Mantle cell lymphoma of the rectum at an early stage: A case report

We report a very rare early-stage case of mantle cell lymphoma, which arose from the rectum. A 60-yearold man presented with a small elastically hard polypoid lesion in the rectum. The lesion was 1.2x1.2cm in size. As a preop eratively barium enema and endoscopy suggested a benign tumor of the rectum , he underwent local excision of a rectal polypoid mass transanally under s pinal anesthesia. However, histological examination revealed a malignant ly mphoma, because the lesion was histologically characterized by solid growth s of small to medium-sized round cells. Furthermore, immunohistochemical te sts revealed B-cell marker positivity and CD5 positivity, but cyclin D1 neg ativity. Since it was reported that lymphomas with a mantle cell lymphoma m orphology and CD5 expression, but without cyclin D1 overexpression, exist i n about 10% of mantle cell lymphoma cases, we diagnosed his disease as mant le cell lymphoma. To our knowledge, this is the first reported case of an early-stage mantle cell lymphoma, originating from the rectum.