title: Thyroid tumours of uncertain malignant potential: frequency and diagnostic reproducibility.
abstract: The term thyroid tumours of uncertain malignant potential (TT-UMP) has been proposed for a subgroup of follicular-patterned thyroid tumours for which benignancy or malignancy cannot be assessed with certainty. The frequency, diagnostic reproducibility, immunohistochemistry and molecular genetic profiling of such tumours have been poorly explored. We, therefore, investigated (1) the frequency of TT-UMP diagnosed in a single institution (Nice, France: 2004-2008), (2) the observer variation among four pathologists, (3) whether immunohistochemical and molecular genetic profiling of TT-UMP provide additional information concerning such lesions. A series of 31 diagnosed TT-UMP (2.9%) out of 1,078 consecutive thyroidectomies were analysed. It comprised 15 follicular thyroid tumours of UMP (FT-UMP) and 16 well-differentiated tumours of UMP (WDT-UMP). Observer concordance was 70% for all TT-UMP. More than 50% of FT-UMP expressed galectin-3 and CK19, whereas more than 50% of WDT-UMP expressed HBME-1. Five cases of TT-UMP showed N-RAS mutations, while one showed H-RAS mutation and another PAX8/PPARgamma rearrangement. In conclusion, the frequency of TT-UMP is low in our institution. Diagnostic reproducibility is within the same range as other published data on follicular-patterned thyroid tumours. The ancillary methods have a low impact on aiding diagnosis of such lesions.
authors: Inserm ERI-21, Faculty of Medicine, University of Nice Sophia Antipolis, avenue de Valombrose, 06107, Nice, France. hofman@unice.fr
authors: Véronique
authors: V
authors: Hofman
authors: Sandra
authors: S
authors: Lassalle
authors: Christelle
authors: C
authors: Bonnetaud
authors: Catherine
authors: C
authors: Butori
authors: Céline
authors: C
authors: Loubatier
authors: Marius
authors: M
authors: Ilie
authors: Olivier
authors: O
authors: Bordone
authors: Patrick
authors: P
authors: Brest
authors: Nicolas
authors: N
authors: Guevara
authors: José
authors: J
authors: Santini
authors: Brigitte
authors: B
authors: Franc
authors: Paul
authors: P
authors: Hofman
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011446:Prospective Studies; D015203:Reproducibility of Results; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D013965:Thyroidectomy