title: A focal marked hypoechogenicity within an isoechoic thyroid nodule: is it a focal malignancy or not?
abstract: BACKGROUND
  A marked hypoechogenicity is a reliable criterion for a malignant nodule, whereas isoechogenicity is considered to be a benign ultrasonographic (US) finding. However, there have been no reports to demonstrate whether a focal marked hypoechogenicity within an isoechoic nodule is a focal malignancy.
  
  
  OBJECTIVE
  To evaluate whether a focal marked hypoechogenicity within an isoechoic nodule on US examination is a focal malignancy and to correlate US histologic findings using surgical or core needle biopsy (CNB) specimens.
  
  
  METHODS
  From January 2010 to August 2011, 28 consecutive patients (25 women, 3 men; mean age, 52.2 years) with 29 thyroid nodules, which showed a focal marked hypoechogenicity within an isoechoic nodule on US, underwent US-guided CNB for a suspicion of a focal malignancy. All nodules were confirmed by surgery (n = 6) or more than two consecutive US-guided biopsies (n = 23). We evaluated the risk of malignancy, and analyzed histological components which correlated with a focal marked hypoechogenic area within an isoechoic nodule on US. Statistical analysis was performed using the Mann-Whitney U test and Fisher's exact test.
  
  
  RESULTS
  Of the 29 nodules, 25 were benign (86.2%) and four were malignant (13.8%). The peripheral location of focal marked hypoechogenicity within an isoechoic nodule was the only significant US finding that suggested malignancy (P = 0.03). All benign focal marked hypoechogenicities were histologically composed of severe fibrosis with a few follicular cells with varying frequencies of hemosiderin, calcification, infarction, and granulation tissue.
  
  
  CONCLUSIONS
  Although a focal marked hypoechogenicity within an isoechoic nodule is usually benign, the peripheral location of a focal marked hypoechogenicity may be a malignancy. The histologic information obtained by CNB specimen may reduce the needs for repetitive fine needle aspirations or diagnostic surgery.
authors.affiliation: Department of Radiology and the Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea Department of Radiology, Ajou University School of Medicine, Suwon, Republic of Korea.
authors.forename: Eun Ju
authors.initials: EJ
authors.lastname: Ha
authors.affiliation: Department of Radiology and the Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Jung Hwan
authors.initials: JH
authors.lastname: Baek
authors.affiliation: Department of Radiology and the Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea radbaek@naver.com.
authors.forename: Jeong Hyun
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Radiology and the Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Ha Young
authors.initials: HY
authors.lastname: Lee
authors.affiliation: Department of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Dong Eun
authors.initials: DE
authors.lastname: Song
authors.affiliation: Department of Radiology, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
authors.forename: Jae Kyun
authors.initials: JK
authors.lastname: Kim
authors.affiliation: Department of Endocrinology and Metabolism, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Young Kee
authors.initials: YK
authors.lastname: Shong
authors.affiliation: Department of Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Suck Joon
authors.initials: SJ
authors.lastname: Hong
mesh_terms: D000328:Adult; D000368:Aged; D062005:Biopsy, Large-Core Needle; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012189:Retrospective Studies; D013959:Thyroid Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000473:pathology; D014463:Ultrasonography
keywords: Thyroid cancer; core needle biopsy; fine needle aspiration; thyroid nodule; ultrasound