title: Features of papillary thyroid microcarcinoma associated with lateral cervical lymph node metastasis.
abstract: OBJECTIVE
  Papillary thyroid microcarcinoma (PTMC) has an excellent prognosis with an indolent disease course. However, some PTMCs have an aggressive course with lateral cervical lymph node (LCLN) metastasis or distant metastasis. This study aimed to evaluate the pre-operative features of PTMC associated with LCLN metastasis.
  
  
  METHODS
  This retrospective cohort study with a nested, matched case-control design included 199 PTMC patients with LCLN metastasis at initial surgery (N1b group) and 196 PTMC patients without any LN metastasis or persistent disease (N0 NED group) as controls; primary tumour sizes were matched.
  
  
  RESULTS
  Compared with the N0 NED group, the N1b group was younger (<50 years) and more likely to be male (P = 0·002 and P = 0·003, respectively). On pre-operative neck ultrasonography (US), N1b group PTMCs were more commonly associated with a location in the upper lobes of the thyroid, or in the subcapsular area and microcalcifications than N0 NED group PTMCs (all P < 0·001). An increase in the number of these features was significantly associated with a higher risk of LCLN metastasis (P < 0·001). Evaluation of the clinical and pre-operative US characteristics of 26 patients with confirmed LCLN recurrence after initial treatment of clinical N0 PTMCs revealed that the distribution of the number of suspicious features in these patients was similar to that of the N1b group.
  
  
  CONCLUSIONS
  Papillary thyroid microcarcinomas in young (<50 years) or male patients, with an upper lobe or subcapsular location, and with microcalcification have a higher risk of LCLN metastasis. Individualized management according to the number of these suspicious features may be needed for small thyroid nodules.
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Min Ji
authors.identifier: http://orcid.org/0000-0002-1297-107X
authors.initials: MJ
authors.lastname: Jeon
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Mi Sun
authors.initials: MS
authors.lastname: Chung
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Hyemi
authors.initials: H
authors.lastname: Kwon
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Mijin
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Suyeon
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jung Hwan
authors.initials: JH
authors.lastname: Baek
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Dong Eun
authors.initials: DE
authors.lastname: Song
authors.affiliation: Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Tae-Yon
authors.initials: TY
authors.lastname: Sung
authors.affiliation: Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Suck Joon
authors.initials: SJ
authors.lastname: Hong
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Tae Yong
authors.initials: TY
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Won Bae
authors.initials: WB
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Young Kee
authors.initials: YK
authors.lastname: Shong
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jeong Hyun
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Won Gu
authors.initials: WG
authors.lastname: Kim
mesh_terms: D000328:Adult; D002114:Calcinosis; D002291:Carcinoma, Papillary / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000473:pathology*; D014463:Ultrasonography