title: 'Incidental' and 'non-incidental' thyroid papillary microcarcinomas are two different entities.
abstract: OBJECTIVE
  Papillary thyroid microcarcinomas (microPTC) may be 'incidental' (Inc-microPTC), occasionally found at histology after surgery for benign disease or 'non-incidental' (Non-Inc-microPTC), diagnosed on clinical grounds. It is unclear whether these different microPTC reflect the same disease. The aim of the study was to compare Inc-microPTC and Non-Inc-microPTC for clinical and histological features as well as for serum TSH, a known factor involved in PTC development.
  
  
  METHODS
  We evaluated histology and serum TSH levels of consecutive patients submitted to thyroidectomy for goiter with compressive symptoms or for cytological diagnosis suspicious/indicative of PTC.
  
  
  METHODS
  In total, 665 consecutive patients (259 with a single thyroid nodule, SN and 406 with a multinodular gland, MN) were included in the study. According to histology, patients were classified as: benign nodular goiter (Benign, n=291); Inc-microPTC (n=92); Non-Inc-microPTC (n=67) and PTC≥1cm (macroPTC, n=215).
  
  
  RESULTS
  Inc-microPTC were significantly more frequent in MN than in SN (66/406, 16.2% vs 26/259, 10.0%, P=0.02). Patients with Inc-microPTC compared with Non-Inc-microPTC were older (mean age±s.d. 53.3±13.2 years vs 44.9±14.8 years, P=0.0002), had a smaller tumor size (median 4mm vs 9mm, P<0.0001), a higher frequency of multifocality (70/92, 76.1% vs 35/67, 52.2% P=0.001) and lower levels of TSH (median 0.6mIU/L, IR: 0.4-1.0mIU/L vs value 1. mIU/L, IR: 0.6-1.4mIU/L vs P=0.0001).
  
  
  CONCLUSIONS
  Incidental and non-incidental papillary thyroid microcarcinomas appear to be two different entities.
authors.affiliation: Department of Clinical and Experimental Medicine Endocrinology and Metabolism Section, University of Pisa, Pisa, Italy.
authors.forename: Maria Annateresa
authors.initials: MA
authors.lastname: Provenzale
authors.affiliation: Department of Clinical and Experimental Medicine Endocrinology and Metabolism Section, University of Pisa, Pisa, Italy e.fiore@ao-pisa.toscana.it.
authors.forename: Emilio
authors.initials: E
authors.lastname: Fiore
authors.affiliation: Department of Surgical Pathology, Medical, Molecular and Critical Area University of Pisa, Pisa, Italy.
authors.forename: Clara
authors.initials: C
authors.lastname: Ugolini
authors.affiliation: Department of Surgical Pathology, Medical, Molecular and Critical Area University of Pisa, Pisa, Italy.
authors.forename: Liborio
authors.initials: L
authors.lastname: Torregrossa
authors.affiliation: Department of Clinical and Experimental Medicine Statistics Section, University of Pisa, Pisa, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Morganti
authors.affiliation: Department of Clinical and Experimental Medicine Endocrinology and Metabolism Section, University of Pisa, Pisa, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Molinaro
authors.affiliation: Department of Surgical Pathology, Medical, Molecular and Critical Area University of Pisa, Pisa, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Miccoli
authors.affiliation: Department of Surgical Pathology, Medical, Molecular and Critical Area University of Pisa, Pisa, Italy.
authors.forename: Fulvio
authors.initials: F
authors.lastname: Basolo
authors.affiliation: Department of Clinical and Experimental Medicine Endocrinology and Metabolism Section, University of Pisa, Pisa, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Vitti
mesh_terms: D000328:Adult; D000368:Aged; D002291:Carcinoma, Papillary / Q000097:blood / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006044:Goiter, Nodular / Q000097:blood / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D033162:Incidental Findings; D008297:Male; D008875:Middle Aged; D013964:Thyroid Neoplasms / Q000097:blood / Q000000981:diagnostic imaging / Q000473:pathology*; D016606:Thyroid Nodule / Q000097:blood / Q000000981:diagnostic imaging / Q000473:pathology*; D013972:Thyrotropin / Q000097:blood*
chemical_list: D013972:Thyrotropin