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
Parathyroid glands are small endocrine glands in the neck of humans and other tetrapods. Humans usually have four parathyroid glands, located on the back of the thyroid gland in variable locations. The parathyroid gland produces and secretes pa ...
(four
pea-sized glands
In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland).
Structure
De ...
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 re ...
(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 to ...
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 the ...
, 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
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 parath ...
.
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.
[
]
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
Multiple endocrine neoplasia type 1 (MEN-1) is one of a group of disorders, the multiple endocrine neoplasias, that affect the endocrine system through development of neoplastic lesions in pituitary, parathyroid gland and pancreas.
It was first d ...
,autosomal dominant familial isolated hyperparathyroidism
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosomes ...
[ 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
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 parath ...
.[
]
Diagnosis
On Sestamibi parathyroid scan
A sestamibi parathyroid scan is a procedure in nuclear medicine which is performed to localize parathyroid adenoma, which causes Hyperparathyroidism. Adequate localization of parathyroid adenoma allows the surgeon to use a minimally invasive surgi ...
, 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.multinodular goitre
A goitre, or goiter, is a swelling in the neck resulting from an enlarged thyroid gland. A goitre can be associated with a thyroid that is not functioning properly.
Worldwide, over 90% of goitre cases are caused by iodine deficiency. The term i ...
, Hashimoto thyroiditis
Hashimoto's thyroiditis, also known as chronic lymphocytic thyroiditis and Hashimoto's disease, is an autoimmune disease in which the thyroid gland is gradually destroyed. Early on, symptoms may not be noticed. Over time, the thyroid may enlarg ...
, 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 tumor ...
, and thyroid carcinoma
Thyroid neoplasm is a neoplasm or tumor of the thyroid. It can be a benign tumor such as thyroid adenoma,Chapter 20 in: 8th edition. or it can be a malignant neoplasm (thyroid cancer), such as papillary thyroid cancer, papillary, follicular thyro ...
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