Parathyroid adenoma

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]

Synonyms and keywords: Adenoma of parathyroid gland

Overview

A parathyroid adenoma is a benign tumor of the parathyroid gland. Parathyroid adenoma can be associated with overexpression of the cyclin D1 gene. Hyperparathyroidism is confirmed by blood tests such as calcium and parathormone levels. A specific test for parathyroid adenoma is sestamibi parathyroid scintigraphy, the sestamibi scan. Surgery is the only cure for parathyroid adenomas.

Pathophysiology

• A parathyroid adenoma is a benign tumor of the parathyroid gland. It generally causes hyperparathyroidism; there are very few reports of parathyroid adenomas that were not associated with hyperparathyroidism.
• A human being usually has four parathyroid glands located on the back surface of the thyroid in the neck. The parathyroids secrete parathyroid hormone (PTH), which increases the concentration of calcium in the blood by inducing the bones to release calcium into the blood and the kidneys to reabsorb it from the urine into the blood. When a parathyroid adenoma causes hyperparathyroidism, more parathyroid hormone is secreted, causing the calcium concentration of the blood to rise, resulting in hypercalcemia.

Genetics

• Parathyroid adenoma can be associated with overexpression of the cyclin D1 gene.

Micrographs of Parathyroid Adenoma

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Risk Factors

• The following risk factors may increase a person’s chance of developing a parathyroid adenoma:

• Multiple endocrine neoplasia type 1 (MEN 1)
• Familial isolated hyperparathyroidism (FIHP)
• Hyperparathyroidism–jaw tumour (HPT-JT) syndrome
• Radiation therapy to the head or neck

Diagnostic Criteria

Hyperparathyroidism is confirmed by blood tests such as calcium and parathormone levels.

Symptoms

• Fatigue
• Confusion
• Nausea
• Constipation
• Kidney stones
• Muscle aches
• Bone fracture

Other Imaging Findings

• A specific test for parathyroid adenoma is sestamibi parathyroid scintigraphy, the sestamibi scan. This nuclear imaging technique reveals the presence and location of pathological parathyroid tissue.

Imaging Findings

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Treatment

Surgery

• Surgery is the only cure for parathyroid adenomas. It is successful about 95% of the time. Parathyroidectomy is the removal of the affected gland(s). The standard of treatment of primary hyperparathyroidism was formerly a surgical technique called bilateral neck exploration, in which the neck was opened on both sides, the parathyroids were identified, and the affected tissue was removed. By the 1980s, unilateral exploration became more common. Parathyroidectomy can now be performed in a minimally invasive fashion, mainly because imaging techniques can pinpoint the location of the tissue. Minimally invasive techniques include smaller open procedures, radio-guided and video-assisted procedures, and totally endoscopic surgery.
• Before surgery is attempted, the affected glandular tissue must be located. Though the parathyroid glands are usually located on the back of the thyroid, their position is variable. Some people have one or more parathyroid glands elsewhere in the neck anatomy or in the chest. About 10% of parathyroid adenomas are ectopic, located not along the back of the thyroid but elsewhere in the body, sometimes in the mediastinum of the chest. This can make them difficult to locate, so various imaging techniques are used, such as the sestamibi scan, single-photon emission computed tomography (SPECT), ultrasound, MRI, and CT scans.

Related Chapters

• Hyperparathyroidism