A Case of Collision Tumor of MALT Lymphoma and Poorly Differentiated Adenocarcinoma Diagnosed Incidentally After Appendectomy For A Clinical Presentation of Acute Appendicitis. - A Case of Collision Tumor of MALT Lymphoma and Poorly Differentiated Adenocarcinoma Diagnosed Incidentally After Appendectomy For A Clinical Presentation of Acute Appendicitis. - Open Access Pub

This report presents a case of collision tumors of low-grade B-cell lymphoma and poorly differentiated adenocarcinoma in the caceum of a 63-year-old woman. Lymphoma was diagnosed incidentally after appendectomy for a clinical presentation of acute appendicitis. Imaging follow-up demonstrated mesenteric lymphadenopathy and liver lesions, and all surgically resected regional mesenteric lymph nodes and liver biopsy were found to be infiltrated by both mucosa-associated lymphoid tissue (MALT) lymphoma and adenocarcinoma. Systemic chemotherapy was administered for advanced colonic adenocarcinoma with liver metastases. The occurrence of synchronous lymphoma and adenocarcinoma of the colorectal region is rare, and this is a previously unreported case of a patient that was diagnosed during management of acute appendicitis. DOI10.14302/issn.2641-5518.jcci-18-2552 Collision tumors of lymphoma and colorectal adenocarcinoma are rare entities and just a few studies exist 1, 2, 3, 4, 5, 6, 7, 8 in the literature. In the case of mucosa-associated lymphoid tissue (MALT) lymphoma which is now known as marginal zone lymphoma MALT type, the gastrointestinal tract is the most frequently involved extranodal site with the stomach being the most common location 7. Primary lymphoma of the colon is rare, comprising only 0.2% to 1.2% of all colonic malignancies 9, and colonic lymphomas represent 5.6% to 20% of all gastrointestinal lymphomas 10. Furthermore, lymphoma synchronously accompanied by adenocarcinoma of the colon is extremely rare 6. Review of literatures revealed no reports of simultaneous occurrence of colonic adenocarcinoma and MALT lymphoma that was diagnosed during management of acute appendicitis as is presented below. Case Presentation A 63-year-old woman presented to the Department of General Surgery as an outpatient with abdominal pain. Physical examination showed the signs of acute appendicitis and appendectomy was performed. During microscopic examination, a small focus of atypical monotonous lymphoid cell population was seen and the material was sampled totally. The pathological examination revealed MALT lymphoma (Figure 1), with diffuse positivity of cluster of differentiation (CD) 20 (Figure 2), CD 79a and B-cell lymphoma (Bcl- 2) (Figure 3) with just a few CD3 positive lymphoid cells. However, no evidence of adenocarcinoma was found in the appendectomy specimen. After the diagnosis of lymphoma, a complete colonoscopy was planned and this revealed a solid tumoral mass in the caecum measuring 5x4x4 cm. Computed tomography of the abdomen and pelvis revealed