Poster The Annual Scientific Meeting of the Endocrine Society of Australia and the Society for Reproductive Biology 2013

Thyroid FNA BRAF positivity correlates with a higher grade bethesda category (#364)

Catherine Woolnough 1 2 , Colin Moncrieff 2 , Michael Elliott 2 3 , Ruta Gupta 4 , Jonathan Clarke 3 , Ash Gargya 1 , Paul Williams 1 2 , Susan McLennan 1 2 , Elizabeth Chua 1 2
  1. Department of Endocrinology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
  2. Sydney Medical School, University of Sydney, Sydney, NSW, Australia
  3. Sydney Head and Neck Cancer Institute, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
  4. 4. Department of Diagnostic Oncology and Tissue Pathology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia

Introduction
Mutations in the BRAF oncogene have been linked to papillary thyroid cancer (PTC) in various populations, worldwide. Testing for BRAF in fine needle aspirations from thyroid in addition to cytology results may improve the diagnosis of PTC. This study describes the incidence of the V600E BRAF mutation (BRAF+ve) in a Sydney population with papillary thyroid cancer (PTC), and examines its correlation with the corresponding FNA Bethesda category.

Methods
Thyroid tissue was obtained from 73 patients who had thyroidectomies at Royal Prince Alfred Hospital. DNA was extracted from fine needle aspiration (FNA), fresh frozen tissue or paraffin blocks. BRAF+ve was detected by melt curve analysis and confirmed by DNA sequencing. In a subgroup of patients, results for FNA and tissue were compared for Bethesda category, histopathology diagnoses and presence of BRAF+ve.

Results
Of the 73 cases, 37 were histologically confirmed PTC. Of these, 32 were classic and 5 were follicular variant. BRAF+ve was detected in 24/37 (65%) PTC. Of the classic variant, 22/32 (69%) were BRAF+ve compared to 2/5 (40%) in those with the follicular variant.

Of the 73 cases, 30 had FNA Bethesda classification. On histopathology, 13 were PTC and 17 were benign. 10/13 PTC cases were BRAF+ve, all were the classic variant of PTC and Bethesda category V-VI (Table 1). 3/13 PTC were BRAF-ve, all were follicular variant and Bethesda III, V and V (Table 1). The 17 benign nodules were all BRAF-ve and ranged from Bethesda II-V (Table 2).

1065-Tables1and2.JPG

Conclusions
The BRAF mutation incidence is similar to those described in other Australian and American populations with a higher incidence in the classic variant. Although not all PTC are BRAF+ve, a positive result can be very helpful in improving the predictive risk of malignancy especially in thyroid nodules with indeterminate cytology.