Clinical utility of fine-needle aspiration cytology of the thyroid.

Fine-needle aspiration cytology (FNAC) of the thyroid has radically changed the management of patients with thyroid disease. It is an inexpensive, safe, and rapid procedure that usually gives a definitive morphological diagnosis. It frequently eliminates the need for diagnostic surgery. FNAC should be the initial diagnostic test to evaluate any palpable thyroid lesion. This direct approach reduces the need for other time-consuming and expensive investigations. FNAC can also determine whether patients with hyper- or hypothyroidism have underlying thyroiditis.