Thyroid lobectomy for indeterminate FNA: not without consequences.

BACKGROUND: Thyroid nodules are exceedingly common, and the cytologic interpretation of fine needle aspiration (FNA) findings has been the reference standard for diagnosing nodules as benign, atypia or a follicular lesion of undetermined significance, suspicious for follicular or Hürthle cell neoplasm, suspicious for malignancy, or malignant. Many patients undergo thyroid lobectomy for indeterminate FNA findings (atypia or a follicular lesion of undetermined significance or suspicious for follicular or Hürthle cell neoplasm), although the risk of malignancy is low. The general data have quoted a 20% risk of hypothyroidism after lobectomy. The purpose of the present study was to determine the risk of hypothyroidism after lobectomy in our diverse population. METHODS: The pathology records from a large county hospital were reviewed to identify patients with indeterminate FNA findings. The incidence of hypothyroidism was determined by the need for thyroid hormone replacement therapy. Categorical variables were compared using the chi-square and continuous variables using the Mann-Whitney U test. RESULTS: A total of 655 FNAs were performed during the study period, and 60 resulted in indeterminate cases. Of these 60 patients, 17 subsequently underwent diagnostic lobectomy. The mean age was 52.8 ± 16.5 years, 88% were women, and 67% were Hispanic and 22% were African American. Only 6% had a final diagnosis of cancer, and eight patients (47%) became hypothyroid postoperatively. CONCLUSIONS: The incidence of hypothyroidism after diagnostic thyroid lobectomy in our patient population was much higher than previously reported. It is necessary to preoperatively counsel patients about this increased risk, in addition to the usual risks of nerve palsy and bleeding, with thyroid lobectomy. As testing of thyroid nodules evolves, the expense of preoperative testing should be weighed against the increased incidence for lifelong thyroid hormone replacement.

Identification of parathyroid tissue in thyroid fine-needle aspiration: A combined approach using cytology, immunohistochemical, and molecular methods.

OBJECTIVES: Parathyroid (PT) lesions can be difficult to recognize in thyroid fine needle aspirations (FNAs), and when not identified correctly, PT cells may be mistaken for potentially abnormal thyroid cells. We therefore studied the utility of combining cytology, immunohistochemistry, and a molecular classifier to identify PT cells in thyroid FNAs. METHODS: Thyroid FNAs were received in CytoLyt, and were evaluated initially using The Bethesda System for Reporting Thyroid Cytology (TBSRTC). The PT molecular classifier was performed along with the Afirma Gene Expression Classifier (GEC) on samples with indeterminate cytology. Immunohistochemistry (IHC) for PT was performed on all samples using Cellient cell block sections. Clinical and ultrasound information was collected, when available. RESULTS: PT tissue was identified in 60 thyroid FNAs. Forty-seven (47) samples had cytologic features that were suggestive of PT cells, and were subsequently confirmed with IHC. Thirteen (13) samples were not recognized as PT, and were considered to be either Bethesda III or IV indeterminate thyroid nodules; a PT gene expression signature was subsequently detected by the GEC. These samples were also confirmed as PT by IHC. Clinical and ultrasound features were suggestive of a PT lesion in only a third of cases. CONCLUSIONS: Cytologic features, coupled with IHC, can identify intrathyroidal PT cells in the majority of CytoLyt samples. However, a significant minority (22%) of these FNAs may be misclassified as indeterminate by TBSRTC criteria, and molecular detection of the PT tissue can be helpful to potentially avoid an additional biopsy or diagnostic surgery. Diagn. Cytopathol. 2017;45:526-532. © 2017 Wiley Periodicals, Inc.