Primary low grade B-cell lymphoma of colon mimicking inflammatory bowel disease: a case report

Primary lymphoma of colon is rare in clinical practice and sometimes difficult to diagnose. We described a case of primary, low grade B-cell lymphoma of colon, whose clinical pictures were similar to inflammatory bowel disease. Although the colon mucosa showed diffuse infiltration of lymphocytes with lymphoepithelial lesions on endoscopic biopsy, immunohistochemical stains for B- and T-cell markers were negative. However, the diagnosis of lymphoma was established by positive findings on rearrangement of antigen receptor gene. Clinical symptom of blood-tinged diarrhea subsided after six courses of chemotherapy. Follow-up colonoscopy revealed normal colon mucosa. However, biopsy of colon mucosa still revealed mild proliferation of small lymphocytes. This case has drawn our attention that primary colonic lymphoma may clinically simulate inflammatory bowel disease, and gene rearrangement analysis might be helpful in the diagnosis of malignant lymphoma when traditional histological and immunohistochemical studies fail to provide a definite diagnosis.