Malignancy Risks for Fine-Needle Aspiration of Thyroid Lesions According to The Bethesda System for Reporting Thyroid Cytopathology Vickie Y. Jo, M.D., Edward B. Stelow, M.D., Krisztina Z. Hanley, M.D. Department of Pathology, University of Virginia, Charlottesville, VA

Background Fine-needle aspiration is important for triaging patients with thyroid nodules

Background 30,000,000 patients with thyroid nodules > 1cm 30,000 malignancies <2,000 deaths due to thyroid cancer

Background No “universal” reporting schema Confusing terminologies 2007: “NCI Thyroid Fine-Needle Aspiration State of the Science Conference”

NCI Thyroid FNA “State of the Science” Six Committees (1) Indications and pre-FNA requirements (2) Training and credentialing for FNA (3) Technique (4) Reporting terminology and morphologic criteria (5) Ancillary studies (6) Post-FNA testing and treatment

NCI Thyroid FNA “State of the Science” Six Committees (1) Indications and pre-FNA requirements (2) Training and credentialing for FNA (3) Technique (4) Reporting terminology and morphologic criteria (5) Ancillary studies (6) Post-FNA testing and treatment

Bethesda Diagnostic Categories I. Nondiagnostic / Unsatisfactory II. Benign III. Atypia of Undetermined Significance / Follicular Neoplasm of Undetermined Significance IV. Suspicious for Follicular Neoplasm / Follicular Neoplasm V. Suspicious for Malignancy VI. Malignant

The Bethesda System for Reporting Thyroid Cytopathology Diagnostic Category Risk of Malignancy Usual Management Nondiagnostic Repeat FNA with u/s Benign 0-3% Clinical follow-up Atypical Follicular Lesion of Undetermined Significance 5-15% Repeat FNA Suspicious for Follicular Neoplasm 15-30% Surgical lobectomy Suspicious for Malignancy 60-75% Near-total thyroidectomy or surgical lobectomy Malignant 97-99% Near-total thyroidectomy

Aim of Study What is our institution’s experience with the proposed nomenclature?

Methods Reviewed all thyroid FNA diagnoses at the University of Virginia Recorded interpretations using new terminology Recorded follow-up cytology and histology

Methods: Examples BENIGN SUSPICIOUS FOR FOLLICULAR NEOPLASM Thyroid, Right Lobe, FNA: Abundant hemosiderin-laden macrophages, scant benign follicular cells, some colloid and rare Hürthle cells consistent with hemorrhagic cyst. BENIGN Thyroid, Right Lobe, FNA: Cellular follicular lesion. SUSPICIOUS FOR FOLLICULAR NEOPLASM

Methods “Cyst-fluid-only” was considered non-diagnostic “Atypical Follicular Lesion of Undetermined Significance” Aspirate considered adequate Diagnosis and/or note suggested the best course of action was re-aspiration

Methods Incidental papillary carcinomas were not considered malignant Malignant follow-up rate was calculated using only surgical resection cases Except Benign - calculation used total number of FNAs as the denominator

Methods We look at Romanowsky- and Papanicolaou-stained slides Occasionally Thin-Prep (usually cysts) We only use “rapid” interpretation with a fraction of cases

Results Bethesda Diagnosis No. Cases (%) Nondiagnostic 574 (19%) 3080 Thyroid FNAs Bethesda Diagnosis No. Cases (%) Nondiagnostic 574 (19%) Benign 1817 (59%) AFLUS 104 (3%) SFN 298 (10%) Suspicious for Malignancy 71 (2%) Malignant 216 (7%)

908 cases with follow-up surgical pathology Rates of Malignancy 908 cases with follow-up surgical pathology Bethesda Category Rate of Malignancy Reported Rates Nondiagnostic 13% Benign 1.6% 0-3% AFLUS 19% 5-15% SFN 25% 15-30% Suspicious for Malignancy 70% 60-75% Malignant 98% 97-99%

Results 126 ND cases were cyst-fluid-only 137 follow-up cytology cases for those originally interpreted as ND 64 (47%) of these remained ND

Conclusions At our institution, Bethesda classification of thyroid lesions yields similar results for risk of malignancy The associated risks of AFLUS, SFN, and suspicious for malignancy confirm the importance of these categories

Limitations Retrospective study We did not review aspirate slides but used a “best fit” philosophy Tertiary care center for thyroid malignancy

Thank You Edward B. Stelow, M.D. Krisztina Z. Hanley, M.D. Simone M. Dustin, M.D. James N. Lampros, M.D.