ORIGINAL ARTICLE Are cytologic and histopathologic features of hot thyroid nodules different from cold thyroid nodules? Husniye Baser MD 1 | Oya Topaloglu MD 1 | Muhammet C. Bilginer MD 1 | Serap Ulusoy MD 2 | Aydan Kılıcarslan MD 3 | Elif Ozdemir MD 4 | Reyhan Ersoy MD 1 | Bekir Cakir MD 1 1 Department of Endocrinology and Metabolism, Yildirim Beyazit University Faculty of Medicine, Ankara, Turkey 2 Department of General Surgery, Yildirim Beyazit University Faculty of Medicine, Ankara, Turkey 3 Department of Pathology, Yildirim Beyazit University Faculty of Medicine, Ankara, Turkey 4 Department of Nuclear Medicine, Yildirim Beyazit University Faculty of Medicine, Ankara, Turkey Correspondence Husniye Baser, Ovecler, 1297 Sokak, No: 1/22, 06460 Ankara, Turkey. Email: drhusniyebaser@yahoo.com.tr Abstract Background: We aimed to compare the cytology and histopathology results of hot, cold, and warm nodules in patients who had thyroidectomy due to toxic multinodular goiter (TMNG). Methods: Five hundred and nine thyroid nodules from 413 patients who had opera- tion with TMNG were included in this retrospective study. The nodules were catego- rized as hot, cold, and warm groups. The cytology and histopathology results were compared. Results: The 509 thyroid nodules were grouped as hot (n = 364 [71.5%]), cold (n = 122 [24.0%]), and warm (n = 23 [4.5%]) according to scintigraphy. Cytological evaluations of 364 hot nodules were as follows: 80 (22%) nondiagnostic (ND), 259 (71.2%) benign, 17 (3.6%) atypia of undetermined significance/follicular lesion of undetermined significance (AUS/ FLUS), 2 (0.5%) follicular neoplasm/suspicious for follicular neoplasm (FN/SFN), 2 (0.5%) suspicious for malignancy (SM), and 4 (1.1%) malignant. The cytology of 122 cold nodules were ND in 25 (20.5%), benign in 86 (70.5%), AUS/FLUS in 8 (6.6%), FN/SFN in 1 (0.8%), and finally SM in 2 (1.6%). The 23 warm nodules were determined as ND, benign, and FN/SFN in 7 (30.4%), 15 (65.2%) and 1 (4.3%), respectively. There were no differences according to cyto- logical results between groups (P = .616). However, malignancy rate was 3.8% in hot nodules, it was found as 6.6% in cold nod- ules. The malignancy was detected in 4.3% of warm nodules. There were no differ- ences in malignancy rates between groups (P = .459). Conclusion: We demonstrated similar malignancy rates in hot nodules when com- pared with cold and warm nodules. KEYWORDS cold nodule, cytology, histopathology, hot nodule, warm nodule 1 | INTRODUCTION In the past, hyperthyroidism was thought to be protective against thyroid cancer and some authors reported that hyperthyroidism and malignancy rarely occur simultaneously. 1,2 However, many recent studies demonstrate that detection of a thyroid cancer incidentally among patients operated for a benign toxic thyroid disease is not rare. The incidence of thyroid malignancy was reported to be 0%-16.6% in patients with Graves' disease Received: 6 March 2019 Revised: 5 May 2019 Accepted: 28 May 2019 DOI: 10.1002/dc.24251 Diagnostic Cytopathology. 2019;1–6. wileyonlinelibrary.com/journal/dc © 2019 Wiley Periodicals, Inc. 1