Follicular adenocarcinoma - Malignant tumours of the thyroid

Follicular adenocarcinoma

Definition

A primary malignancy of the thyroid gland arising from the thyroid epithelium.

Incidence/prevalence

Approximately 20% of cases of thyroid malignancies.

Age

Middle age

Sex

F > M

Clinical features

Typically presents as a solitary thyroid nodule in middle-aged patients.

Investigations

Patients are investigated as for a solitary thyroid nodule. Isotope scanning of the nodule reveals it to be non-functioning or ‘cold’. Definitive diagnosis requires tissue from fine needle aspiration.

Complications

Predominantly haematogenous spread. Twenty per cent of patients have metastases in the lungs, bone or liver.

Macroscopy/microscopy

Resembles a benign solitary thyroid nodule, a round encapsulated mass, but less colloid and more solid in appearance. Histology reveals invasion of the capsule, blood vessels and surrounding gland.

Management

Total thyroidectomy with preservation of the parathyroids is required. All palpable lymph nodes are removed. If these contain tumour, a modified radical neck dissection is required. A postoperative radioisotope scan of the skeleton and neck detects metastases as ‘hot spots’, and further treatment is with radioiodine. Thyroxine is given to suppress TSH secretion, as well as for replacement.

Prognosis

Follicular carcinoma is more aggressive than papillary carcinoma. Ten year survival is 50%. Plasma thyroglobulin levels can be monitored for recurrence.