Primary Lymph Node Gastrinoma Resulting in Zollinger-Ellison Syndrome

Abstract

Purpose: A 63-year-old man presented with 4 months of non-bloody diarrhea, with 30 bowel movements daily; diarrhea persisted at night while fasting. There was an associated 70-pound unintentional weight loss, along with rare heartburn partially relieved with antacids. Computed tomography of the abdomen revealed a 4.7-cm enhancing mass in the midline adjacent to or arising from the uncinate process of the pancreas. Serum gastrin, obtained off of a proton-pump inhibitor (PPI) was elevated to 1270 pg/mL. Esophagogastroduodenoscopy revealed severe erosive esophagitis and innumerable duodenal bulb and post-bulbar ulcers. Gastric rugae were thickened with large amounts of reaccumulating secretions that had a bedside pH of 3.5. Based on these findings, Zollinger-Ellison syndrome (ZES) was diagnosed. Octreotide scan demonstrated uptake in the lesion seen on CT with no liver lesions. The patient was started on IV PPI with resolution of abdominal pain and diarrhea. Exploratory laparotomy demonstrated, within the gastrinoma triangle, a well-circumscribed 4 x 5-cm mass, which was mobile and not fixed to the pancreas or other adjacent structures. Pancreas and duodenum were palpated extensively with no evidence of occult lesions; the mass was then excised. Pathology with staining determined the tumor to be a primary lymph node (LN) gastrinoma. Post-operatively, diarrhea resolved and there was gradual weight gain. Gastrin level normalized and PPI was eventually discontinued. ZES is caused by the autonomous secretion of gastrin by gastrinomas. Ninety percent of gastrinomas occur in an anatomic area called the gastrinoma triangle, classically in the pancreas or duodenal wall. Surgical resection can result in cure and should be pursued in patients with resectable disease. Not all gastrinomas in LN result from metastatic spread from pancreatic primaries, but rather may be primary LN tumors as shown in our case. This is supported by the absence of gastrinoma in other locations and normalization of gastrin levels postoperatively. Primary LN gastrinomas do not have any distinguishing characteristics compared to other types of gastrinomas. All patients with ZES proceeding to surgery should have detailed exploration to rule out pancreatic or duodenal tumors, as well as routine excision of LNs within the gastrinoma triangle. The existence of primary LN gastrinomas is controversial, although one study suggests they may occur in 10% of ZES cases. They do not occur in MEN 1. They are unique in that they have been cured by lymph node excision alone. This case demonstrates that gastrinomas may develop primarily in LNs rather than the more commonly suspected solid organs.