[623] Papillary Thyroid Microcarcinoma: Clinicopathological Correlation with BRAF V600E Mutation

Renu K Virk, Alexander Finkelstein, Avinash Prasad, Pei Hui, Tobias Carling, Sanziana A Roman, Julie A Sosa, Robert Udelsman, Manju Prasad. Yale School of Medicine, New Haven, CT; New York University, New York, NY; Hartford Hospital, Hartford, CT

Background: Papillary thyroid microcarcinoma (PTMC: papillary carcinoma ≤1cm) are increasingly being detected due to the frequent use of ultrasonography. Their biology and management remains controversial despite the excellent prognosis. In recent years BRAF V600E mutation has emerged as a marker of aggressive behavior in papillary thyroid carcinoma (PTC) but its significance in PTMC is not clear.
Design: Clinical and histopathological features were reviewed in 90 PTMCs. The latter included histologic variant, tumor interface with non-neoplastic thyroid, nuclear features of PTC (well-developed or subtle), presence of cystic change, tall or polygonal eosinophilic (plump pink) cells, extrathyroidal extension (ETE), tumor-associated fibrosis/sclerosis/desmoplasia, stromal calcification, psammoma bodies and osteoclast-like multinucleated giant cells. These features were correlated with BRAF V600E mutational analysis performed in all cases by single strand confirmation polymorphism.
Results: Table 1 summarizes significant clinicopathological differences in BRAF V600E mutation positive and negative PTMCs.

Clinicopathologic features (n=90)	BRAF V600E mutation positive (n=66;73%)	BRAF V600E mutation negative (n=24; 27%)	p value
Subcapsular sclerosing variant (n=30; 33%)	26 (87%)	4 (13%)	0.04
Follicular variant (n=10; 11%)	3 (30%)	7 (70%)	0.003
Lymph node positive (n=20/65; 31%)	19 (95%)	1 (5%)	0.01
Extrathyroidal extension (n=3; 3.4%)	3 (100%)	0
Infiltrative interface with adjacent thyroid (n=72; 78%)	60 (83%)	12 (17%)	0.0001
Stromal fibrosis/desmoplasia/Sclerosis (n=79; 86%)	63 (79%)	16 (21%)	0.0009
Classic well-developed nuclear features of PTC (n=73; 80%)	59 (81%)	14 (19%)	0.001
Multinucleated Giant cells (n=29; 31%)	26 (90%)	3 (10%)	0.02

No significant difference was found between the two groups of PTMCs in age, sex, tumor size, multifocality, psammoma bodies, stromal calcification, cystic change and polygonal eosinophilic tumor cells.
Conclusions: BRAF V600E mutation was significantly associated with the subcapsular sclerosing variant of PTMC but not with the follicular variant, and with lymph node metastasis. Histological features characteristic of BRAF V600E mutation positive tumors included infiltrative interface with non-neoplastic thyroid, stromal fibrosis/sclerosis/desmoplasia, well-developed characteristic nuclear features of PTC and multinucleated osteoclast-like giant cells.
Category: Endocrine

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 20, Tuesday Afternoon