[570] TSH Receptor mRNA in Peripheral Blood in Conjunction with Fine Needle Aspiration for the Pre-Operative Identification of Papillary Thyroid Cancer.

Natalie S Freed, Mira Milas, Deborah J Chute. Cleveland Clinic Foundation, OH

Background: Thyrotropin stimulating hormone receptor (TSHR) mRNA in peripheral blood is a newly developed test that has shown some utility in the pre-operative detection of papillary thyroid carcinoma (PTC). We assessed the accuracy of the TSHR mRNA blood test to pre-operatively identify PTC in patients undergoing thyroidectomy and investigated the impact of adding TSHR mRNA results on the sensitivity and specificity of fine needle aspiration (FNA) in detecting PTC.
Design: We retrospectively examined patients who underwent a total thyroidectomy at one institution from 2007-2010 who also had a TSHR mRNA peripheral blood test and thyroid FNA pre-operatively. Cases were included if the thyroid gland was entirely submitted for histology regardless of diagnosis, or was partially submitted with a diagnosis of PTC. TSHR mRNA peripheral blood levels were performed using quantitative PCR, and were considered positive if greater than 1.0 ng/ug. Pre-operative thyroid FNAs within the previous year were categorized as positive, atypical, or negative for PTC. For the purpose of sensitivity and specificity calculations, FNA interpretations of positive and atypical were included together as a positive result.
Results: TSHR mRNA testing demonstrated a sensitivity of 50.3% and specificity of 86.2% for the detection of PTC as illustrated in Table 1.

Thyroids stratified by TSHR mRNA status and the presence or absence of PTC

Table 1		Diagnosis
		PTC	No PTC	Total
TSHR	+	99	13	112
mRNA	-	98	81	179
	Total	197	94	291

p<0.0001

The result of TSHR mRNA testing with respect to the FNA result and the presence or absence of PTC is demonstrated in Table 2.

Thyroids stratified by TSHR mRNA status and FNA result with or without PTC

Table 2		PTC		No PTC
		TSHR mRNA +	TSHR mRNA -	TSHR mRNA +	TSHR mRNA -	Total
	Positive	37	31	0	0	68
FNA	Atypical	51	46	8	51	156
	Negative	11	21	4	28	64
	Total	99	98	12	79	288

p<0.001

The sensitivity and specificity of FNA alone in determining PTC was 83.8% and 34.0% respectively. However, when FNA and TSHR mRNA were combined with either test positive, the sensitivity increased to 89.3%, but the specificity was 29.8%. When requiring both tests to be positive, the sensitivity dropped to 44.7%, but the specificity increased to 91.2%. Of note, in the subset of cases with an atypical FNA, the specificity increased to 52.6%, with a sensitivity of 86.4% using TSHR mRNA.
Conclusions: TSHR mRNA is a useful pre-operative test in conjunction with thyroid FNA for the identification of patients with suspected PTC.
Category: Endocrine

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 81, Monday Morning