Worth noting is that the most common suspicious feature found in this study’s cohort was hypoechoic solid nodules, which is a feature that has a sensitivity of 81% however a low specificity of 53% in detecting thyroid malignancy.5 This appearance also is found in 55% of benign thyroid nodules.6 The overlap of hypoechoic nodules as a feature in both benign and malignant thyroid nodules can present as a diagnostic challenge in differentiating between the two.
The 2015 ATA guideline recommends that low TSH warrants a radioiodine scan, and FNA should be considered for isofunctioning or nonfunctioning nodules with suspicious sonographic features. Hot nodules found on scintigraphy need no further cytologic evaluation because they are mostly benign.3 There is no clear stance on the use of ultrasound in hot nodules.
The answer to whether patients with hot nodules should undergo ultrasound still remains unclear. This study showed a surprising number of hot nodules with worrisome architecture found on ultrasound. However, whether that correlates to actual malignant findings remains unknown as most individuals in the cohort did not undergo biopsy. Also, given the high prevalence of suspicious findings, it may be difficult to use ultrasound as a diagnostic tool in patients with hot nodules as false positives may lead to unnecessary interventions such as biopsy.
Limitations
The patient population consisted mostly of men (84.3%) and cannot be applied to the general population. Thyroid nodules are 4 times more common in women than they are in men.7 Another limitation was the lack of data on patients’ radiation exposure while in military service or as civilians. Finally, as a retrospective study, there was unavoidable selection bias.
Conclusion
The prevalence of suspicious findings concerning for malignancy in hot nodules was 36.3% (16/44) based on the 2015 ATA guidelines. This study’s preliminary observation suggests that although ultrasound is a noninvasive and relatively inexpensive diagnostic modality, it has a limited role in the evaluation of hot nodules given the high prevalence of suspicious findings. Clinicians may still consider its use in patients who also have high-risk historic features. This was a thought-generating, retrospective study, and further prospective studies in larger populations are needed to validate the study’s results.
