title: Sonographic and Clinical Features of Papillary Thyroid Microcarcinoma Less than or Equal to Five Millimeters: A Retrospective Study.
abstract: OBJECTIVE
  To retrospectively compare the sonographic and clinical features of papillary thyroid microcarcinoma (PTMC) ≤5 mm and PTMC >5 mm to improve the diagnostic value of ultrasonography.
  
  
  METHODS
  A total of 367 cases of PTMC between January 2013 and December 2014 was included in this study. The patients were classified into group A (≤5 mm, n = 181) or group B (>5 mm, n = 186), and the sonographic and clinical features were reviewed and compared between the two groups.
  
  
  RESULTS
  There was no significant difference in the shape, ratio of length/width, boundary, peripheral halo ring, echogenicity, cystic change and accompanying Hashimoto's thyroiditis between these two groups. However, the calcification (61.3% vs. 72.6%) and hypervascularity (13.8% vs. 24.7%) were more frequent in group B (p = 0.026 and 0.008, respectively). The patients were younger, and more patients were aged less than 45 years (41.4% vs. 57.0%) in group B. Capsular invasion (7.2% vs. 34.4%), multifocality (21.5% vs. 48.9%), bilaterality (17.1% vs. 39.8%), central lymph node metastasis (13.8% vs. 38.2%) and lateral lymph node metastasis (1.1% vs. 5.4%) were more frequent in group B. No clinical or sonographic feature was related to cervical lymph node metastasis in group A, while less than 45 years in age (p = 0.010), male gender (p = 0.040), capsular invasion (p<0.001), multifocality (p = 0.016) and calcification (p = 0.042) were related to cervical lymph node metastasis in group B.
  
  
  CONCLUSIONS
  The sonographic features of PTMC ≤5 mm were similar to those of PTMC >5 mm, including an irregular shape, a length/width ratio of ≥1, an unclear boundary, no peripheral halo ring, hypoechogenicity, no cystic change, calcification, no hypervascularity and no accompanying Hashimoto's thyroiditis. The clinical features of PTMC ≤5 mm were less aggressive than those of PTMC >5 mm.
authors.affiliation: Department of Ultrasound, Chinese Academy of Medical Sciences & Peking Union Medical College Hospital, Beijing, China.
authors.forename: Xingjian
authors.initials: X
authors.lastname: Lai
authors.affiliation: Department of Ultrasound, Chinese Academy of Medical Sciences & Peking Union Medical College Hospital, Beijing, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Department of Ultrasound, Chinese Academy of Medical Sciences & Peking Union Medical College Hospital, Beijing, China.
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Ultrasound, Chinese Academy of Medical Sciences & Peking Union Medical College Hospital, Beijing, China.
authors.forename: Jianchu
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Ultrasound, Chinese Academy of Medical Sciences & Peking Union Medical College Hospital, Beijing, China.
authors.forename: Ruina
authors.initials: R
authors.lastname: Zhao
authors.affiliation: Department of Ultrasound, Chinese Academy of Medical Sciences & Peking Union Medical College Hospital, Beijing, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Ultrasound, Chinese Academy of Medical Sciences & Peking Union Medical College Hospital, Beijing, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Ultrasound, Chinese Academy of Medical Sciences & Peking Union Medical College Hospital, Beijing, China.
authors.forename: Shenling
authors.initials: S
authors.lastname: Zhu
authors.affiliation: Department of Ultrasound, Chinese Academy of Medical Sciences & Peking Union Medical College Hospital, Beijing, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Department of Ultrasound, Chinese Academy of Medical Sciences & Peking Union Medical College Hospital, Beijing, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Cai
authors.affiliation: Department of Ultrasound, Chinese Academy of Medical Sciences & Peking Union Medical College Hospital, Beijing, China.
authors.forename: Yixiu
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000328:Adult; D001706:Biopsy; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging* / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D050031:Hashimoto Disease / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000473:pathology; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D013965:Thyroidectomy; D014463:Ultrasonography