Malignant tumours of the thyroid
A slow-growing, well-differentiated primary thyroid tumour arising from the thyroid epithelium.
50% of malignant tumours of the thyroid.
Rare after the age of 40 years. Occurs in young adults.
F > M
Presents as a solitary or multifocal swelling of the thyroid. Lymph nodes are palpable in one-third of patients, and may be the only sign when there is a microscopic primary. Papillary tumours spread via lymphatics within the thyroid resulting in multifocal lesions and to neck nodes. Widespread metastases are rare.
Non-encapsulated mass in contrast to adenomas, which have a capsule. There is often infiltration into the surrounding tissue with associated fibrosis.
Patients may be identified during investigation for a solitary thyroid nodule. Definitive diagnosis is by histology, although cytology from fine needle aspiration may indicate malignancy.
Total thyroidectomy with excision of involved neck lymph nodes and preservation of the parathyroid glands. Radical neck dissection is not necessary. Metastases may be treated by resection. Radioactive iodine therapy may
be used prophylactically or as treatment for metastases. Thyroxine replacement is necessary after surgery as replacement and to suppress TSH (in order to reduce the risk of recurrence).
Ten year survival rates of almost 90%. Cervical lymph nodes do not make the prognosis significantly worse, but if the tumour has spread from the thyroid into adjacent structures it has a poor prognosis.