Pathology of the Parathyroid Glands

The parathyroid glands act as primary regulator of calcium homeostasis through secretion of parathyroid hormone. Hyperparathyroidism can be due to autonomously functioning adenoma, hyperplasia, and rarely, carcinoma. Parathyroidectomy is highly effective in achieving durable biochemical cure. Distinguishing single-gland adenoma and multigland hyperplasia is aided by preoperative imaging localization studies. Intraoperative assessment includes frozen section analysis and parathyroid hormone monitoring. Frozen section analysis is accurate in confirming parathyroid tissue but less robust in evaluating its functional status. Recent research into the molecular basis of sporadic and familial hyperparathyroidism has provided insight into pathogenesis of uncontrolled hyperfunctionality of the parathyroid gland. This chapter outlines major categories and histopathology of parathyroid lesions underlying hyperparathyroidism, including parathyroid adenoma, atypical parathyroid adenoma, parathyroid hyperplasia, and parathyroid carcinoma. Syndromes of familial hyperparathyroidism are cataloged in the context of their molecular pathogenesis. Less common lesions covered include parathyroid cyst, parathyromatosis, and metastasis to the parathyroid gland.