Nodules in the thyroid gland are quite common, occurring in approximately 50% of persons by some estimates. The majority of these are benign growths within the gland. Any nodule has about a 5% probability of malignancy. Most of these will be a well differentiated thyroid carcinoma. Well differentiated thyroid cancer is either categorized as papillary thyroid carcinoma (or a variant), or as follicular thyroid carcinoma.
Several features are used to help distinguish those nodules which are benign and need no further intervention, from those that are concerning and an elevated probability of malignancy. A high-quality ultrasound (US) of the thyroid is essential to assess these nodules and stratify the risk. Features used in the stratification include nodule size, US echogenicity, nodule shape, interaction with surrounding tissue outside the thyroid gland, and calcifications.
For nodules which appear to be of elevated risk, a fine needle aspiration (FNA) under ultrasound guidance is recommended. This is a well tolerated procedure done in an office setting or radiology department. The cellular sample from an FNA needle is interpreted by a specialized pathologist (cytologist). It will be placed in one of six categories based on this interpretation: non-diagnostic, benign, follicular lesion of undetermined significance (FLUS), follicular neoplasm, suspicious for papillary carcinoma, or papillary carcinoma. The categorization is important for determining the next steps in management, which would either be observation with possible future US evaluation, observation with future repeat FNA biopsy, thyroid lobectomy, or total thyroidectomy.
Comments