Thyroid malignancies are most commonly primary thyroid cancers but can rarely be metastatic deposits.
Epidemiology
Risk factors
- head and neck irradiation (see radiation-induced thyroid cancer)
- family history of thyroid cancer
- age <30 or >60 years
- male
- >2 cm
Pathology
Classification
Thyroid malignancies can be categorized into the following key subtypes:
- primary thyroid cancers
- papillary thyroid carcinoma: 60-80% of carcinomas
- follicular thyroid carcinoma: 10-20%
- medullary thyroid carcinoma: 5%
- anaplastic thyroid carcinoma : 1-2%
-
thyroid lymphoma: ~2.5%
- primary thyroid lymphoma
- secondary thyroid involvement with lymphoma
- metastases to the thyroid: 1%
-
squamous cell carcinoma (rare) 4
- primary
- secondary
- direct invasion from head and neck squamous cell carcinoma
- metastatic disease
- carcinoma showing thymus-like elements (CASTLE) (rare)
Staging
For primary thyroid tumors see: staging of thyroid cancer.
