Papillary thyroid cancer overview

# Overview
There is limited information about the historical perspective of papillary thyroid cancer. Papillary thyroid cancer may be classified according to histological subtypes. The most common subtypes include conventional, follicular and tall cell form. The exact pathogenesis of papillary thyroid cancer is not fully understood. Papillary thyroid cancer has been associated with somatic rearrangement of RET protooncogene. On gross pathology, an ill-defined tumor, irregular borders, and firm consistency are characteristic findings of papillary thyroid cancer. There is no unique consensus on the definition of histological subtypes of papillary thyroid cancer. Papillary thyroid cancer is caused by a mutation in the RET gene and BRAF gene. Papillary thyroid cancer must be differentiated from other diseases that cause neck mass, such as branchial cleft cyst, thyroglossal duct cyst, cystic metastasis, multiple neurofibromas, and other thyroid cancers. The incidence of thyroid cancer is approximately 15.8 per 100,000 men and women annually. Papillary cancer incidence has increased by 4.4% per year from 1974 till 2013. The majority of papillary thyroid cancers manifest in individuals between the ages of 20 to 55. It is more common among women, with female to male ratio of approximately 3:1. Common risk factors in the development of papillary thyroid cancer are radiation exposure, family history of thyroid cancer, and iodine deficiency. If left untreated, patients with papillary thyroid cancer may progress to develop metastasis. Common complications of papillary thyroid cancer include vocal cord compression, dysphagia, and dyspnea. The presence of metastasis is associated with a particularly poor prognosis among patients with papillary thyroid cancer. The 10-year survival rate papillary thyroid cancer is 99%. According to the American Joint Committee on Cancer (AJCC) there are 4 stages of papillary 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 involved lymph node regions, and metastasis. Papillary thyroid cancer is primarily diagnosed based on clinical presentation. There are no established criteria for the diagnosis of papillary thyroid cancer. The biopsy is the gold standard test for the diagnosis of papillary thyroid cancer. The most common symptoms of papillary thyroid cancer include swelling in the neck, pain in the front of the neck, and hoarseness of voice. Patients with papillary thyroid cancer usually appear thin and cachectic. Physical examination of patients with papillary thyroid cancer is usually remarkable for thyromegaly, lymphadenopathy and anxiety. Laboratory findings consistent with the diagnosis of papillary thyroid cancer include presence of tumor markers such as thyroglobulin. Thyroglobulin can be used as a tumor marker for well-differentiated papillary thyroid cancer. An x-ray may be helpful in the diagnosis of papillary thyroid cancer. Findings on an x-ray diagnostic of metastasis to the lungs or other tissues. CT scan may be helpful in the diagnosis of papillary thyroid cancer. Findings on CT scan suggestive of papillary thyroid cancer include nodal masses suggesting metastasis to the lymph node. MRI  may be helpful in the diagnosis of papillary thyroid cancer. It may be suggestive of lymph node involvement as the first presentation of papillary thyroid cancer on MRI imaging. Neck ultrasound may be performed to detect papillary thyroid cancer.  Ultrasound imaging findings suggestive of malignant thyroid nodule include microcalcification, peripheral and coarse calcification, solid, hypoechoic nodule, locally invaded nodule, and presence of posterior acoustic shadowing. Treatment options for papillary thyroid cancer differes according to the stage and invasion of the tumor and include surgery, external beam radiation therapy ( EBRT), Thyroid suppression therapy, and targeted therapy. Surgery is the mainstay of treatment for papillary thyroid cancer. Surgical interventions of papillary thyroid cancer include total thyroidectomy and lobectomy. Each of these has its indications.

# Historical Perspective
There is limited information about the historical perspective of papillary thyroid cancer.

# Classification
Papillary thyroid cancer may be classified according to histological subtypes. The most common subtypes include conventional, follicular and tall cell form.

