Lymphomatoid gastropathy/NK-cell enteropathy involving the stomach and intestine

Lymphomatoid gastropathy (LyGa)/natural killer (NK)-cell enteropathy (NKCE) is recognized as a benign NK-cell lymphoproliferative disease. Due to its histological similarity to NK/T cell lymphoma, it is easy to misdiagnose, leading to unnecessary chemotherapy and poor quality of life. This disease is typically observed in the small and large intestines in North America, whereas almost all cases in Japan occur locally in the stomach. Only 11 LyGa/NKCE cases involving both gastric and intestinal lesions have been reported, and there are few reports providing endoscopic images throughout the gastrointestinal tract. We report a case of LyGa/NKCE involving both the stomach and small and large intestines with detailed upper gastrointestinal endoscopy, colonoscopy, capsule endoscopy and pathology images. Its pathogenesis currently remains elusive, but most patients with LyGa/NKCE in Japan have Helicobacter pylori (H. pylori) infection. Our patient was also positive for H. pylori infection at disease onset, but after receiving eradication therapy, ulcerative lesions in both stomach and intestine regressed and no recurrence was observed. This case suggests a link between the pathogenesis of LyGa/NKCE and H. pylori infection.