PAX8 is expressed in anaplastic thyroid carcinoma diagnosed by fine-needle aspiration: a study of three cases with histological correlates

Abstract

Objective: It is difficult to diagnose anaplastic thyroid carcinoma (ATC) in a fine-needle aspiration (FNA) sample because, given the loss of morphological and immunophenotypical follicular thyroid features, its cytology resembles that of other undifferentiated neoplasms. Recent studies have shown that immunostaining for paired box gene 8 (PAX8), a transcription factor expressed in normal thyroid, is effective for diagnosing ATCs on histology. The aim of this study was to evaluate whether PAX8 could be used to identify ATCs on cytology also. Design and methods: We selected three PAX8-immunostained undifferentiated FNA samples previously diagnosed as suspected ATCs, whose cell block had been negative for the expression of TGB and thyroid transcription factor-1. Matched histological samples, available in two cases, were also processed for PAX8 immunohistochemistry. Results: All three FNA samples were PAX8 positive. Two samples that had an epithelioid pattern showed a diffuse, intense nuclear signal. The third sample, which had a spindle-cell pattern, showed less intense and more patchy staining. Matched histology yielded overlapping results. Conclusions: PAX8 immunocytochemistry can help cytopathologists to diagnose ATCs.

The role of thyroid fine‐needle aspiration cytology in the pediatric population: An institutional experience

“…With regard to the morphological features, to the best of our knowledge these markers have been studied only rarely in the childhood population both as single markers or immunopanels. Recently, apart from the main worldwide classic markers, a new promising and helpful marker with high sensitivity and specificity appears to be paired box gene 8 (PAX8) as underlined by Schmitt et al in applying it to malignant thyroid cytology (especially PTC), even though these findings need to be supported by larger series that include young patients . Taking these recommendations and our previous experience with the application of an immunopanel comprised of HBME‐1 and galectin‐3 together, in the current study we studied all our pediatric cases diagnosed as FN/AUS, SM, and PM with this latter immunopanel .…”

Cytologic features of aggressive variants of follicular‐derived thyroid carcinoma

“…The majority of cases are fatal, often between 6 months and 1 year after presentation, with a median 1‐year survival rate of only 10% to 20%. The typical clinical appearance is that of an older patient with a rapidly enlarging firm and fixed infiltrative anterior neck mass . These tumors may be associated with pain, dyspnea, hoarseness, dysphagia, and vocal cord paralysis.…”

The Bethesda System for Reporting Thyroid Cytopathology: Proposed Modifications and Updates for the Second Edition from an International Panel

“…PAX-8 is a helpful immunocytochemical stain [48,49,50], since it is usually retained in UTC, while TTF-1 can rarely be focal and variably positive, and thyroglobulin is always negative. Some advances have been made in the molecular characterization of UTC, including high rates of MAPK pathway genes mutations, p53 mutations, and TERT -promoter mutations.…”