Parathyroid carcinoma is a rare cancer resulting in parathyroid adenoma to carcinoma progression.
[Hu MI, Vassilopoulou-Sellin R, Lustig R, Lamont JP]
"Thyroid and Parathyroid Cancers"
in Pazdur R, Wagman LD, Camphausen KA, Hoskins WJ (Eds
Cancer Management: A Multidisciplinary Approach
11 ed. 2008. It forms in tissues of one or more of the
parathyroid glands (four
pea-sized glands in the neck that make
parathyroid hormone
Parathyroid hormone (PTH), also called parathormone or parathyrin, is a peptide hormone secreted by the parathyroid glands that regulates the serum calcium concentration through its effects on bone, kidney, and intestine.
PTH influences bone r ...
(PTH). PTH helps the body maintain normal levels of serum
calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...
by promoting calcium reabsorption from bone. It is antagonized by the hormone
calcitonin
Calcitonin is a 32 amino acid peptide hormone secreted by parafollicular cells (also known as C cells) of the thyroid (or endostyle) in humans and other chordates. in the ultimopharyngeal body. It acts to reduce blood calcium (Ca2+), opposing ...
, which prompts calcium storage.).
It is rare, with documented cases of less than one thousand since its first discovery in 1904;
and much less common than
parathyroid adenoma.
It can be difficult to excise.
The rate of occurrence of parathyroid carcinoma is between 0.5% to 5%
Signs and symptoms
Most patients experience moderate to severe hypercalcemia and high parathyroid hormone levels. A large mass in the neck is often seen, and kidney and bone abnormalities are common.
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Risk factors
Parathyroid cancer occurs in midlife at the same rate in men and women.
Conditions that appear to result in an increased risk of parathyroid cancer include multiple endocrine neoplasia type 1,[ and hyperparathyroidism-jaw tumor syndrome][ (which also is hereditary).][ Parathyroid cancer has also been associated with external radiation exposure, but, most reports describe an association between radiation and the more common parathyroid adenoma.][
]
Diagnosis
On Sestamibi parathyroid scan, intense radioactivity greater than submandibular gland
The paired submandibular glands (historically known as submaxillary glands) are major salivary glands located beneath the floor of the mouth. They each weigh about 15 grams and contribute some 60–67% of unstimulated saliva secretion; on stimula ...
on delayed image, no washout between early and delayed images, and high concentration of parathyroid hormone concentration in blood in those who age more than 40 years is suggestive of parathyroid carcinoma.thyroid adenoma
A thyroid adenoma is a benign tumor of the thyroid gland, that may be inactive or active (functioning autonomously) as a toxic adenoma.
Signs and symptoms
A thyroid adenoma may be clinically silent ("cold" adenoma), or it may be a functional tumo ...
, and thyroid carcinoma also retains the radiotracer because of high metabolic nature of these diseases.
Treatment
Parathyroid carcinoma is sometimes diagnosed during surgery for primary hyperparathyroidism. If the surgeon suspects carcinoma based on severity or invasion of surrounding tissues by a firm parathyroid tumor, aggressive excision is performed, including the thyroid and surrounding tissues as necessary.[
Agents such as calcimimetics (for example, cinacalcet) are used to mimic calcium and are able to activate the parathyroid calcium-sensing receptor (making the parathyroid gland "think" we have more calcium than we actually do), therefore lowering the calcium level, in an attempt to decrease the hypercalcemia.
]
References
External links
Parathyroid cancer
entry in the public domain NCI Dictionary of Cancer Terms
Parathyroid Carcinoma (Medscape eMedicine)
Cancer Management Handbook: Thyroid and Parathyroid Cancers
{{Endocrine gland neoplasia
Endocrine neoplasia
Rare cancers