parathyroid gland adenoma
A benign tumor arising from the parenchymal cells of the parathyroid glands. In the vast majority of cases, the tumor involves a single parathyroid gland. It is associated with the symptoms of primary hyperparathyroidism, resulting from the excessive production of parathyroid hormone. It is usually surrounded by a well-defined capsule. Capsular invasion, vascular invasion, and perineural invasion are absent.