Table 3 Rates of Malignancy by Category

Number of cases(% of total FNAs)

Patients withfollowup(% of cases)

Patients withmalignancy(% of cases)

AUS 313 (7%) 235 (75%) 38 (12%)

Abstracts S47

104

Understanding the Management and Clinical Follow-up of “Atypia ofUndetermined Significance/Follicular Lesion of UndeterminedSignificance” (AUS/FLUS) Category in Thyroid FNA: A RetrospectiveStudy in a Tertiary Care Center

Israh Akhtar, MD, Xuehui Liu, MD, Ric Bowlin, SCT(ASCP),Rhyne Flowers, MD, Mithra Baliga, MDUniversity of Mississippi Medical Center, Jackson, Mississippi

Introduction: The Bethesda System for Reporting Thyroid Cytopathology(BSRTC) was developed to standardize reporting of thyroid fine needleaspiration biopsy (FNAB) results to better triage patients and improveclinical communication and management. According to this classification,the “Atypia of undetermined significance/Follicular lesion of undeterminedsignificance” (AUS/FLUS) is a heterogenous category that includes caseswith ambiguous cytological findings in which the cytomorphologicalfeatures are not convincingly benign, yet not atypical enough to interpretas “suspicious or positive for malignancy”. This study aims to determinethe rate of this category in our institute and to evaluate the clinical outcomeof these patients.Materials and Methods: A retrospective review of thyroid FNAB’s wasconducted from April 2010, when the BSRTC was implemented in ourlaboratory, until April 2013. Cytologic categories included non-diagnostic,benign, AUS/FLUS, suspicious for neoplasm, and positive for malignancy.The follow up of the diagnostic category “AUS/FLUS” was evaluated.Results: A total of 676 thyroid FNABs were retrieved from cytology database during this study period. There were 56 non-diagnostic cases, 541benign diagnoses, 27 belonged to AUS/FLUS category, 28 Follicular

CEPTC 87 (2%) 78 (90%) 54 (62%)SPTC 68 (1.5%) 63 (92%) 59 (87%)

Table 1 Follow-up of AUS/FLUS diagnostic category

Total Cases with AUS/FLUS Dx 27Cases with no follow up 13 (48.1%)Cases with follow-up 14 (51.8%)Follow-up of 14 casesCase 1 Thyroidectomy done in One month, Dx

Adenomatous nodulesCase 2 Thyroidectomy done in One month, Dx

Follicular carcinomaCase 3 Thyroidectomy done in One month, Dx

Adenomatous nodulesCase 4 Thyroidectomy done in Three months, Dx

Multinodular GoiterCase 5 Repeat FNA in three month, Dx BFNCase 6 Repeat FNA in one month, Dx Benign,

Followed by thyroidectomy in two months,Dx Minimally invasive Follicular carcinoma

Case 7 Thyroidectomy done in One month, DxFollicular variant of papillary carcinoma

Case 8 Thyroidectomy in three months, DxFollicular variant of papillary carcinoma

Case 9 Thyroidectomy done in Four months, DxFollicular variant of papillary carcinoma

Case 10 Thyroidectomy done in One month, DxFollicular variant of papillary carcinoma

Case 11 Thyroidectomy done in One month, DxPapillary microcarcinoma

Case 12 Thyroidectomy done in One month, DxAdenomatous Goiter

Case 13 Repeat FNA in one year, Dx Suspicious forFollicular neoplasm, No follow-up

Case 14 Thyroidectomy in six months, DxInsular carcinoma

neoplasm or suspicious for malignancy and 24 positive for malignancy. Thecategory of AUS/FLUS was followed up and the clinical managementobserved. (See Table 1)Conclusion: The rate of AUS/FLUS category in our laboratory is 3.99%.This is relatively lower than the recommended 7% threshold for thisinterpretation. From the data collected, only one patient had repeat FNAafter 3 months, which is the appropriate recommendation for this categoryaccording to the guidelines. However, 8 of 14 cases (57.1%) with follow-upthyroidectomies had malignancy, papillary thyroid carcinoma being mostcommon. Also, with continued follow-up, the rates of malignancy in theother patients may even increase. Therefore, clinical management should betailored individually, based on pertinent clinical and imaging findings.

105

An Audit of Atypical Thyroid FNA Using The Bethesda System forReporting Thyroid Cytology (TBSRTC) in Regional NSW, Australia

Christine Loo, BMedSc, MBBS, PhD1,Andreas K. Breitbarth, B Psych (Hons)2,Alistair G. Lochhead, MBBS, FRCPA, FIAC1

1Southern IML Pathology, Wollongong, Australia; 2University ofWollongong, Wollongong, Australia

Introduction: The Bethesda System for Reporting Thyroid Cytology(TBSRTC) was introduced to promote standardisation of thyroid FNAreporting among different laboratories. This was formally adopted in ourpractice in early 2011.Materials and Methods: We have conducted an audit of thyroid FNAreports from May 2011 to August 2012, with follow up (FNA andhistology) to June 2013. Category 3 (atypical) appears to be the mostcontroversial of the diagnostic categories of TBSRTC and we wish to reportour experience with this group. Our practice provides the majority ofcytology and histology services in the Illawarra /Shoalhaven regions ofNSW so that our results are probably representative of this population.Results: Over the study period, we reported 776 thyroid FNA biopsies ofwhich 30 were classified as “atypia of uncertain significance” (category 3,TBSRTC). Thirteen of these cases showed paucicellular smears with someatypical features. The others were at least moderately cellular but showedminimal colloid, predominance of oncocytic features, some featuressuggestive (but not diagnostic) for papillary thyroid carcinoma or areas ofmicrofollicular pattern, insufficient for classification in categories 4(suspicious for follicular neoplasm) or 5 (suspicious of malignancy). Followup was obtained for 18 cases. Histology showed 1 case of MALTlymphoma, 6 cases with papillary thyroid carcinoma, 3 follicular adenomas,1 medullary thyroid carcinoma and 1 case of follicular carcinoma(minimally invasive). Repeat FNA was done for 8 cases and showeda benign pattern (TBSRTC category 2) in 6 cases and possible follicularlesion (TBSRTC category 4) in 2 cases. However, subsequent surgeryrevealed that 2 cases with benign results on repeat FNA showed MALTlymphoma and papillary thyroid carcinoma.Conclusion: Review of the cases showed that the atypical smears showedfeatures predictive of the final diagnosis in most instances of papillarythyroid carcinoma, but less for follicular lesions.

106

Interobserver Agreement in Assessment of Architectural Atypia inThyroid Fine Needle Aspirates

Abha Goyal, MD, Charles V. Biscotti, MD, Li Yan Khor, MB BCh,Deborah J. Chute, MDCleveland Clinic, Cleveland, Ohio

Introduction: There is a lack of interobserver agreement in classifiyingthyroid fine needle aspirates (FNAs) with architectural atypia as benign orAUS(atypia of undetermined significance) or suspicious for follicular neoplasm(SFN) based on the current Bethesda system criteria. We assessed theinterobserver agreement at our institution in diagnosing such thyroid FNAs.