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).