What Are Thyroid Nodules?
Thyroid nodules are commonly diagnosed. They are frequently found unexpectedly on routine physical examinations or imaging studies. They can present symptomatically as a visible lump in the neck, a pressure impairing swallowing, or, in rare cases, as a mass compressing the trachea and causing airway obstruction. Once discovered, evaluation typically centers on determining whether surgical excision will be required.
Symptoms and Types:
Nodules can be divided generally into benign (non-cancerous) and malignant (cancerous) types. Approximately 90% of nodules discovered turn out to be non-cancerous. Among benign nodules, colloid cysts, follicular adenomas, and nodules due to diffuse inflammatory conditions predominate. Malignant thyroid nodules are generally one of four types: papillary, follicular, medullary or anaplastic. Of these, the papillary and follicular types are by far the most common. Other, unusual types of nodules, include toxic hyperfunctioning nodules, and lymphomas.
Diagnosis and Tests:
Once discovered, a number of studies may be recommended in order to evaluate thyroid nodules, depending on the individual situation of the patient. A thyroid ultrasound is a common tool used to determine the exact size of the nodule, as well as other qualities, such as whether it is cystic or solid. A nuclear medicine thyroid scan may be used to determine whether the nodule is active in secreting thyroid hormone, which may provide clues about its potential for malignancy. Blood tests may be performed to determine the hormonal state of the gland, although these generally do not provide information regarding whether the nodule is malignant. Other imaging studies, such as CT scan or MRI scan may be recommended in special situations.
Fine Needle Biopsy: Frequently, a biopsy of the nodule using a fine needle through the skin is recommended to try to determine whether the tumor is malignant. If the nodule is easily felt, this can be done under local anesthetic in the office. If the nodule is more difficult to feel, biopsy of the nodule under ultrasound guidance by the radiologist may be required.
Biopsy Results: Needle biopsy results may reveal findings clearly indicating that the tumor is either benign or malignant, or the results may be inconclusive, and require interpretation along with other clinical findings to determine the risk for malignancy. Findings of colloid and cystic fluid are frequent findings suggesting benign conditions. Findings suggestive of papillary thyroid carcinoma are strong evidence of malignancy. However, findings of follicular cells can be difficult to interpret, since these are found both in benign tumors called follicular adenomas, and in malignant tumors called follicular carcinomas. Unfortunately, this can be a common predicament. Fine needle biopsies help physicians with their recommendations regarding the relative need for surgery, but they cannot absolutely determine whether a particular nodule is benign or malignant. Only surgical removal of the gland can demonstrate this definitively.
Treatment and Care:
Once the evaluation is complete, the physician assimilates these results, along with other factors, including the age of the patient, other significant health issues, and patient preferences to determine whether surgery (thyroidectomy) is recommended, or whether the nodule should be followed without surgery. If surgery is not recommended, follow-up ultrasounds or sometimes follow-up biopsies may be needed to ensure that the nodule does not show malignant features in the future.