Solitary thyroid nodule: current management.

Clinically, solitary thyroid nodules are common, being present in up to 50% of the elderly population. The majority are benign with thyroid cancer representing an uncommon clinical problem. Investigation should include careful history and examination and thyroid function tests. Toxic or autonomous nodules are rarely malignant and require radionuclide scan for assessment. If euthyroid, then fine needle biopsy provides direct specific information about the cytology of the nodule from which the histology can be inferred. Thyroid 'incidentalomas' are a common management problem. Non-palpable nodules greater than 1.0 to 1.5 cm represent an absolute indication to perform an ultrasound-guided fine needle biopsy. An atypical fine needle biopsy mandates formal diagnostic excision. Because it is not possible to distinguish a follicular carcinoma from a follicular adenoma on cytological grounds alone, this category must simply be interpreted as indicating a follicular tumour and up to 20% will be malignant. Hemithyroidectomy via a 'collar' incision, with submission of the specimen to formal pathological examination, remains the standard of care, with completion total thyroidectomy for cancers other than low risk papillary cancer and 'minimally invasive' follicular cancer without vascular invasion. The issue of whether follicular adenomas can potentially develop into follicular carcinomas has yet to be satisfactorily resolved. The major challenge in the management of the solitary thyroid nodule remains the assessment as to which nodules require surgical excision and which can be followed conservatively.