Rare Occurrence of Hypergastrinemia Due to Thoracic Neuroendocrine Tumor: Detection and Characterization by 68Ga-DOTATATE PET/CT.

Hypergastrinemia is a prominent feature of a segment of gastroenteropancreatic neuroendocrine tumors, the gastrinomas, occurring mostly in the gastrinoma triangle. Hypergastrinemia due to a thoracic neuroendocrine tumor is a very rare occurrence, with a paucity of literature elucidating the same. We report a case of thoracic neuroendocrine tumor in a patient who had initially presented with symptoms of peptic ulcer disease of 3-y duration. On evaluation, the patient's fasting serum gastrin levels were found to be raised. Conventional imaging modalities and endoscopic evaluation did not identify the location of a possible gastrinoma or any other mass in the abdomen. In view of the hypergastrinemia, somatostatin receptor-targeted imaging with (68)Ga-DOTATATE PET/CT was undertaken and showed a somatostatin receptor-expressing paravertebral mass next to the thoracic aorta in the left lung. The mass was excised and was histopathologically suggestive of metastatic neuroendocrine tumor (MIB-1 labeling index, 2%). The present case underscores the importance of (68)Ga-DOTATATE PET/CT in both detecting and characterizing a causative lesion missed on contrast-enhanced CT, especially when the lesion is not easily amenable to biopsy.