Case Presentation: A 71-year-old female was transferred from an outside hospital where she was being managed for an AKI following an episode of profuse vomiting and diarrhea. She reported a nine-year history of similar episodes and had received a diagnosis of cyclical vomiting syndrome in the past. She also endorsed 30 lb weight-loss over the past year. At the outside hospital, she was reportedly found to have a high somatostatin level. A subsequent somatostatin receptor scintigraphy showed evidence of a neuroendocrine tumor (NET). On presentation to our hospital, her labs were remarkable for a normocytic anemia, hypokalemia, and hypoalbuminemia. A Gallium-68 PET/CT dotatate scan was performed, which revealed a notably avid 2.1 x 1.6 cm mesenteric lesion in the left mid-abdomen. She underwent surgical exploration, in which an enlarged mesenteric lymph node and a suspicious mass in the body of the pancreas (hypoechoic on intra-operative ultrasound) were identified and resected along with four other suspicious lesions. Pathology revealed low-grade NET of only the mesenteric lymph node, with all other samples negative for tumor. The patient was discharged in stable condition, and at follow up two weeks post-op the patient’s vomiting and diarrhea had resolved.
Discussion: Somatostatinoma is a rare tumor, with an incidence of 1 in 40 million, representing 4% of all NET. Although pathology was unable to specify the type of NET, somatostatinoma was suspected in this patient due to her symptoms and elevated somatostatin level. While somatostatinoma syndrome consists of diabetes mellitus, diarrhea/steatorrhea, gallbladder disease, hypochlorhydria, and weight loss, this syndrome is present in less than 1% of patients. While an occult primary cannot be ruled out, the lack of significant PET avidity elsewhere and the resolution of the patient’s symptoms following resection of the culprit lymph node suggest that this was likely a primary lymph node NET. Primary lymph node NET are rare, with very few cases found in the literature. One case series in 1992 reported eight cases comprising of inguinal, axillary, or submandibular lymph node NET in the absence of an identifiable primary, although primary Merkel cell carcinoma was postulated. Another prospective study of 138 patients with sporadic Zollinger-Ellison syndrome found that 16 (11.6%) had lymph node primary gastrinoma. Disease-free survival was similar in this group compared to primary duodenal and pancreatic gastrinoma. No cases of primary lymph node somatostatinoma were found.
Conclusions: This case illustrates the importance of cultivating a broad differential in evaluating patients with common symptoms of nausea and vomiting, particularly when the symptoms are chronic and associated with concerning features like substantial weight loss. Comprehensive differential considerations may help avoid premature closure when dealing with curable albeit less common diseases. Moreover, this case highlights how new advances in imaging, namely Gallium dotatate PET scans, may aid in diagnosis of atypical presentations of neuroendocrine tumors.