Hürthle cell lesions of the thyroid: Progress made and challenges remaining

Abstract

Hürthle cell–predominant thyroid fine needle aspirations (FNA) are encountered frequently in routine practice, yet they are often challenging to diagnose accurately and are associated with significant interobserver variability. This is largely due to the ubiquity of Hürthle cells in thyroid pathology, ranging from nonneoplastic conditions to aggressive malignancies. Although limitations in cytomorphologic diagnoses likely will remain for the foreseeable future, our knowledge of the molecular pathogenesis of Hürthle cell neoplasia and application of molecular testing to cytologic material have increased dramatically within the past decade. This review provides context behind the challenges in diagnosis of Hürthle cell lesions and summarizes the more recent advances in diagnostic tools.

Impact of molecular testing on detecting mimics of oncocytic neoplasms in thyroid fine‐needle aspirates diagnosed as follicular neoplasm of Hürthle cell (oncocytic) type

“…Oncocytic metaplasia is a well-known nonneoplastic condition mimicking FNHCT. 2,4,25 On the other hand, approximately half of molecularly negative…”

“…1 Cellular thyroid fine-needle aspirates (FNAs) composed predominantly of oncocytic (Hürthle) cells, devoid of lymphocytes, and with scant colloid fall into an indeterminate diagnostic category and are diagnosed as follicular neoplasm, Hürthle cell (oncocytic) type (FNHCT), within the Bethesda System for Reporting Thyroid Cytopathology (BSRTC). 2,3 Distinguishing neoplastic from nonneoplastic oncocytic lesions on cytology may be challenging, whereas differentiating follicular oncocytic adenoma (FOA) from carcinoma is deferred to surgical pathology (with the risk of malignancy for thyroid nodules diagnosed as FNHCT ranging from 14% to 45%). 2 Importantly, medullary thyroid Subsets and Mimics of Oncocytic Neoplasms/Landau et al carcinoma, papillary thyroid carcinomas (PTC), intrathyroidal parathyroid nodules, oncocytic metaplasia of chronic lymphocytic thyroiditis (CLT) or nodular thyroid hyperplasia, and autonomously functioning thyroid nodules (AFTNs) may all present on preoperative cytology as FNHCT.…”

“…2,3 Distinguishing neoplastic from nonneoplastic oncocytic lesions on cytology may be challenging, whereas differentiating follicular oncocytic adenoma (FOA) from carcinoma is deferred to surgical pathology (with the risk of malignancy for thyroid nodules diagnosed as FNHCT ranging from 14% to 45%). 2 Importantly, medullary thyroid Subsets and Mimics of Oncocytic Neoplasms/Landau et al carcinoma, papillary thyroid carcinomas (PTC), intrathyroidal parathyroid nodules, oncocytic metaplasia of chronic lymphocytic thyroiditis (CLT) or nodular thyroid hyperplasia, and autonomously functioning thyroid nodules (AFTNs) may all present on preoperative cytology as FNHCT. 4 Over the last decade more was learned about molecular alterations of oncocytic follicular neoplasms and its oncocytoid mimics.…”

The dilemma of 18F-FDG PET/CT thyroid incidentaloma: what we should expect from FNA. A systematic review and meta-analysis

“…This study shows that FDG avid nodules show a relative excess of BETHESDA category IV and V FNA (see Table 4). Although the published studies included in this meta-analysis do not give specific information on the prevalence of Hurthle cell neoplasms, the finding of relatively higher frequencies of category IV and V FNA in thyroid TI implies that this is due to the underlying higher clinical ROM of PET avid thyroid nodules, in combination with a relative excess of HCN in nodules that are FDG avid which would typically fall in BETHESDA categories III and IV [14,[32][33][34].…”

Genetics, Diagnosis, and Management of Hürthle Cell Thyroid Neoplasms

“…Two studies reported recurrent RET-PTC translocations in HCCs using FISH and PCR methods ( 18 , 19 ). However, in larger cohorts using DNA-sequencing based methods, RET-PTC ( CCDC6-RET and NCOA4-RET ) translocations were not detected, nor were RET-PTC translocations recurrently identified in molecular testing of FNA specimens with Hürthle cell cytology ( 20 – 26 ).…”