Thyroid nodule

A thyroid nodule is a distinct area of abnormal tissue within the thyroid gland. Nodules are very common - high-resolution ultrasound suggests that up to half of adults have at least one, most of which are tiny and cause no problems.

The vast majority of thyroid nodules are benign (non-cancerous). However, a small proportion - around 5 - 15% - are malignant, so any nodule that is felt or found incidentally should be assessed by a doctor.

Nodules may be solid or fluid-filled (cystic), and single or multiple. Most cause no symptoms. Larger nodules may be visible or felt as a lump in the neck, or occasionally cause mild pressure symptoms such as a sensation of something in the throat, difficulty swallowing, or hoarseness.

Assessment typically involves thyroid ultrasound and, if the nodule has features that warrant it, a fine needle aspiration (FNA) biopsy to examine cells under the microscope. Most benign nodules are simply monitored with periodic ultrasound.