Papillary adenocarcinoma - Malignant tumours of the thyroid

Malignant tumours of the thyroid

Papillary adenocarcinoma

Definition

A slow-growing, well-differentiated primary thyroid tumour arising from the thyroid epithelium.

Incidence/prevalence

50% of malignant tumours of the thyroid.

Age

Rare after the age of 40 years. Occurs in young adults.

Sex

F > M

Clinical features

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.

Macroscopy/microscopy

Non-encapsulated mass in contrast to adenomas, which have a capsule. There is often infiltration into the surrounding tissue with associated fibrosis.

Investigations

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.

Management

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).

Prognosis

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.