Parathyroid adenoma

by Archan Kakadekar MD and Jason K Wasserman MD PhD FRCPC
February 12, 2024

A parathyroid adenoma is a benign (non-cancerous) tumour of the parathyroid gland. It is made up of cells typically found in the parathyroid gland. In contrast to normal parathyroid glands, an adenoma can grow large enough to become noticeable or palpable at the front of the neck. This type of growth is more common in women than men most patients and most patients are over 60 years of age at the time of diagnosis. Parathyroid adenomas produce and secrete excessive amounts of parathyroid hormone, leading to a condition known as hyperparathyroidism.

What are the symptoms of a parathyroid adenoma?

Symptoms of a parathyroid adenoma include involuntary shaking (tremor), nausea, vomiting, abdominal pain, and confusion. These symptoms are caused by high levels of calcium in the blood which develops in response to increased production of parathyroid hormone by the tumour. Hypercalcemia is the medical term used to describe abnormally high levels of calcium in the blood. Hyperparathyroidism is the medical term used to describe high levels of parathyroid hormone in the blood.

What causes a parathyroid adenoma?

Most parathyroid adenomas are sporadic, so doctors do not know what causes them. However, some genetic syndromes such as multiple endocrine neoplasia (MEN) and familial isolated hyperparathyroidism (FIHP), greatly increase a person’s risk for developing these tumours.

What are the microscopic features of a parathyroid adenoma?

Most parathyroid adenomas have two types of cells – chief cells, which appear clear, and oxyphil cells, which appear pink. In an adenoma, these cells tend to form large groups. In contrast, in a normal parathyroid gland, the cells are randomly distributed throughout the gland. In addition, most normal parathyroid glands contain fat. In contrast, very little fat is seen within an adenoma.