Nodular thyroid disease is common. Ultrasound examination of the neck for a variety of reasons has revealed a linear increase in the prevalence of thyroid nodules from negligible at 15 years to 50% by the age of 60. Only 10% of these nodules are palpable by experienced examiners. Conversely, 50% of patients referred to a thyroid clinic with an apparently solitary thyroid nodule will be found to have a multinodular goitre. In the absence of marked asymmetry, rapid growth or an obvious ‘cold’ area on isotope imaging, multinodular goitre is, for practical purposes, a benign condition that may be associated with hyperthyroidism at presentation or in future years. On the other hand, a solitary palpable nodule may be malignant and the issue for the clinician is to identify the 5% that are malignant (usually papillary or follicular carcinomas) by using a combination of clinical assessment, imaging, thyroid function tests and cytology. Ultrasound-guided fine needle aspiration of impalpable thyroid nodules identified by imaging has demonstrated that malignancy is as common as in palpable solitary nodules. Although the natural history of these thyroid incidentalomas in an ageing population is not known, growth is likely to be slow and, in the UK at least, it is not common practice to adopt an aggressive policy of investigation and treatment.
