Abstract
Background: Thyroid nodules are very common in adults. One percent of men and 5% of women have nodules on exam, and 19-68% of adults have thyroid nodules on ultrasound. Majority (85-90%) of them are benign. Most concerning is the diagnosis of thyroid cancer. These nodules can be stratified into risk groups based on ultrasonographical criteria. There are 5 internationally endorsed sonographic classification systems (ATA, ACR, European Thyroid Association and Korean Society of Thyroid Radiology). After classification, decision to perform FNA biopsy is made based on size of the nodules. Some of the other parameters that have been considered to increase risk of cancer are BMI, TSH level, radiation exposure to the neck before puberty and family history of thyroid cancer. Cytogenetic testing of the FNA specimen may also help determine the need for excision. Study Design: We retrospectively studied a group of veterans referred for endocrine consultation for thyroid nodules that had undergone FNA based on ACR and ATA ultrasonographical classification (total of 127 nodules). On reviewing these charts over the past 4 years, we noted that approximately 39% (49/127) of the nodules were <2cm, 35% (44/127) were 2-4cm and 26% (34/127) were >4cm in size. We examined patient demographics and characteristics of nodules >4cm, since it is frequently a dilemma whether to clinical monitor these nodules or refer them for surgical excision. Results: Seventeen percent of patients were females. Majority were between 60-65 years of age, had a BMI 30-35 and TSH of <2. Based on review of ultrasound images and ACR and ATA classification, 55% of the nodules (19/24) had a score of 4-6 points on the TIRAD’s scale and based on ATA classification, 52% (18/34) were in the high-risk category. The ultrasound-guided FNA results showed that 65% were benign-Bethesda II (22/34), 12% were Bethesda III (4/34) and IV, 3% Bethesda V (1/34) and 15% Bethesda I (5/34). Eighteen percent of the nodules were referred for surgical excision (6/34); 3% were malignant (1/34), and the rest were benign (27/34). Discussion: It is unclear if the risk of thyroid cancer in nodules >4cm is any different from that of smaller nodules and if there should be different criteria used in nodules >4cm for risk stratification. Other questions to address are how these nodules should be monitored for growth and what criteria should be used to determine need for surgical intervention, other than FNA results or compression symptoms. Recent studies looking at growth of thyroid nodules over time do not indicate clear predictors for malignancy. Further studies are needed.