A case of signet ring cell carcinoma and mucosa-associated lymphoid tissue lymphoma of the stomach diagnosed simultaneously via magnifying endoscopy with narrow-band imaging.

We present the case of a 57-year-old woman who experienced 3 weeks of intermittent tarry stools and epigastric pain. She had a 25-year history of smoking and a 12-year history of heavy alcohol consumption but had discontinued both 12 years prior. Laboratory investigations revealed elevated anti-H. Pylori IgG antibody levels. Conventional upper gastrointestinal endoscopy revealed two lesions. Magnifying endoscopy with narrow-band imaging showed the characteristic appearance of a diffuse-type gastric cancer 0-IIc lesion with a demarcation line and abnormal vessels ("wavy micro-vessels" and a "cork-screw pattern"). There was also "ballooning" of the crypts and a "tree-like vessel appearance" in an "unstructured area" characteristic of gastric mucosa-associated lymphoid tissue lymphoma with ulceration. Accurate target biopsies were obtained. We performed a laparoscopic total gastrectomy with D1 lymphadenectomy. Pathological examination revealed poorly differentiated stage I adenocarcinoma of the stomach with features of signet ring cell carcinoma as well as stage I mucosa-associated lymphoid tissue lymphoma. In conclusion, we encountered a case of co-existing diffuse-type gastric cancer and gastric mucosa-associated lymphoid tissue lymphoma. Magnifying endoscopy with narrow-band imaging was effective for diagnosing these two co-existing tumors and resulted in the collection of adequate biopsy specimens allowing for an accurate pathological diagnosis and optimal treatment.