BOSTON – according to the results of a retrospective, single-center study presented at the annual meeting of the American Association of Clinical Endocrinologists.
When nodules were located in the upper pole of the gland, the risk of malignancy was about 4 times higher than it was for nodules at other locations in the gland. Researchers confirmed the association using a multiple logistic regression model with adjustment for age, gender, body mass index, laterality, and number of nodules (odds ratio, 4.6; P = 0.03). The findings are believed to be the first to show an association between location of thyroid nodules on ultrasound and malignancy risk.
The results appear to elevate the value of ultrasound for predicting thyroid malignancy and should affect guidelines for ultrasound classification of thyroid nodules, researcher Fan Zhang, MD, PhD, a fellow at State University of New York, Brooklyn, said in a video interview. “In the future, I would recommend maybe we could consider including the location of thyroid nodules in the guidelines for better predictive value of malignancies,” she said.
Other ultrasound characteristics known to be associated with malignancy include findings of microcalcifications, increased vascularity, and nodules that are taller than they are wide, according to Dr. Zhang.
The retrospective review included data on 219 clinic patients with thyroid nodules who underwent fine-needle aspiration biopsy between July 2016 and June 2017. Nearly 80% of the nodules in the review were located in the lower pole of the gland, about 10% were in the upper pole, 7% were in the middle pole, and about 2% were found in the isthmus.
Fourteen nodules, or 7.4%, were found to be malignant, Dr. Zhang and her coauthors said in their presentation. Of those 14 malignancies, 7 were among the 149 nodules in the lower pole, 4 were among the 18 in the upper pole, and 3 were among the 21 in the middle pole.
The anatomy of the thyroid gland may be a factor in why upper pole nodules would be more likely to be associated with malignancy, according to Dr. Zhang. “The veins in the upper lobe are more tortuous compared to in the lower lobe,” she said, noting that slow venous drainage may increase the possibility of developing malignancy.
Dr. Zhang had no relevant disclosures to report.
SOURCE: Zhang F et al. AACE 2018, Abstract 1204.