title: Incidence and histopathological behavior of papillary microcarcinomas: study of 429 cases.
abstract: OBJECTIVE
  We aim to present papillary microcarcinoma (PMC) incidence at a university teaching hospital, to compare characteristics of PMC in relation to size, and to assess for significant difference in PMC incidence among patients with non-PMC thyroid malignancies.
  
  
  METHODS
  Pathology results were reviewed for consecutive total thyroidectomies between 2002 and 2007 (n = 860). Statistical significance was calculated using chi(2) or, when unavailable, Fisher exact test.
  
  
  RESULTS
  PMC was found in 429 cases, which is 49.9 percent of all total thyroidectomies. In PMC > or =5 mm, 25.1 percent had extrathyroidal extension vs 9.1 percent for <5 mm (P < 0.001). When 4 mm is used as a threshold, P value was 300-fold smaller. Incidence in patients with any non-PMC thyroid malignancy was 51.6 percent against 47.2 percent in all other patients (P = 0.203).
  
  
  CONCLUSIONS
  In this study, PMC was found in 49.9 percent of patients, which, to our knowledge, is higher than any other reported incidence. A threshold of > or =4 mm was more significant than 5 mm for carrying increased risk for extrathyroidal spread. There was no significant difference in PMC incidence in patients with malignant vs benign disease.
authors.affiliation: McGill University, Montreal, QC, Canada. michael.pakdaman@mail.mcgill.ca
authors.forename: Michael N
authors.initials: MN
authors.lastname: Pakdaman
authors.forename: Louise
authors.initials: L
authors.lastname: Rochon
authors.forename: Olguta
authors.initials: O
authors.lastname: Gologan
authors.forename: Michael
authors.initials: M
authors.lastname: Tamilia
authors.forename: Natasha
authors.initials: N
authors.lastname: Garfield
authors.forename: Michael P
authors.initials: MP
authors.lastname: Hier
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Black
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Payne
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000453:epidemiology* / Q000473:pathology* / Q000601:surgery; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy; D047368:Tumor Burden