Diffuse Large B-Cell Lymphoma Mimicking an Ulcerative Colitis Flare

We present a case of non-Hodgkin lymphoma of the rectum in a 41-year-old African American male with a 1 year history of ulcerative colitis and no previous immunomodulatory therapy. The patient presented with a 10-day history of hematochezia, for which endoscopy was performed with gross findings indicative of ulcerative colitis flare. Tissue biopsy, however, demonstrated significant lymphoid infiltrating regions with histologic findings suggestive of a diffuse large B-cell lymphoma. Non-Hodgkin's lymphoma accounts for less than 1% of all cases of colorectal cancer. Associated risk factors have been previously reported but, were absent in the patient's history. This suggests the possibility of distinct genetic abnormalities inherent to the tumor and/or an underlying germline mutation inherent to the patient that may have contributed to the premature development of diffuse large B-cell lymphoma.