title: Central lymph node metastasis in papillary thyroid microcarcinoma can be stratified according to the number, the size of metastatic foci, and the presence of desmoplasia.
abstract: BACKGROUND
  Lymph node (LN) metastasis is common in papillary thyroid microcarcinoma (PTMC). The aim of this study was to investigate the impact of LN metastasis and its risk stratification on PTMC recurrence.
  
  
  METHODS
  We retrospectively reviewed the data of 336 patients with PTMC who underwent surgery from 2005 to 2006 at a single institution. LN metastasis was stratified according to the number of metastatic LNs, the ratio of metastatic to removed LNs, the size of metastatic foci in LNs, and the presence of extranodal extension and desmoplasia.
  
  
  RESULTS
  Of the 336 patients, 93 (28%) had LN metastasis. During the follow-up of 5.3 years, 16 (4.8%) experienced locoregional recurrence. Among several clinicopathologic factors, LN metastasis was the most important risk factor for recurrence (P = .02). Lateral LN metastasis was correlated with recurrence-free survival (P < .01), whereas central LN metastasis was not (P = .20). When central LN metastasis was stratified, a high number of metastatic LNs (≥3), larger metastatic foci (≥0.2 cm), and the presence of desmoplasia were associated with recurrence-free survival (P < .05).
  
  
  CONCLUSIONS
  The prognostic significance of central LN metastasis can differ according to the number of metastatic LNs, the size of metastatic foci, and the presence of desmoplasia. Patients with a high number of metastatic LNs, larger metastatic foci, and presence of desmoplasia in LNs should be treated aggressively and supervised carefully for PTMC recurrence.
authors.affiliation: Department of Pathology, Korea Cancer Center Hospital, Seoul, Republic of Korea; Department of Pathology, Samsung Medical Center, Seoul, Republic of Korea.
authors.forename: Soo Youn
authors.initials: SY
authors.lastname: Cho
authors.affiliation: Department of Radiology, Korea Cancer Center Hospital, Seoul, Republic of Korea.
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Korea Cancer Center Hospital, Seoul, Republic of Korea.
authors.forename: Yun Hyi
authors.initials: YH
authors.lastname: Ku
authors.affiliation: Department of Internal Medicine, Korea Cancer Center Hospital, Seoul, Republic of Korea.
authors.forename: Hong Il
authors.initials: HI
authors.lastname: Kim
authors.affiliation: Department of Otorhinolaryngology, Korea Cancer Center Hospital, Seoul, Republic of Korea.
authors.forename: Guk Haeng
authors.initials: GH
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Korea Cancer Center Hospital, Seoul, Republic of Korea. Electronic address: chorong24@gmail.com.
authors.forename: Min Joo
authors.initials: MJ
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D002291:Carcinoma, Papillary / Q000473:pathology*; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000209:etiology*; D012189:Retrospective Studies; D018570:Risk Assessment; D013964:Thyroid Neoplasms / Q000473:pathology*; D055815:Young Adult