title: Trisomy 17 as a marker for a subset of noninvasive thyroid nodules with focal features of papillary carcinoma: cytogenetic and molecular analysis of 62 cases and correlation with histological findings.
abstract: BACKGROUND
  Differentiated carcinomas of the thyroid are divided into follicular thyroid carcinoma and papillary thyroid carcinoma (PTC), based on their propensity to invade and their cytological features [papillary carcinoma-type nuclear changes (PTC-NCs)]. PTC typically exhibits a diploid karyotype sometimes with inv10(q11.2q21.2), leading to rearranged RET gene. Follicular thyroid carcinomas are often aneuploid and may exhibit t(2;3)(q13;p25), resulting in PAX8-PPARgamma1 gene fusion. Isolated trisomy 17 has rarely been reported in thyroid lesions, and its significance is unknown.
  
  
  OBJECTIVE
  Our objective was to determine whether isolated trisomy 17 corresponds to a specific histological or molecular thyroid tumor subset. Nine cases with isolated trisomy 17 were critically reviewed and investigated for RAS and BRAF mutations and for RET and PAX8-PPARgamma1 rearrangements.
  
  
  RESULTS
  All nine cases were noninvasive, exhibited follicular growth pattern, and showed PTC-NCs focally defined within the nodule: four were PTCs follicular variant within larger tumors, and five were follicular-patterned nodules with incomplete cytological features of papillary carcinoma (variable proportion of cells with PTC-NCs scattered inside the lesion). RAS, BRAF V600E mutation, RET or PAX8-PPARgamma1 rearrangements were not identified. One case had BRAF K601E mutation. Only two of the 53 control cases showed focal PTC-NCs.
  
  
  CONCLUSIONS
  Isolated trisomy 17 is associated with focal papillary carcinoma changes in follicular-patterned thyroid nodules and may be a marker for this subset of thyroid lesions that are often difficult to classify.
authors.affiliation: Dipartimento di Scienze e Tecnologie Biomediche, University of Cagliari, 09042 Monserrato CA, Italy.
authors.forename: Daniela V
authors.initials: DV
authors.lastname: Frau
authors.forename: Maria L
authors.initials: ML
authors.lastname: Lai
authors.forename: Paola
authors.initials: P
authors.lastname: Caria
authors.forename: Tinuccia
authors.initials: T
authors.lastname: Dettori
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Coni
authors.forename: Gavino
authors.initials: G
authors.lastname: Faa
authors.forename: Luca
authors.initials: L
authors.lastname: Morandi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tallini
authors.forename: Roberta
authors.initials: R
authors.lastname: Vanni
mesh_terms: D000328:Adult; D002291:Carcinoma, Papillary / Q000235:genetics* / Q000473:pathology*; D002886:Chromosomes, Human, Pair 17; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D006801:Humans; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D009154:Mutation; D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D051096:Proto-Oncogene Proteins c-ret / Q000235:genetics; D017422:Sequence Analysis, DNA; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000473:pathology*; D014314:Trisomy / Q000235:genetics / Q000473:pathology*; D018631:ras Proteins / Q000235:genetics
chemical_list: D004273:DNA, Neoplasm; D000072636:PAX8 Transcription Factor; C083325:PAX8 protein, human; D051761:Paired Box Transcription Factors; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D018631:ras Proteins