Papillary thyroid cancer overview
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Differentiating Papillary thyroid cancer from other Diseases |
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Diagnosis |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]
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. Papillary thyroid cancer may be classified according to histological subtypes into 4 subtypes: classical/follicular variant, oxyphil cell variant, tall cell variant, and solid cell growth pattern variant. On gross pathology, a painless enlarging mass is a characteristic finding of papillary thyroid cancer. On microscopic histopathological analysis, Orphan Annie eye nuclear inclusions and psammoma bodies are characteristic findings of papillary thyroid cancer. Papillary thyroid cancer is caused by a mutation in the RET gene and BRAF gene. The incidence of papillary thyroid cancer is approximately 16.3/100,000 for women and 5.6/100,000 for men in 2008 in United States. Females are more commonly affected with papillary thyroid cancer than males. The female to male ratio is approximately 3:1. 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 5 year event free survival rate is 51% for stage 4 disease. Surgery is the mainstay of treatment for papillary 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.
Classification
Papillary thyroid cancer may be classified according to histological subtypes into 4 subtypes: classical/follicular variant, oxyphil cell variant, tall cell variant, and solid cell growth pattern variant.
Pathophysiology
On gross pathology, a painless enlarging mass is a characteristic finding of papillary thyroid cancer. On microscopic histopathological analysis, Orphan Annie eye nuclear inclusions and psammoma bodies are characteristic findings 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, and multiple neurofibromas.
Epidemiology and Demographics
The incidence of papillary thyroid cancer is approximately 16.3/100,000 for women and 5.6/100,000 for men in 2008 in United States. Females are more commonly affected with papillary thyroid cancer than males. The female to male ratio is 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 5 year event free survival rate is 51% for stage 4 disease.
Staging
According to the American Joint Committee on Cancer (AJCC)[1] 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.
History and Symptoms
The hallmark of papillary 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 papillary thyroid cancer is suggestive 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.
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 elevated T3, elevated T4, decreased thyroid stimulating hormone, and presence of tumor markers such as thyroglobulin.
Chest x-ray
Chest x-ray are not commonly performed in the diagnosis of papillary thyroid cancer.
CT
CT scan may be helpful in the diagnosis of papillary thyroid cancer.
MRI
MRI may be helpful in the diagnosis of papillary thyroid cancer. MRI may also be performed to detect metastases of papillary thyroid cancer to brain and bones.
Echocardiography or Ultrasound
Neck ultrasound may be performed to detect papillar thyroid cancer.
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
Other diagnostic studies for papillary thyroid cancer include mRNA measurement, which demonstrates residual metastatic disease.
Biopsy
On biopsy, follicular thyroid cancer is characterized by trabecular, solid, follicular tumor cells that invade tumor capsule or surrounding vascular structures.
Medical Therapy
Patients with papillary thyroid cancer are treated with radioactive iodine therapy, hormone therapy and targeted medical therapy.
Surgery
Surgery is the mainstay of treatment for papillary thyroid cancer.
Primary Prevention
Effective measures for the prevention of papillary thyroid cancer include avoidance of diets low in iodine and avoidance of radiation exposure.
Reference
- ↑ Stage Information for Thyroid Cancer Cancer.gov (2015). http://www.cancer.gov/types/thyroid/hp/thyroid-treatment-pdq#link/stoc_h2_2- Accessed on October, 29 2015