A Case of a Rare Parathyroid Hormone (PTH)-Producing Neuroendocrine Tumor.

BACKGROUND Neuroendocrine neoplasms are commonly seen in association with hormone production, and clinical signs that arise from these hormonal effects often manifest as the first presentation of malignancy. The excess production of parathyroid hormone (PTH) in particular, however, is primarily sporadic (80-85%) in clinical settings. In the context of malignancy, hyperparathyroidism manifestations arise most frequently from non-neuroendocrine pulmonary tumors through a ligand mimicker, parathyroid hormone-related peptide (PHrP). Excess PTH or PTHrP production has been very rarely described in association with gastrointestinal tumors and almost never described as a primary paraneoplastic syndrome from a neuroendocrine tumor (NET) alone. CASE REPORT We present a patient with a prior surgically resected carcinoid tumor who later presented with an elevated parathyroid hormone level, hypercalcemia, and clinical manifestations of primary hyperparathyroidism. She was found to have a low-grade, recurrent neuroendocrine tumor on resection of a parathyroid mass suspected to be a productive adenoma. Despite no longer having parathyroid glands given the extent of resection, her PTH level remained elevated and was rising. Further investigation via repeat sestamibi nuclear scan excluded the possibility of exogenous parathyroid tissue, and subsequent dotatate positron emission tomography/computed tomography (PET/CT) revealed the source of the PTH production: multiple sites of metastatic neuroendocrine tumors producing native PTH. CONCLUSIONS This case highlights the rare possibility of NETs to secrete PTH and the importance of considering early staging with dotatate PET/CT to evaluate the extent of disease. Additionally, our case reveals the importance of considering NET as an alternative etiology for refractory hypercalcemia.

Significance of 18F-Fluorodeoxyglucose Uptake at the Gastroesophageal Junction: Comparison of PET to Esophagogastroduodenoscopy.

BACKGROUND: Positron emission tomography-computed tomography (PET/CT) occasionally reveals unexpected uptake of (18)F-fluorodeoxyglucose ((18)F-FDG) at the gastroesophageal junction (GEJ). The aim of this study was to determine the importance of unexpected (18)F-FDG uptake at the GEJ on PET/CT by correlating this finding with endoscopy results. METHODS: We reviewed medical records from June 2009 to October 2012 to identify patients in our Veterans Affairs Medical Center who had an esophagogastroduodenoscopy (EGD) performed within 6 months of a PET/CT. Metabolic activity at the GEJ was quantified with standardized uptake values (SUV) and correlated with EGD and histopathology results. RESULTS: A total of 219 patients were identified and assigned to one of five groups based upon EGD findings: esophageal malignancy (n = 34), esophagitis (n = 21), Barrett's esophagus (n = 8), other non-malignant disorders (n = 5), and normal (n = 151). The mean SUV Max for the groups was 6.72, 2.47, 2.40, 3.48, and 2.06, respectively. SUV Max and SUV Mean were significantly higher in the esophageal malignancy group than in all other groups (p < 0.001). SUV for patients with high-grade esophagitis was greater than in patients with low-grade esophagitis. A SUV Max ≥ 3.5 was found to predict necessity for EGD with a positive predictive value of 79 %. A SUV Max ≤ 2.2 yielded a negative predictive value of 86 %. CONCLUSION: Differentiation between benign and potentially significant disease at the GEJ may be possible with quantification of incidental (18)F-FDG uptake at PET/CT. Our results suggest thresholds that may help determine need for further endoscopic evaluation in patients with abnormal metabolic activity at the GEJ.