Severe Chronic Diarrhea Secondary to Primary Lymph Node Gastrinoma

Abstract

Introduction: Gastrinoma is the most common type of pancreatic neuroendocrine tumors (PETs). It exists in multiple forms including sporadic and as part of Multiple endocrine neoplasia (MEN-I) syndrome, and can be malignant and metastatic. The majority of sporadic gastrinomas (90%) occur in the gastrinoma triangle with the wall of the duodenum and the pancreas being the most common sites, however ectopic sites have been reported as well. The existence of primary lymph node (LN) Gastrinomas is controversial, even-though it is described by many case reports, and supported by prospective studies. The main challenge is to determine whether it represents a primary tumor or metastasis from an occult primary site. There are some criteria used to diagnose patients with primary LN Gastrinoma, however it remains a diagnosis of exclusion and a carful follow up is always warranted. Case report: 48 year-old female presented with chronic abdominal pain, and severe watery diarrhea causing significant renal insufficiency. She had an extensive blood, stool, radiological and endoscopic workup without explanation of her chronic symptoms. Suspicion of an endocrine cause of her secretory diarrhea warranted testing serum gastrin and Chromogranin, which were elevated and suspicious for Gastrinoma. The diagnosis was confirmed radiologically by Octroetide scan, and Endoscopic Ultrasound (EUS), which showed a lesion in the posterior aspect of the head of the pancreas. Secretin stimulation test confirmed the diagnosis. Screening for MEN-I syndrome was negative. She underwent a surgical intervention for tumor enucleation near the head of pancreas. Samples were sent for histological evaluation and they showed LN with neuroendocrine tumor. No additional lesions were found in the Gastrinoma triangle after carful surgical exploration. The patient improved clinically post-operative, her serum gastrin decreased to normal range and repeated Octroetide scan was negative. Conclusion: The existence of primary LN Gastrinomas is controversial. It remains a diagnosis of exclusion and a carful follow up is warranted, and it should be in the differential diagnosis of severe chronic diarrhea.Table 1: Patient's serum gastric levelFigure 2Figure 3