For nodules that are larger than one centimeter or nodules that have suspicious characteristics based on an ultrasound, a fine needle aspiration of the nodule is recommended.
A fine needle aspiration (FNA) biopsy is best carried out under ultrasound guidance. A small needle, generally smaller than those used for drawing blood, is placed directly into the nodule and multiple cells or fluid is withdrawn from the nodule. Specially trained pathologists interpret the tissue and determine whether the cells are benign, malignant or atypical. Ultrasound-guided FNA usually yields adequate specimens in 85 percent of individuals. For those 15 percent of individuals where the specimens are deemed inadequate, repeat aspiration is required. Newer molecular diagnostic tests can provide further information to clarify the diagnosis. Your endocrinologist will work closely with you and refer you to molecular diagnostic testing if needed.