Small intestinal mucosa-associated lymphoid tissue lymphoma with deep ulcer and severe stenosis: A case report

INTRODUCTION: Although eosinophils are commonly present on the mucosa of the gastrointestinal tract, various pathological conditions may cause a secondary increase in eosinophil quantity. PRESENTATION OF CASE: A 78-year-old man was referred to our hospital due to abdominal pain. Examinations revealed an ulcerative lesion with white moss in the terminal ileum and severe stenosis on the oral and anal sides. Tissue biopsies obtained from the ulcer margins showed a predominance of chronic inflammatory cells and abundant eosinophils in addition to lymphocytes/plasma cells. Secondary causes of tissue eosinophilia were suspected; however, the diagnosis could not be confirmed because of atypical endoscopic findings. Partial resection of the ileum was performed for therapeutic and diagnostic purposes. Histopathology of the resected specimen identified a lymphoepithelial lesion with an invasive tendency. While CD20 staining was positive, MUM-1 and Bcl-6 staining were negative. Based on these findings, the lesion was diagnosed as a small intestinal mucosa-associated lymphoid tissue lymphoma (Lugano staging, stage II(1)). DISCUSSION: Hypereosinophilia in this lesion was suggested to be secondary to chronic inflammation due to tumor growth or impaired transit. CONCLUSION: There is a type of gastrointestinal MALT lymphoma showing an invasive tendency. In such cases, it may demonstrate atypical findings and hypereosinophilia in gastrointestinal tissues.