Parathyroid adenoma

Signs and symptoms

The first signs of a parathyroid adenoma and the resulting primary hyperparathyroidism can include bone fractures and urinary calculi such as kidney stones.

Often, a parathyroid adenoma is diagnosed by an incidental finding on blood tests that reveal high calcium levels. Patients may not be experiencing any noticeable symptoms but could be producing excessive amounts of calcium and eventually experience problems later in life if untreated. However, if symptomatic, patients can experience: pain or discomfort in the joints, muscles, and abdomen; depression and mood changes due to the hormonal imbalance.; constipation; exhaustion; and kidney damage.

Genetics

Parathyroid adenoma can be associated with overexpression of the cyclin D1 gene. It is also associated with multiple endocrine neoplasia (MEN).{{cite web |url= https://www.lecturio.com/concepts/multiple-endocrine-neoplasia/| title= Multiple Endocrine Neoplasia

Diagnosis

Hyperparathyroidism is confirmed by blood tests such as calcium and PTH levels. A specific test for parathyroid adenoma is sestamibi parathyroid scintigraphy, often referred to as sestamibi scan or, more colloquially, MIBI scan. This nuclear imaging technique reveals the presence and location of pathological parathyroid tissue. In cases where 99mTc-sestamibi scintigraphy or SPECT delivers inconclusive results, other imaging modalities and tracers can be applied. For detection of multiple parathyroid adenomas, positron emission tomography (PET) using the radiopharmaceutical 68Ga-Trivehexin has demonstrated a higher detection rate (94.1%) than 99mTc-sestamibi imaging (58.8%).

4DCT is used as second line investigation to diagnose parathyroid adenoma. In addition to the three dimensional imaging of a conventional CT scan, 4DCT provides imaging on the changes of iodinated contrast enhancement over time and present them in a video format (from plain imaging to arterial to venous and delay phases). Parathyroid adenoma would show low density on non contrast image, with peak enhancement during the arterial phase, then slowly fade away until the delay phase.

Treatment

Surgery is the only cure for parathyroid adenomas. 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, sometimes parathyroid adenomas can be ablated by ethanol injection, laser or radiofrequency guided by ultrasound.

Micrographs

Image:Parathyroid adenoma intermed mag.jpg Image:Parathyroid adenoma high mag.jpg Image:Parathyroid adenoma histopathology (1).jpg Image:Parathyroid adenoma histopathology (2).jpg Image:Parathyroid adenoma histopathology (3).jpg

References

References

1. (March 2004). "Parathyroid adenoma without hyperparathyroidism". Japanese Journal of Clinical Oncology.
2. (November 2007). "Dynamics of parathyroid hormone secretion in health and secondary hyperparathyroidism". Clinical Journal of the American Society of Nephrology.
3. (2012) The New York Times, Health Guide{{vs. (April 2014)
4. (June 11, 2012). "Parathyroid adenoma: Diagnosis & treatment". Cleveland Clinic.
5. (May 1996). "Cyclin D1/PRAD1 expression in parathyroid adenomas: an immunohistochemical study". The Journal of Clinical Endocrinology and Metabolism.
6. (May 2003). "Sestamibi scanning and minimally invasive radioguided parathyroidectomy without intraoperative parathyroid hormone measurement". Annals of Surgery.
7. (March 2022). "PET/CT imaging of head-and-neck and pancreatic cancer in humans by targeting the "Cancer Integrin" αvβ6 with Ga-68-Trivehexin". European Journal of Nuclear Medicine and Molecular Imaging.
8. (July 2024). "⁶⁸Ga-Trivehexin PET/CT: a promising novel tracer for primary hyperparathyroidism". European Journal of Nuclear Medicine and Molecular Imaging.
9. (January 2014). "How to Perform Parathyroid 4D CT: Tips and Traps for Technique and Interpretation". Radiology.
10. (August 2011). "Minimally-invasive parathyroid surgery". Acta Otorhinolaryngologica Italica.
11. (2012). "Ectopic parathyroid adenoma". Thyroid Research and Practice.