Thyroid nodules are common, with palpable nodules found in 4% to 7% of the adult US population and solitary or multiple nodules found at much higher rates during ultrasonographic screening.
"Most of these nodules — about 95% — are entirely benign," says Hossein Gharib, M.D., of the Division of Endocrinology, Diabetes, Metabolism, and Nutrition at Mayo Clinic. "Identifying the occasional thyroid cancer, however, requires careful evaluation of every nodule we find, using a combination of clinical assessment, neck palpation, ultrasound imaging, and, in many cases, analysis of a biopsy specimen."
Sometimes, thyroid nodules are noticed by the patient or a family member or are discovered during a routine physical examination. They rarely cause symptoms, unless they are large enough to interfere with swallowing. Thyroid cancer can invade and damage the recurrent laryngeal nerve, causing hoarseness. Such invasion and damage, however, are infrequent.
"Most nodules are incidental discoveries," notes Diana S. Dean, M.D., of the Division of Endocrinology, Diabetes, Metabolism, and Nutrition at Mayo Clinic, "and now many more such nodules are discovered because of the increased use of imaging performed for other reasons, including carotid ultrasonography, neck or chest computed tomography, magnetic resonance imaging, and even positron emission tomography."
"Diagnosing a thyroid nodule accurately and promptly is important," says Melanie L. Richards, M.D., of the Department of Surgery at Mayo Clinic, "because early diagnosis improves the likelihood that a cancer can be discovered while still contained within the thyroid gland and amenable to surgery. Once soft tissue invasion has occurred or lymph nodes are extensively involved, the chance of surgical cure drops substantially and there is a much higher incidence of metastatic spread of these late-stage cancers."
Prompt diagnosis is also important for the patient because the finding of a nodule often raises fears about cancer and a delay to diagnosis fuels the concern and anxiety.
Bryan McIver, M.B., Ch.B., Ph.D., of the Division of Endocrinology, Diabetes, Metabolism, and Nutrition at Mayo Clinic, says: "The most recent set of guidelines from the American Thyroid Association, published last year, specifies that the evaluation of a thyroid nodule should include:
"Not every nodule needs to be biopsied, so the clinical scenario and ultrasound features are important in selecting the appropriate nodule for biopsy."
Typically, these steps involve several appointments for the patient and often take a number of days. "Given the small number of steps involved," says Dr. McIver, "it seemed sensible to develop a coordinated approach to meet the needs of these patients so that their entire assessment could be provided at a single visit to the clinic. To streamline the evaluation, we created the Thyroid Nodule Clinic, at which patients with thyroid nodules can have their assessment completed at a single visit."
Opened in July 2009, the Thyroid Nodule Clinic provides a
1-stop thyroid nodule evaluation that includes a focused clinical assessment, ultrasound evaluation, and FNA — all typically performed within a 60-minute appointment.
"The ultrasound allows us to select both palpable and impalpable nodules for biopsy and target the most suspicious nodule, which is not always the largest nodule," says Dr. Dean. "Using ultrasound guidance for those biopsies, we have improved our diagnostic yield dramatically. We perform more than 600 biopsies per year in this way and can now expect a clear diagnosis in more that 95% of cases at the first attempt."
Furthermore, because of the coordinated assessment provided through the Thyroid Nodule Clinic, FNA results are typically available within 2 hours, so the patient usually receives a definitive result of the entire assessment within
Dr. McIver says: "For most patients referred with a thyroid nodule, the Thyroid Nodule Clinic provides coordinated care, a thorough assessment, and a definitive result, all in the space of a morning. Patients with a benign nodule can be reassured, and those with a malignant or suspicious nodule can be offered an appropriate surgical referral, often within 24 hours.
"We believe that the Thyroid Nodule Clinic improves our care of these patients while lowering costs, improving efficiency, and providing a better service to the referring physician."