title: Medullary and papillary carcinoma of the thyroid gland occurring as a collision tumour: report of three cases with molecular analysis and review of the literature.
abstract: We report the simultaneous occurrence of medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC), presenting as spatially distinct and well-defined tumour components, in three cases. In the first patient, histology, immunohistochemistry and electron microscopy demonstrated an MTC in the one nodule and PTC in two additional lesions. Non-neoplastic thyroid parenchyma separated the three nodules. Metastasis from PTC was diagnosed in a regional lymph node. Genetic analysis of both tumour components showed a distinctive mutational pattern: in the MTC a Cys634Arg substitution in exon 11 of the RET gene and in the two PTC foci a Val600Glu substitution in exon 15 of the BRAF gene. The other two patients are members of a large multigenerational family affected with familial MTC due to a germline mutation of the RET gene (Ala891Ser). Both patients harboured, besides medullary cancer and C-cell hyperplasia, distinct foci of papillary thyroid cancer, which was positive for Val600Glu BRAF mutation. Review of the literature disclosed 18 similar lesions reported and allowed the identification of different patterns of clinical presentation and biological behaviour. So far, the pathogenesis of these peculiar cases of thyroid malignancy has been completely unknown, but an underlying common genetic drive has been hypothesised. This is the first report in which two mutations, in the RET and BRAF genes, have been identified in three cases of MTC/PTC collision tumour, thus documenting the different genetic origin of these two coexisting carcinomas.
authors.affiliation: Pathology Unit, Department of Medicine, Surgery and Dentistry, Ospedale S Paolo and Ospedale Maggiore IRCCS, University of Milan School of Medicine, Milan, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Rossi
authors.forename: L
authors.initials: L
authors.lastname: Fugazzola
authors.forename: L
authors.initials: L
authors.lastname: De Pasquale
authors.forename: P
authors.initials: P
authors.lastname: Braidotti
authors.forename: V
authors.initials: V
authors.lastname: Cirello
authors.forename: P
authors.initials: P
authors.lastname: Beck-Peccoz
authors.forename: S
authors.initials: S
authors.lastname: Bosari
authors.forename: A
authors.initials: A
authors.lastname: Bastagli
mesh_terms: D000328:Adult; D018276:Carcinoma, Medullary / Q000175:diagnosis* / Q000235:genetics*; D002291:Carcinoma, Papillary / Q000175:diagnosis* / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D015513:Oncogene Proteins / Q000235:genetics*; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D013961:Thyroid Gland / Q000473:pathology / Q000648:ultrastructure; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000235:genetics*
chemical_list: D015513:Oncogene Proteins; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human; D020794:Receptor Protein-Tyrosine Kinases; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf