left quadrant abdominal pain for the past 3 days. DIAGNOSES: The patient had 3 masses and friable mucosal lesions in the colon. With the first colonoscopy and biopsy, he was initially diagnosed as having eosinophilic colitis. However, the first treatment with steroids did not show any response. Because of atypical clinical features and colonoscopic findings, a second colonoscopy and a repeat biopsy were performed, and the results were consistent with colonic MALT lymphoma arising in the colon. The patient was finally diagnosed with stage IV colonic MALT lymphoma accompanied by multiple distant metastases. INTERVENTIONS AND OUTCOMES: The patient started to receive chemotherapy with a combination regimen of cyclophosphamide, vincristine, and prednisolone. The follow-up study after 3 months showed stable disease status based on response evaluation criteria in solid tumors. LESSONS: This case report presents atypical clinical characteristics and colonoscopic findings of stage IV colonic MALT lymphoma. Clinical suspicion and repeat biopsy should be considered to diagnose this rare and diagnostically challenging cancer.