Anaplastic thyroid cancer overview

# Overview
In 1811, the first thyroid cancer case was reported. Thyroid cancer was first described by William Stewart Halsted, an American surgeon in the late nineteenth century. Anaplastic thyroid cancer arises from cells of thyroid, which are normally involved in production and secretion of thyroid hormones, thyroxine (T4) and triiodothyronine (T3) and  is always considered as stage IV. Genes involved in the pathogenesis of follicular thyroid cancer include P53 and BRAF. Anaplastic thyroid cancer must be differentiated from other diseases that cause neck masses such as goiter, Grave's disease, Hurthle cell carcinoma, follicular thyroid cancer, papillary thyroid carcinoma, follicular adenoma, sarcoma, and medullary thyroid carcinoma.. Depending on the extent of the tumor at the time of diagnosis, the prognosis of anaplastic thyroid cancer may vary. However, the prognosis is generally regarded as poor. The presence of metastasis is associated with a particularly poor prognosis among patients with anaplastic thyroid cancer. According to the American Joint Committee on Cancer (AJCC) there are 4 stages of anaplastic thyroid cancer based on the clinical features and findings on imaging. Each stage is assigned a letter and a number that designate the tumor size, number of lymph node regions involved, and metastasis. The hallmark of anaplastic thyroid cancer is swelling in the neck. A positive history of irradiation of head and neck, rapid growth of the nodule, and family history of anaplastic thyroid carcinoma is suggestive of anaplastic thyroid cancer. The most common symptoms of anaplastic thyroid cancer include swelling in the neck, pain in the front of the neck, and hoarseness of voice. Surgery is the mainstay of treatment for anaplastic thyroid cancer.

# Historical Perspective
In 1811, the first thyroid cancer case was reported. Thyroid cancer was first described by William Stewart Halsted, an American surgeon in the late nineteenth century.

# Pathophysiology
Anaplastic thyroid cancer arises from cells of thyroid, which are secretory cells that are normally involved in production and secretion of thyroid hormones, thyroxine (T4) and triiodothyronine (T3) and  is always considered as stage IV. Genes involved in the pathogenesis of follicular thyroid cancer include P53 and BRAF.

# Causes
Genetic mutation is suspected to be the main cause of anaplastic thyroid cancer.

# Differential Diagnosis
Anaplastic thyroid cancer must be differentiated from other diseases that cause neck masses such as goiter, Grave's disease, Hurthle cell carcinoma, follicular thyroid cancer, papillary thyroid carcinoma, follicular adenoma, sarcoma, and medullary thyroid carcinoma.

# Epidemiology and Demographics
Females are more commonly affected with follicular thyroid cancer than males. The incidence of follicular thyroid cancer increases with age; the median age at diagnosis is 6th to 7th decades.

# Risk Factors
Common risk factors in the development of anaplastic thyroid cancer are iodine deficiency, family history of thyroid cancer, and radiation exposure.

# Natural history, Complications and Prognosis
Depending on the extent of the tumor at the time of diagnosis, the prognosis of anaplastic thyroid cancer may vary. However, the prognosis is generally regarded as poor. The presence of metastasis is associated with a particularly poor prognosis among patients with anaplastic thyroid cancer.

# Staging
According to the American Joint Committee on Cancer (AJCC) there are 4 stages of anaplastic thyroid cancer based on the clinical features and findings on imaging. Each stage is assigned a letter and a number that designate the tumor size, number of lymph node regions involved, and metastasis.

# History and Symptoms
The hallmark of anaplastic thyroid cancer is swelling in the neck. A positive history of irradiation of head and neck, rapid growth of the nodule, and family history of anaplastic thyroid carcinoma is suggestive of anaplastic thyroid cancer. The most common symptoms of anaplastic thyroid cancer include swelling in the neck, pain in the front of the neck, and hoarseness of voice.

# Physical Examination
Patients with anaplastic thyroid cancer usually appear thin and cachectic. Physical examination of patients with anaplastic thyroid cancer is usually remarkable for thyromegaly, lymphadenopathy and anxiety.

# Laboratory Findings
Laboratory findings consistent with the diagnosis of anaplastic thyroid cancer include elevated T3, elevated T4, and decreased thyroid stimulating hormone.

# Chest x-ray
Chest x ray may be helpful in the diagnosis of anaplastic thyroid cancer.

# CT
CT scan may be helpful in the diagnosis of anaplastic thyroid cancer.

# MRI
MRI  may be helpful in the diagnosis of anaplastic thyroid cancer. MRI may also be performed to detect metastases of anaplastic thyroid cancer to brain and bones.

# Echocardiography or Ultrasound
Neck ultrasound may be performed to detect anaplastic thyroid cancer.

# Other Imaging Findings
PET  may be helpful in the diagnosis of anaplastic thyroid cancer. PET may also be performed to detect metastases of anaplastic thyroid cancer to brain and bones.

# Other Diagnostic Studies
Other diagnostic studies for anaplastic thyroid cancer include laryngoscopy, which demonstrates vocal cord immobility.

# Biopsy
On biopsy, anaplastic thyroid cancer is characterized by trabecular or solid follicular tumor cells that invade tumor capsule and surrounding vascular structures.

# Medical Therapy
Pharmacologic medical therapies for anaplastic thyroid cancer include radioactive iodine therapy and adjuvant radiotherapy.

# Surgery
Surgery is the mainstay of treatment for anaplastic thyroid cancer.

# Prevention
Effective measures for the prevention of anaplastic thyroid cancer include avoidance of diets low in iodine and avoidance of ultraviolet exposure.

# Reference
-   Thyroid Cancer Cancer.gov (2015). #section/_6- Accessed on October, 29 2015
-   Stage Information for Thyroid Cancer  Cancer.gov
(2015). #link/stoc_h2_2- Accessed on October, 29 2015
-   Thyroid Cancer Cancer.gov
(2015). #section/_6- Accessed on October, 29 2015
-   Stage Information for Thyroid Cancer  Cancer.gov
(2015). #link/stoc_h2_2- Accessed on October, 29 2015
-   Thyroid Cancer Canadian Cancer Society (2015). - Accessed on November, 19 2015