# Pathophysiology
The exact pathogenesis of papillary thyroid cancer is not fully understood. Papillary thyroid cancer has been associated with somatic rearrangement of RET protooncogene. On gross pathology, an ill-defined tumor, irregular borders, and firm consistency are characteristic findings of papillary thyroid cancer. There is no unique consensus on the definition of histological subtypes of papillary thyroid cancer.

# Causes
Papillary thyroid cancer is caused by a mutation in the RET gene and BRAF gene.

# Differential Diagnosis
Papillary thyroid cancer must be differentiated from other diseases that cause neck mass, such as branchial cleft cyst, thyroglossal duct cyst, cystic metastasis, multiple neurofibromas, and other thyroid cancers.

# Epidemiology and Demographics
The incidence of thyroid cancer is approximately 15.8 per 100,000 men and women annually. Papillary cancer incidence has increased by 4.4% per year from 1974 till 2013. The majority of papillary thyroid cancers manifest in individuals between the ages of 20 to 55. It is more common among women, with female to male ratio of approximately 3:1.

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

# Natural history, Complications and Prognosis
If left untreated, patients with papillary thyroid cancer may progress to develop metastasis. Common complications of papillary thyroid cancer include vocal cord compression, dysphagia, and dyspnea. The presence of metastasis is associated with a particularly poor prognosis among patients with papillary thyroid cancer. The 10-year survival rate papillary thyroid cancer is 99%.

# Staging
According to the American Joint Committee on Cancer (AJCC) there are 4 stages of papillary 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 involved lymph node regions, and metastasis.

# Diagnostic Study of Choice
Papillary thyroid cancer is primarily diagnosed based on clinical presentation. There are no established criteria for the diagnosis of papillary thyroid cancer. The biopsy is the gold standard test for the diagnosis of papillary thyroid cancer.

# History and Symptoms
The most common symptoms of papillary thyroid cancer include swelling in the neck, pain in the front of the neck, and hoarseness of voice.

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

# Laboratory Findings
Laboratory findings consistent with the diagnosis of papillary thyroid cancer include presence of tumor markers such as thyroglobulin. Thyroglobulin can be used as a tumor marker for well-differentiated papillary thyroid cancer.

# Chest x-ray
An x-ray may be helpful in the diagnosis of papillary thyroid cancer. Findings on an x-ray diagnostic of metastasis to the lungs or other tissues.

# CT
CT scan may be helpful in the diagnosis of papillary thyroid cancer. Findings on CT scan suggestive of papillary thyroid cancer include nodal masses suggesting metastasis to the lymph node.

# MRI
MRI  may be helpful in the diagnosis of papillary thyroid cancer. It may be suggestive of lymph node involvement as the first presentation of papillary thyroid cancer on MRI imaging.

# Echocardiography or Ultrasound
Neck ultrasound may be performed to detect papillary thyroid cancer.  Ultrasound imaging findings suggestive of malignant thyroid nodule include microcalcification, peripheral and coarse calcification, solid, hypoechoic nodule, locally invaded nodule, and presence of posterior acoustic shadowing.

# Other Imaging Findings
Other imaging studies for papillary thyroid cancer include radioiodine scan, which demonstrates increased uptake of radioactive iodine at the areas of metastases and laryngoscopy which demonstrates vocal cord immobility.

# Other Diagnostic Studies
There are no other diagnostic studies associated with papillary thyroid cancer.

# Medical Therapy
Treatment options for papillary thyroid cancer differes according to the stage and invasion of the tumor and include surgery, external beam radiation therapy ( EBRT), Thyroid suppression therapy, and targeted therapy.

# Surgery
Surgery is the mainstay of treatment for papillary thyroid cancer. Surgical interventions of papillary thyroid cancer include total thyroidectomy and lobectomy. Each of these has its indications.

# Primary Prevention
Effective measures for the prevention of papillary thyroid cancer include avoidance of diets low in iodine and avoidance of radiation exposure.

# Secondary Prevention
There are no established measures for the secondary prevention of papillary thyroid cancer.

# Reference