Mucosa-associated lymphoid tissue lymphoma of the rectum that regressed spontaneously.

We report a case of mucosa-associated lymphoid tissue (MALT) lymphoma of the rectum that regressed spontaneously. A 76-year-old man visited our hospital because of positive faecal occult blood testing. Colonoscopic examination revealed a slightly yellowish protruded lesion with a grooved depression in the lower rectum and two flat elevations in the upper rectum. Microscopic and immunohistological studies led to a diagnosis of MALT lymphoma. As the patient exhibited severe renal dysfunction and angina pectoris, the lesions were left untreated. Three months later, the protruded lesion became flat and the other lesions became unclear. He was followed up closely with endoscopy, but no relapse of these lesions was detected 19 months after the diagnosis.