Primary Duodenal Low-Grade Mucosa-Associated Lymphoid Tissue Lymphoma Presenting with Outlet Obstruction

Low-grade lymphoma arising in mucosa-associated lymphoid tissue (MALT) of the duodenum represents a very rare neoplasm. We report an unusual presentation of primary duodenal MALT lymphoma in a 78-year-old man. The patient initially presented with a suspected pulmonary embolus and was anticoagulated, which precipitated a major gastrointestinal hemorrhage. A large atypical ulcer with narrowing of the duodenum beyond the bulb was seen on endoscopy. Biopsies revealed atypical lymphoid cells. Abdominal CT scan revealed a mass in either the duodenum or head of the pancreas. An endoscopic retrograde cholangiopancreatography (ERCP) was performed, which revealed a normal pancreatic duct with a large calculus in the common bile duct, which was extracted after sphincterotomy. Elective surgery was planned for suspected lymphoma of the duodenum. The patient developed severe nausea, vomiting, and fullness after meals. The patient underwent pancreaticoduodectomy for a neoplastic mass causing duodenal obstruction. Pathological examination of the resected specimen revealed a low-grade B-cell lymphoma (MALToma) arising in the duodenum and invading the pancreas. Flow cytometry confirmed the phenotype typical of MALT lymphoma. Celiac, peripancreatic, pelvic, and cervical nodes were also involved with tumor. Bone marrow was also positive for metastasis. The patient was postoperatively treated with chemotherapy for stage IV disease.