title: Multifocality and total tumor diameter predict central neck lymph node metastases in papillary thyroid microcarcinoma.
abstract: OBJECTIVE
  To identify the subgroup of high-risk papillary thyroid microcarcinoma (PTMC) inclined to lymph node metastasis (LNM).
  
  
  METHODS
  Patients who underwent total thyroidectomy with central neck dissection and had a pathologic diagnosis of PTMC between 2003 and 2010 at Wuhan Union Hospital were identified. The frequency of LNM was retrospectively analyzed according to the clinicopathological features. For multifocal lesions, total tumor diameter (TTD) was calculated as the sum of the maximal diameter of each lesion. Last, a meta-analysis was performed with respect to multifocality and LNM in the PTMCs.
  
  
  RESULTS
  The proportion of LNM was similar between multifocal PTMCs with TTD ≤ 1 cm and unifocal tumors with diameter ≤ 1 cm (37.5 vs. 30%, P = 0.463). LNM frequency was also similar between multifocal PTMCs with 1 < TTD ≤ 2 cm (TTD greater than 1 cm but less than or equal to 2 cm) and unifocal tumors with 1 < diameter ≤ 2 cm (56.8 vs. 64.9%, P = 0.330). However, LNM frequency was significantly higher in multifocal PTMCs with TTD > 1 cm than unifocal tumors with diameter ≤ 1 cm (60.4 vs. 30%, P < 0.001). A meta-analysis of nine publications plus our own data with a total 1,586 PTMCs demonstrated that multifocality was significantly associated with LNM risk (odds ratio 1.9, 95% confidence interval 1.5-2.4).
  
  
  CONCLUSIONS
  Multifocal PTMC with TTD > 1 cm has a similar risk of LNM as a clinical papillary cancer. Routine central neck dissection is recommended in this subgroup of patients.
authors.affiliation: Department of General Surgery, Affiliated Union Hospital, Tongji Medical College, Wuhan, China.
authors.forename: Qunzi
authors.initials: Q
authors.lastname: Zhao
authors.forename: Jie
authors.initials: J
authors.lastname: Ming
authors.forename: Chunping
authors.initials: C
authors.lastname: Liu
authors.forename: Lan
authors.initials: L
authors.lastname: Shi
authors.forename: Xia
authors.initials: X
authors.lastname: Xu
authors.forename: Xiu
authors.initials: X
authors.lastname: Nie
authors.forename: Tao
authors.initials: T
authors.lastname: Huang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000175:diagnosis* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D037981:Neck Dissection; D009367:Neoplasm Staging; D011379:Prognosis; D012307:Risk Factors; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000601:surgery; D055815:Young Adult