A Retrospective Study of Clinicopathologic Outcomes of Nodules With Hürthle Cell Cytology and the Thyroid Nodule App (TNAPP) Ultrasound Recommendations.

OBJECTIVES

Hürthle cells are a common finding on thyroid fine-needle aspiration, but when they are the predominant cytology, they represent a difficult diagnostic challenge. The Thyroid Nodule App (TNAPP) is a new, publicly available web application utilizing ultrasound (US) features based on the updated 2016 American Association of Clinical Endocrinologists clinical practice guidelines for thyroid nodule management. This pilot study was performed to assess the TNAPP recommendations and surgical pathology outcomes of Hürthle cell-predominant thyroid nodules.

METHODS

A retrospective review of nodules with Bethesda III (atypia of undetermined significance with Hürthle cells) or Bethesda IV (suspicious for Hürthle cell neoplasm) cytology, for which surgery was performed between 2017 and 2021, was conducted. TNAPP US categories 1, 2, and 3 (low, intermediate, and high risk, respectively) were assigned based on nodule characteristics, and clinical management recommendations were recorded. Results were compared with histology-proven diagnoses.

RESULTS

Fifty-nine nodules in 57 patients where surgical pathology was available were analyzed with the TNAPP algorithm. Of the 59 nodules, 4 were US category 1 (low risk/suspicion), 40 were US category 2 (intermediate risk/suspicion), and 15 were US category 3 (high risk/suspicion). All US category 1 nodules were benign, while 30% of the US category 2 and 40% of the US category 3 nodules were malignant. Of the patients who had molecular marker testing with ThyroSeq, 22 out of 29 (76%) were positive, indicating either an intermediate or high risk of malignancy, 7 of which were malignant.

CONCLUSION

This preliminary study suggests that TNAPP is a useful clinical tool for sonographic assessment of thyroid nodules with Hürthle cell cytology.