Ileal mucosa-associated lymphoid tissue lymphoma diagnosed after emergency surgery: A case report and literature review.

INTRODUCTION AND IMPORTANCE: Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, also called MALT lymphoma, is one of the entities of marginal zone lymphomas. These lymphomas are originated from indolent B-cell lymphomas and involve many organs such as the gastrointestinal tract, salivary gland, skin, lung, thyroid or breast. Ileal MALT lymphoma is relatively rare and clinical symptoms are usually atypical. CASE PRESENTATION: We report a case of a 99-year-old man who admitted to the emergency department with increasing and colicky periumbilical pain, vomiting and constipation. Non-contrast-enhanced computed tomography suggested small bowel obstruction due to phytobezoar. Intraoperatively, surgeon discovered the tumor at the site of phytobezoar. Histologically, there was a diffuse infiltration comprised of small to medium sized lymphocytes with monocytoid features. Immunohistochemical result confirmed CD20 positive B-lymphocytes and the Ki-67 proliferation index was 10%. Ileal mucosa-associated lymphoid tissue lymphoma was diagnosed based on histological findings and immunohistochemistry. DISCUSSION: MALToma of the gastrointestinal tract is related to chronic antigenic, inflammatory bowel disease and malabsorption syndromes. However, the etiology of ileal MALToma is unclear. Moreover, symptom of ileal MALToma is really not typical and overleaped in the context of small intestinal obstruction. It should be differentiated small intestinal MALToma from immunoproliferative small intestinal disease and an alpha heavy chain disease. CONCLUSION: Ileal MALT lymphoma remains little known in many previous studies. It is really difficult to preoperatively diagnose. The combination of clinical presentation, postoperative histology and immunohistochemistry contribute to diagnosis and carry out appropriate management.