In June 1997, a 52-year-old man without any medical history was referred to the department of gastroenterology because of gastric subepithelial tumor. Esophagogastroduodenoscopy (EGD) demonstrated 1 cm sized subepithelial tumor on the proximal antrum anterial wall (Fig. 1A). Biopsies showed chronic gastritis only. He was admitted and diagnostic endoscopic mucosal resection was done (Fig. 1B). The pathologic finding was diffuse aggregation of monomorphic lymphoid cells without any large cell or small cell component in the submucosal layer (Fig. 2A, B). Immunohistochemical staining showed atypical lymphoid cells that were positive for pan B and lamda, but negative for pan T, bcl-2 and kappa. Ki-67 labeling index was 5%. These findings suggested his diagnosis was low-grade MALT lymphoma. Abdomen and pelvic computed tomography (CT), chest CT, bilateral bone marrow examination and F-18-fluorodeoxyglucose positron emission tomography (PET) were done and there were no involvement of disease. Although rapid urease test (RUT), serologic test for H. pylori, urea breath test (UBT) and H. pylori culture of gastric mucosa were all negative, he took triple regimen of H. pylori eradication including clarythromycin, amoxicillin, and proton-pump inhibitor (PPI) for 14 days. After the H. pylori eradication was completed, subtotal gastrectomy was done. In the pathologic review of surgical specimen, there were no residual tumor cells. We performed esophagogastroscopy, abdomen and pelvic CT and PET every 6 months for 2 years and then we performed the same examination every 12 months for 4 years. He had been followed without evidence of disease recurrence for 6 years, after which he stopped visiting our hospital. In May 2007, he was referred to our hospital again complaining of throat pain and neck mass. Neck CT showed multiple enlarged lymph nodes in bilateral cervical nodes (Fig. 3A, B). The largest diameter of the involved lymph node was 6 cm. Excisional biopsy showed diffuse infiltration of large atypical lymphoid cells (Fig. 2C, D), which were positive for CD 20, but not for CD 3, CD10, CD 56, ALK-1, or CD 21. Ki-67 labeling index was 90%. These findings suggested DLBCL. EGD and full staging evaluation showed no involvement of other site. He was diagnosed with stage IIA DLBCL and received three cycles of systemic chemotherapy including rituximab, cyclophospamide, doxorubicin, and vincristine (R-CHOP), followed by 3,600 cGy radiotherapy. He achieved and maintained complete remission until recent days.

In June 2005, a 55-year-old woman with hypothyroidism was referred to our department for epigastric discomfort from the department of endocrinology. EGD demonstrated mucosal surface granularity and 1 cm size mucosal elevation which had central depression on the lower body anterior wall (Fig. 1C). Biopsy showed diffuse infiltration of atypical lymphocyte aggregation and glandular invasion of lymphocytes. Immunohistochemical staining showed atypical lymphoid cells that were positive for CD 20 but negative for CD 3, Ki-67 labeling index was 8%. Abdomen CT, chest CT, bilateral bone marrow examination, and PET were done for staging and there were no disease involvement at any other site. Pathologic diagnosis was low grade MALT lymphoma of the stomach at stage IE. RUT and UBT were positive. The patient took H. pylori eradication including clarythromycin, amoxicillin, and PPI for 14 days. Six months later, EGD was followed and confirmed complete histologic remission as well as endoscopic remission. RUT and UBT were all negative. In August 2006, 12 months after the first visit, EGD showed multiple erosions on the proximal antrum (Fig. 1D). Biopsy showed recurred MALT lymphoma and H. pylori was also seen. RUT was positive, too. She took the second eradication of H. pylori infection with the same regimen during the same period of time. In November 2006, she visited our hospital complaining of palpable mass on both the lateral neck. Neck CT showed bilateral cervical lymph node enlargement (Fig. 3C, D). Excisional biopsy showed diffuse infiltration of large atypical lymphoid cells. Immunohistochemical staining was positive for CD 20 and CD 79 but negative for CD 3. Ki-67 labeling index was 80%. These findings suggested DLBCL. In the staging work-up, there was no disease involvement except for both the neck nodes. EGD showed the second complete remission and RUT was negative. She was diagnosed with stage IIA DLBLC and took three cycles of R-CHOP followed by radiotherapy of 3,600 cGr. In April 2007, DLBCL and gastric MALT lymphoma regressed completely. RUT was negative. In December 2008, DLBCL and gastric MALT lymphoma remained in complete remission state and RUT was negative. Until recently she has maintained complete remission state of DLBCL and gastric MALT lymphoma and negative RUT.