[Mucosa-associated lymphoid tissue lymphoma of the appendix concomitant with appendicitis:a case report].

An 82-year-old man with abdominal pain was admitted to our hospital. Laboratory tests revealed the following:white blood cells, 14300/μl;serum hemoglobin level, 12.9g/dl;serum C-reactive protein level, 0.38mg/dl;and negative anti-Helicobacter pylori immunoglobulin G test. Abdominal computed tomography revealed a tumor in the appendix along with multiple swollen lymph nodes. Colonoscopy revealed a submucosal tumor (SMT) of approximately 30mm in diameter with central ulceration. However, a tumor tissue specimen could not be obtained for biopsy;thus, the tumor could not be diagnosed. In esophagogastroduodenoscopy, abnormalities or gastric mucosal atrophy was not observed. A rapid urease test yielded negative results. Hence, endoscopic ultrasound-guided fine needle aspiration for the SMT was recommended;however, the patient preferred to undergo a definitive surgery to establish exact diagnosis. Therefore, right hemicolectomy and lymph node dissection (D3) were performed. Histopathologically, the resected tumor specimen showed atypical lymphocytes. Additionally, immunohistochemical evaluation demonstrated positive staining of the tumor cells for CD20 and BCL2 and negative staining for CD34, CD4, CD10, and BCL6. The tumor was finally diagnosed as a stage II2 mucosa-associated lymphoid tissue lymphoma (Lugano classification). Postoperatively, the patient received chemotherapy with four cycles of rituximab based on his age and activities of daily living.