Thyroid nodules are very common clinical problem. The increasing use of ultrasonography of the head and neck to image the thyroid, cervical nodes, or carotid arteries has resulted in an epidemic of nonpalpable thyroid nodules incidentally detected known as ultrasound-detected thyroid nodules. In addition, other imagings including computed tomography, magnetic resonance imaging and positron emission tomography scintigraphy have all resulted in detecting a significantly increasing number of thyroid nodules and they are collectively known as thyroid incidentalomas.

The overwhelming majority of these thyroid incidentalomas is benign in nature although a small proportion has been shown to be malignant with the majority being papillary thyroid carcinoma. Clinically occult papillary microcarcinomas based on tumour size of less than 1 cm are associated with excellent prognosis.

Thyroid nodules in general, and thyroid incidentalomas, in particular should be managed according to the established recommendations and guidelines prevailing the time of management. There should be a fine balance between the issues of unnecessary investigations resulting in additional cost and treatment-related side effects for majority of benign nodules and delay or missed diagnosis of small numbers of malignancy with the need of additional therapy as well as adverse outcome. Size of nodule was the major consideration in addition to clinical risk factors such as exposure to irradiation and family history of thyroid cancer in determining the need of needle biopsy. There has been increasing experience of applying ultrasound to provide information in selecting suspicious nodules for needle aspiration biopsy.

Needle biopsy is recommended for all palpable thyroid nodules. For incidentalomas, size and ultasonographic characteristics are important considerations for recommending biopsy.