Primary colonic lymphoma: report of two cases and a literature review.

Primary colonic lymphoma is a very rare malignant tumor with no standard treatment. We report two cases of primary colonic lymphoma successfully treated with surgery and chemotherapy, and chemotherapy alone, respectively. The first case was a 61-year-old woman who presented with abdominal pain of more than 1 month. The patient was diagnosed with a colonic tumor, and immunohistochemical examinations confirmed the initial diagnosis of colonic lymphoma. The patient underwent laparoscopic-assisted right hemicolectomy followed by postoperative adjuvant chemotherapy with the cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) regimen, combined with targeted therapy with rituximab (R-CHOP). The second case was a 78-year-old man who presented with a complaint of abdominal distention for more than 1 year. Diffuse large B-cell lymphoma was definitively diagnosed by immunohistochemical examinations, and the patient underwent systemic chemotherapy with the R-CHOP regimen. Primary colonic lymphoma is a rare type of non-Hodgkin's lymphoma (NHL), and the clinical treatment is not standardized, unlike for many other types of lymphoma. Therefore, treatment is mainly based on the patient's symptoms to determine whether surgery or systemic chemotherapy is appropriate. Rituximab is effective in some patients and may play an important role in the treatment of unresectable or asymptomatic colonic lymphoma.