Absence of BRAF, NRAS, KRAS, HRAS mutations, and RET/PTC gene rearrangements distinguishes dominant nodules in Hashimoto thyroiditis from papillary thyroid carcinomas.
Dominant nodules within Hashimoto thyroiditis (HT) may present with unique morphological features that overlap with but are not diagnostic of papillary thyroid carcinoma (PTC). Activating BRAF point mutations, RAS aberrations, and RET rearrangements are mutually exclusive events in the oncogenesis of papillary thyroid carcinoma, and RET rearrangements have been previously described in dominant nodules of HT. We identified 28 cases of Hashimoto thyroiditis with a dominant nodule, from 345 consecutive HT thyroidectomies. Screening for BRAF, RET, KRAS, NRAS, and HRAS mutations, as well as RET-PTC1 and RET-PTC3 rearrangements, was performed on paraffin-embedded material from 17 of these dominant nodules. Patients ranged in age from 29 to 76 years and were predominantly female, and the nodules ranged from 1.5 to 6.2 cm. No BRAF or RAS mutations or RET-PTC rearrangements were identified in a dominant nodule, including those with atypical, worrisome histopathologic features. Of ten cases with diagnostic concomitant or incidental papillary carcinoma, three had a V600E point mutation in BRAF, and one case had a BRAF exon 15 deletion (600-604E), while the dominant nodules were negative for mutation, supporting the notion that dominant nodules are neither malignant nor precursor lesions, and strict histological, clinical, and molecular criteria must be met for the diagnosis of papillary thyroid carcinoma.
Sadow
Peter M
PM
Pathology Service, WRN219, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA. psadow@partners.org
Heinrich
Michael C
MC
Corless
Christopher L
CL
Fletcher
Jonathan A
JA
Nosé
Vânia
V
D000231:Adenocarcinoma, Papillary / Q000235:genetics* / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D015321:Gene Rearrangement; D005838:Genotype; D050031:Hashimoto Disease / Q000235:genetics* / Q000473:pathology*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D009154:Mutation; D000072079:Patched Receptors; D011518:Proto-Oncogene Proteins / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D051096:Proto-Oncogene Proteins c-ret / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000473:pathology*; D018631:ras Proteins / Q000235:genetics
C117307:KRAS protein, human; D000072079:Patched Receptors; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins