title: Features Predictive of Distant Metastasis in Papillary Thyroid Microcarcinomas.
abstract: BACKGROUND
  The recent increase in the incidence of thyroid cancer has been mainly attributed to papillary thyroid microcarcinomas (PTMCs), and many studies have suggested conservative strategies for the diagnosis and treatment of PTMC. However, PTMCs may be associated with distant metastasis. This study aimed to evaluate the clinicopathological features and identify the risk factors for distant metastasis in patients with PTMCs.
  
  
  METHODS
  The medical records of 8808 patients who were diagnosed with PTMC from 1999 to 2012 were reviewed, and 12 (0.1%) patients with distant metastasis were identified. Forty-one PTMC patients who initially had lateral cervical lymph node (LN) metastasis and were cured with no evidence of a distant metastasis were also selected as a control group.
  
  
  RESULTS
  Of the 12 patients with distant metastasis, nine had synchronous metastasis and three had metachronous metastasis. All 12 patients had primary tumors >0.5 cm and cervical LN metastasis at initial surgery. Ten patients had clinically apparent lateral cervical LN metastases, while two patients had only microscopic involvement of a central LN. Four patients died of thyroid carcinoma. Disease-specific mortality was associated with old age, large metastatic LNs with extranodal extension, and aggressive pathologic subtype of metastatic LNs. When the clinicopathological features of the patients with distant metastasis were compared with the control patients, the presence of extranodal extension and change to an aggressive pathologic subtype of metastatic LNs were significantly associated with distant metastasis and persistent structural distant PTMC metastasis.
  
  
  CONCLUSIONS
  Most patients with PTMC demonstrate excellent clinical outcomes, and distant metastases rarely occur. However, distant metastasis of PTMC can be fatal. Performing a meticulous pathologic examination of metastatic LNs to identify the presence of extranodal extension and the pathologic subtype of metastatic LNs helps to assess the risk of a distant metastasis in patients with PTMC.
authors.affiliation: 1 Department of Internal Medicine, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Min Ji
authors.initials: MJ
authors.lastname: Jeon
authors.affiliation: 1 Department of Internal Medicine, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Won Gu
authors.initials: WG
authors.lastname: Kim
authors.affiliation: 1 Department of Internal Medicine, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Yun Mi
authors.initials: YM
authors.lastname: Choi
authors.affiliation: 1 Department of Internal Medicine, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Hyemi
authors.initials: H
authors.lastname: Kwon
authors.affiliation: 2 Department of Surgery, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Yu-Mi
authors.initials: YM
authors.lastname: Lee
authors.affiliation: 2 Department of Surgery, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Tae-Yon
authors.initials: TY
authors.lastname: Sung
authors.affiliation: 2 Department of Surgery, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Jong Ho
authors.initials: JH
authors.lastname: Yoon
authors.affiliation: 2 Department of Surgery, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Ki-Wook
authors.initials: KW
authors.lastname: Chung
authors.affiliation: 2 Department of Surgery, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Suck Joon
authors.initials: SJ
authors.lastname: Hong
authors.affiliation: 1 Department of Internal Medicine, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Tae Yong
authors.initials: TY
authors.lastname: Kim
authors.affiliation: 1 Department of Internal Medicine, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Young Kee
authors.initials: YK
authors.lastname: Shong
authors.affiliation: 3 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: 1 Department of Internal Medicine, University of Ulsan College of Medicine , Seoul, Korea.
authors.forename: Won Bae
authors.initials: WB
authors.lastname: Kim
mesh_terms: D000328:Adult; D001706:Biopsy; D002291:Carcinoma, Papillary / Q000401:mortality / Q000556:secondary* / Q000601:surgery; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013964:Thyroid Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D047368:Tumor Burden