[350] Application of the Bethesda Thyroid System in the Pediatric Population

Xiangbai Chen, Hedieh Honarpisheh, Liying Fu, Constantine Theoharis, David Chhieng, Diane Kowalski. Yale University, New Haven, CT

Background: Few studies have analyzed the Bethesda System for reporting pediatric thyroid nodules since the application of this system in 2007. Likewise, the usefulness of molecular testing in the pediatric age group has been reported in few studies. This study aims to evaluate the usefulness of the Bethesda System in pediatric thyroid nodules as well as the utility of molecular testing.
Design: All thyroid fine needle aspirations (FNAs) from patients 21 years of age or younger were collected from the pathology files of a tertiary referral hospital between the years 2008-2012. The cytologic diagnoses were reviewed and retrospectively correlated with molecular testing results and histologic results in cases with surgical follow-up. Nearly all FNAs were performed under ultrasound guidance.
Results: 234 FNAs from 225 patients were identified, accounting for 1.8% of all thyroid FNA evaluated during the study period. Among the 234 FNAs, 69(29%) cases had histologic follow up and 17 of 69 (25%) cases had BRAF analysis. The cohort included 183 (80%) females between 12 and 21 years of age (mean 17± 3.2) and 42 (20%) males between 4 and 21 years (mean 17± 3.1). Cytologic diagnoses were as follows: 156 (66.7%) cases benign, 10 (4.3%) cases AUS (atypia of of undetermined significance), 10 (4.3%) cases follicular neoplasm, 12 (5.1%) cases suspicious for malignancy, 35 (15.0%) cases malignant and 11 (4.7%) cases unsatisfactory. Of the 69 cases with histologic follow up, 23 (33%) cases were non neoplastic, 7 (10%) cases were benign neoplasms (adenoma), and 39 (56%) cases were malignant.

Cyto-Histology Correlation
 BenignAUSFNSuspiciousMalignant
Benign183110
FN30400
Malignant0 (0%)4 (57.1%)1 (16.7%)7 (87.5%)27 (100%)


Of the 17 cases sent for mutational analysis, 10 (59%) cases were positive for the BRAF mutation. All malignancies with the BRAF mutation were papillary thyroid carcinoma at final diagnosis. The sensitivity and specificity of diagnosing thyroid malignancy in this pediatric cohort is 100% and 94.7%, respectively.
Conclusions: Thyroid FNA is rarely encountered in the pediatric population; however, it is a highly sensitive and specific method for evaluating thyroid malignancy. There is a higher incidence of malignancy (15%) in children compared to adults (5.5%). The increased incidence of malignancy in this study may in part be due to a population bias, being drawn from a tertiary referral center. The prevalence of BRAF mutation in this cohort was similar to that in adults. This is in contrast to previous studies on pediatric thyroid nodules which reported a lower incidence of BRAF mutations in children.
Category: Cytopathology

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 94, Tuesday Afternoon

 

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