A Hürthle cell is a transformed (
metaplasia
Metaplasia () is the transformation of a cell type to another cell type. The change from one type of cell to another may be part of a normal maturation process, or caused by some sort of abnormal stimulus. In simplistic terms, it is as if the ...
)
thyroid follicular cell with "enlarged
mitochondria
A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...
and enlarged round
nuclei with prominent
nucleoli
The nucleolus (; : nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis. The nucleolus also participates in the formation of signal recognition particles and plays a ro ...
", resulting in
eosinophilia in the
cytoplasm
The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...
.
Oncocyte
An oncocyte is an epithelial cell characterized by an excessive number of mitochondria, resulting in an abundant acidophilic, granular cytoplasm. Oncocytes can be benign or malignant.
Other names
Also known as:
*'' Hürthle cell'' (thyroid gl ...
s in the thyroid are often called Hürthle cells. Although the terms oncocyte,
oxyphil cell, and Hürthle cell are used interchangeably, "Hürthle cell" is used only to indicate cells of thyroid follicular origin.
[Cannon, J. (2011). The Significance of Hurthle Cells in Thyroid Disease. The Oncologist. doi:10.1634/theoncologist.2010-0253]
Diseases
While Hurthle cells can occur in healthy thyroid glands,
they are often associated with
Hashimoto's thyroiditis
Hashimoto's thyroiditis, also known as chronic lymphocytic thyroiditis, Hashimoto's disease and autoimmune thyroiditis, is an autoimmune disease in which the thyroid gland is gradually destroyed.
Early on, symptoms may not be noticed. Over ti ...
and
Graves' disease
Graves' disease, also known as toxic diffuse goiter or Basedow's disease, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyro ...
.
Hürthle cell neoplasms can be separated into
Hürthle cell adenomas (benign tumours) and carcinomas (malignant tumours) arising from the follicular epithelium of the thyroid gland.
The latter is a relatively rare form of differentiated thyroid cancer, accounting for only 3-10% of all differentiated thyroid cancers,
and was formerly considered a subtype of
follicular thyroid cancer. The
mitochondrial DNA
Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondrion, mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the D ...
of Hürthle cell carcinoma contain somatic mutations.
Hürthle cell carcinomas consists of at least 75% Hürthle cells.
Diagnosis
Hürthle cell
adenoma
An adenoma is a benign tumor of epithelium, epithelial tissue with glandular origin, glandular characteristics, or both. Adenomas can grow from many glandular organ (anatomy), organs, including the adrenal glands, pituitary gland, thyroid, prosta ...
s are most likely diagnosed much more frequently than Hürthle cell carcinomas.
Typically a painless thyroid mass is found in patients with this type of cancer.
As expected, patients with carcinoma usually present larger tumors than patients with adenoma. Rarely, the cancer can spread to the lymph nodes.
On few occasions, patients with Hürthle cell carcinoma have distant metastases in the lungs or surrounding bones.
Hürthle cell neoplasms are somewhat difficult to differentiate between being benign or malignant. Since the size and growth pattern of the tumor cannot be used to determine malignancy, although larger tumors have higher incidence of malignancy, Hürthle cell adenomas and carcinomas have to be separated by the presence of both capsular invasion and vascular invasion in the case of carcinomas, or their absence in the case of adenomas.
Tumors displaying only capsular invasion tend to behave less aggressively than those with vascular invasion.
Hürthle cell carcinomas are characterized as either minimally invasive or widely invasive tumors. While the minimally invasive or encapsulated carcinoma is fully surrounded by a fibrous capsule, the widely invasive carcinoma shows extensive area of both capsular and vascular invasion with the leftover capsule typically difficult to identify.
Classification is important since widely invasive tumors can have outcomes with a 55% mortality rate.
The female to male ratio for Hurthle cell adenomas is 8:1, while the ratio is 2:1 for the malignant version.
Hürthle cell cancer tends to occur in older patients. The median age at diagnosis for Hürthle cell carcinomas is approximately 61 years old.
Histology
Hürthle cells arise from the follicular epithelium. A Hürthle cell is larger than a follicular cell, and polygonal with distinct cell borders.
Key features of these
oncocytic cells include a granular
cytoplasm
The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...
that stains eosinophilic (pink on
H&E stain
Hematoxylin and eosin stain ( or haematoxylin and eosin stain or hematoxylin–eosin stain; often abbreviated as H&E stain or HE stain) is one of the principal tissue stains used in histology. It is the most widely used stain in medical diag ...
), which is commonly due to the oncocytes' high content of
mitochondria
A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...
, and a vesicular nucleus with a large nucleolus.
[Schwab, M. (2011). Encyclopedia of Cancer. Encyclopedia of Cancer. doi:10.1016/B0-12-227555-1/00151-9]
Some of these cells can contain up to 5,000 mitochondria, which fills the cytoplasm to the point of nearly excluding other organelles.
This high amount of mitochondria is reported to be a result of mutations in the mitochondrial DNA.
Some scientists have identified these mutations as deletions in the mitochondrial DNA of Hürthle cells found in neoplasms and Hashimoto's thyroiditis.
[Montone, Kathleen T., Zubair W. Baloch, and Virginia A. LiVolsi. "The thyroid Hurthle (oncocytic) cell and its associated pathologic conditions: a surgical pathology and cytopathology review." Archives of Pathology and Laboratory Medicine 132.8 (2008): 1241-1250.]
Treatment
A non-minimally invasive Hürthle cell carcinoma is typically treated by a total
thyroidectomy followed by radioactive iodine therapy.
A Hürthle cell adenoma or a minimally invasive tumor can be treated by a thyroid
lobectomy, although some surgeons will perform a total thyroidectomy to prevent the tumor from reappearing and metastasizing.
A modified radical neck dissection may be performed for clinically positive lymph nodes.
History
The Hürthle cell is named after German histologist
Karl Hürthle, who investigated thyroid secretory function, particularly in dogs. However, this is a misnomer since Hürthle actually described
parafollicular C cells.
The cell known as the Hürthle cell was first described in 1898 by
Max Askanazy, who noted it in patients with
Graves' disease
Graves' disease, also known as toxic diffuse goiter or Basedow's disease, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyro ...
.
[M. Askanazy. Pathologisch-anatomische Beiträge zur Kenntniss des morbus basedowii, insbesondere uber die dabei auftretende Muskelerkrankkung. Deutsches Archiv für klinische Medicin, Leipzig, 1898, 61:118-186.]
See also
*
Adenoma
An adenoma is a benign tumor of epithelium, epithelial tissue with glandular origin, glandular characteristics, or both. Adenomas can grow from many glandular organ (anatomy), organs, including the adrenal glands, pituitary gland, thyroid, prosta ...
*
Oncocytoma
An oncocytoma is a tumor made up of oncocytes, epithelial cell (biology), cells characterized by an excessive amount of mitochondria, resulting in an abundant acidophilic, granular cytoplasm. The cells and the tumor that they compose are often be ...
*
Oxyphil cell
References
External links
EndocrineWebat endocrineweb.com
at hku.hk
Imageat upmc.edu
{{Endocrine gland neoplasia
Cells