Objectives: To review our institutional experience and to analyze the clinical decisions made after a cytological diagnosis of atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS). Study Design: This is a retrospective review of all thyroid fine-needle aspiration (FNA) cytologies performed in the Hospital Clínico San Carlos (Madrid) between 2010 and 2014. Results: One hundred thirty thyroid FNA were categorized as AUS/FLUS (5%). One hundred six (81.5%) patients were women, and the mean age was 59 years. In 61 patients a repeated FNA was performed (46%). Fifty-five nodules were treated surgically (42.3%), with a histopathological diagnosis of nodular hyperplasia in 36 cases (65%), adenoma in 11 (20%), and carcinoma in 8 (14.5%). In the group of nonsurgical patients (n = 75), a repeated FNA was performed in 43 (57.3%) cases. We found no statistically significant association between sex or age and clinical management (p = 0.13 and p = 0.31, respectively). Conclusions: Clinical management after an AUS/FLUS FNA diagnosis is erratic and does not match standardized management protocols. The AUS/FLUS classification has not led to new diagnostic tests in a relevant percentage of patients. The implementation of consensual institutional strategies could lead to better management of these cases.

Hegedüs L: Clinical practice: the thyroid nodule. N Engl J Med 2004;351:1764-1771.
Frates MC, Benson CB, Charboneau JW, Cibas ES, Clark OH, Coleman BG, et al: Management of thyroid nodules detected at US: Society of Radiologists in Ultrasound Consensus Conference Statement. Radiology 2005;237:794-800.
Gharib H, Papini E, Paschke R, Duick DS, Valcavi R, Hegedüs L, et al: AACE/AME/ETA thyroid nodule guidelines. Endocr Pract 2010;16(suppl 1):3.
Wu HH, Jones JN, Osman J: Fine-needle aspiration cytology of the thyroid: ten year experience in a community teaching hospital. Diagn Cytopathol 2006;34:93-96.
Ali SZ, Cibas ES: The Bethesda System for Reporting Thyroid Cytopathology: Definitions, Criteria and Explanatory Notes. New York, Springer, 2010.
Layfield LJ, Cibas ES, Baloch Z: Thyroid fine needle aspiration cytology: a review of the National Cancer Institute state of the science symposium. Cytopathology 2010;21:75-85.
VanderLaan PA, Marqusee E, Krane JF: Clinical outcome for atypia of undetermined significance in thyroid fine-needle aspirations: should repeated FNA be the preferred initial approach? Am J Clin Pathol 2011;135:770-775.
Krane JK, Vanderlaan PA, Faquin WC, Renshaw AA: The atypia of undetermined significance/follicular lesion of undetermined significance malignant ratio: a proposed performance measure for reporting in the Bethesda system for thyroid cytopathology. Cancer Cytopathol 2012;120:111-116.
Dincer N, Balci S, Yazgan A, Guney G Ersoy R, Cakir B, et al: Follow-up of atypia and follicular lesions of undetermined significance in thyroid fine-needle aspiration cytology. Cytopathology 2013;24:385-390.
Chaves S, Fernandez-Aceñero MJ, Cazorla A, Cedeño M, Fortes J, Gavín E, et al: Implementation of a joint protocol for the management of thyroid nodules with a cytological diagnosis of follicular lesion of undetermined significance: experience in one hospital. Cytopathology 2013;24:81-84.
Faquin WC, Baloch ZW: Fine-needle aspiration of follicular patterned lesions of the thyroid: diagnosis, management, and follow-up according to National Cancer Institute (NCI) recommendations. Diagn Cytopathol 2010;38:731-739.
Haugen BR, Alexander EK, Bible KC, Doherty GM, Mandel SJ, Nikiforov YE, et al: 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer. Thyroid 2016;26:1-133.
Rabaglia JL, Kabbani W, Wallace L, Holt S, Watumull L, Pruitt J, et al: Effect of the Bethesda system for reporting thyroid cytopathology on thyroidectomy rates and malignancy risk in cytologically indeterminate lesions. Surgery 2010;148:1267-1272, discussion 1272-1273.
Walts AF, Bose S, Fan X, Frishberg D, Scharre K, de Peralta-Venturina M, et al: A simplified Bethesda system for reporting thyroid cytopathology using only four categories improves intra- and inter observer diagnostic agreement and provides non-overlapping estimates of malignancy risks. Diagn Cytopathol 2012;40(suppl 1):E62-E68.
Cibas ES, Baloch ZW, Fellegara G, LiVolsi VA, Raab SS, Rosai J, et al: A prospective assessment defining the limitations of thyroid nodule pathologic evaluation. Ann Intern Med 2013;159:325-332.
Iskandar ME, Bonomo G, Avadhani V, Persky M, Lucido D, Wang B, et al: Evidence for overestimation of the prevalence of malignancy in indeterminate thyroid nodules classified as Bethesda category III. Surgery 2015;157:510-517.
Nagarkatti SS, FaquinWc, Lubitz CC, García DM, Barbesino G, Ross DS, et al: Management of thyroid nodules with atypical cytology on fine-needle aspiration biopsy. Ann Surg Oncol 2013;20:60-65.
Ho AS, Sarti EE, Jain KS, Wang H, Nixon IJ, Shaha AR, et al: Malignancy rate in thyroid nodules classified as Bethesda category III (AUS/FLUS). Thyroid 2014;24:832-839.
Chen JC, Pace SC, Chen BA, Khiyami A, McHenry CR: Yield of repeat fine-needle aspiration biopsy and rate of malignancy in patients with atypia or follicular lesion of undetermined significance: the impact of the Bethesda system for reporting thyroid cytopathology. Surgery 2012;152:1037-1044.
Layfield LJ, Morton MJ, Cramer HM, Hirschowitz S: Implications of the proposed thyroid fine-needle aspiration category of ‘‘follicular lesion of undetermined significance'': a five-year multi-institutional analysis. Diagn Cytopathol 2009;37:710-714.
Broome JT, Cate F, Solorzano CC: Utilization and impact of repeat biopsy for follicular lesion/atypia of undetermined significance. World J Surg 2014;38:628-633.
Jo VY, Stelow EB, Dustin SM, Hanley KZ: Malignancy risk for fine needle aspiration of thyroid lesions according to the Bethesda system for reporting thyroid cytopathology. Am J Clin Pathol 2010;134:450-456.
Nayar R, Ivanovich M: The indeterminate thyroid fine-needle aspiration: experience from an academic center using terminology similar to that proposed in the 2007 National Cancer Institute Thyroid Fine Needle Aspiration State of the Science Conference. Cancer 2009;117:195-202.
McElroy MK, Mahooti S, Hasteh F: A single institution experience with the new Bethesda system for reporting thyroid cytopathology correlation with existing cytologic, clinical, and histological data. Diagn Cytopathol 2014;42:564-569.
Sullivan PS, Hirschowitz SL, Fung PC, Apple SK: The impact of atypia/follicular lesion of undetermined significance and repeat fine-needle aspiration: 5 years before and after implementation of the Bethesda system. Cancer Cytopathol 2014;122:866-872.
Ryu YJ, Jung YS, Yoon HC, Hwang MJ, Shin SH, Cho JS, et al: Atypia of undetermined significance on thyroid fine needle aspiration: surgical outcome and risk factors for malignancy. Ann Surg Treat Res 2014;86:109-114.
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