title: Malignant-looking thyroid nodules with size reduction: core needle biopsy results.
abstract: OBJECTIVE
  The aim of this study was to evaluate whether malignant-looking thyroid nodules with size reduction were malignant or not.
  
  
  METHODS
  From November 2010 to July 2011, we retrospectively enrolled 16 patients with 16 nodules (11 females and five males; mean age, 55 years) who underwent core needle biopsy (CNB), and whose thyroid nodules had malignant ultrasonographic (US) features, although they showed size reduction (>20% decrease in maximum diameter) during the follow-up period (mean, 37±27 months). The histologic findings of the CNB specimen were reviewed and correlated with the US findings. US studies were analyzed for their internal content, shape, margin, echogenicity, the presence of microcalcification and macrocalcification, inner isoechoic rim, and low-echoic halo.
  
  
  RESULTS
  All nodules were confirmed as benign by CNB. Pathologic analysis was available for 12 CNB specimens. US imaging showed central hypoechogenicity or marked hypoechogenicity in all cases and a peripheral isoechoic rim in 15 nodules. US-pathologic correlation showed that the central hypoechoic area was primarily composed of fibrosis (12/12) and hemorrhage (8/12) and that the isoechoic rim was composed of follicular cells.
  
  
  CONCLUSIONS
  In our study, the CNB results of all of the malignant-looking thyroid nodules with size reduction were benign and were primarily composed of internal fibrosis and hemorrhage. Understanding these US and pathologic features could prevent repeated fine-needle aspiration or unnecessary diagnostic surgery.
authors.affiliation: Department of Radiology and the Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.|Department of Radiology, Inha University School of Medicine, Incheon, Korea.
authors.forename: Ha Young
authors.identifier: 0000-0003-2343-3434
authors.initials: HY
authors.lastname: Lee
authors.affiliation: Department of Radiology and the Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jung Hwan
authors.identifier: 0000-0003-0480-4754
authors.initials: JH
authors.lastname: Baek
authors.affiliation: Department of Radiology and the Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.|Department of Radiology, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Eun Ju
authors.identifier: 0000-0002-1234-2919
authors.initials: EJ
authors.lastname: Ha
authors.affiliation: Department of Radiology and the Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.|Department of Health Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jee Won
authors.identifier: 0000-0002-7194-2826
authors.initials: JW
authors.lastname: Park
authors.affiliation: Department of Radiology and the Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jeong Hyun
authors.identifier: 0000-0002-0021-4477
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Dong Eun
authors.identifier: 0000-0002-9583-9794
authors.initials: DE
authors.lastname: Song
authors.affiliation: Department of Endocrinology and Metabolism, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Young Kee
authors.initials: YK
authors.lastname: Shong
keywords: Biopsy, fine-needle; Biopsy, large-core needle; Thyroid nodule; Ultrasonography