title: Cell proliferation marker MCM2, but not Ki67, is helpful for distinguishing between minimally invasive follicular carcinoma and follicular adenoma of the thyroid.
abstract: OBJECTIVE
  To compare cell proliferation markers, minichromosome maintenance protein 2 (MCM2) and Ki67, in minimally invasive follicular carcinoma (MIFC) and follicular adenoma (FA) of the thyroid and among MIFCs with different diagnostic criteria.
  
  
  RESULTS
  Twenty-two MIFCs and 20 FAs were immunohistochemically stained for MCM2 and Ki67. The MIFCs were subdivided into six Group 1 tumours with both capsular and vascular invasions, seven Group 2 tumours with vascular invasion only and nine Group 3 tumours with capsular invasion only. The MCM2 and Ki67 indices were calculated, counting more than 1000 tumour cells in the most frequently positive areas. In total and Groups 1-3 MIFCs and in FAs, the average MCM2 index was 26.7 +/- 11.0, 28.4 +/- 8.6, 26.3 +/- 14.8, 25.9 +/- 8.4 and 10.7 +/- 4.5, respectively, whereas the average Ki67 index was 2.07 +/- 1.65, 1.93 +/- 2.02, 2.49 +/-1.38, 1.84 +/- 1.5 and 1.78 +/- 0.92, respectively. There was a significant difference in the MCM2 index, but not in the Ki67 index, between each category of MIFCs and FA (P < 0.01). However, neither the MCM2 index nor the Ki67 index showed a statistically significant difference among the subgroups of MIFC.
  
  
  CONCLUSIONS
  MCM2, but not Ki67, is a helpful marker for differentiating MIFC from FA. The tumour cell proliferative activity supports the histological criteria based on diagnosing MIFC by either capsular or vascular invasion only.
authors.affiliation: Department of Pathology, Nagoya City University Medical School, Nagoya, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Cho Mar
authors.forename: T
authors.initials: T
authors.lastname: Eimoto
authors.forename: S
authors.initials: S
authors.lastname: Nagaya
authors.forename: H
authors.initials: H
authors.lastname: Tateyama
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000378:metabolism / Q000473:pathology*; D000236:Adenoma / Q000378:metabolism / Q000473:pathology*; D018797:Cell Cycle Proteins / Q000032:analysis*; D049109:Cell Proliferation; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000032:analysis*; D064111:Minichromosome Maintenance Complex Component 2; D009687:Nuclear Proteins / Q000032:analysis*; D013964:Thyroid Neoplasms / Q000378:metabolism / Q000473:pathology*
chemical_list: D018797:Cell Cycle Proteins; D019394:Ki-67 Antigen; D009687:Nuclear Proteins; C084859:MCM2 protein, human; D064111:Minichromosome Maintenance Complex Component 2