[422] Relative Sensitivity of Fine Needle Aspiration by Tumor Type and Size

Andrew A Renshaw, Vickie Y Jo, Jeffrey F Krane. Baptist Hospital of Miami, Miami, FL; Brigham and Women's Hospital & Harvard Medical School, Boston, MA

Background: Fine-needle aspiration (FNA) of papillary thyroid carcinoma has overall high sensitivity. Previous studies have shown correlation between FNA sensitivity and size of papillary thyroid carcinoma, and lower sensitivity for follicular variant of papillary carcinoma. Data on other types of thyroid carcinomas are lacking.
Design: We reviewed the results of 997 resected thyroid carcinomas at two institutions (5/1/2005 - 8/2011; 1/1999 to 11/2009), and correlated the findings with clinical and cytologic information. FNA diagnoses were classified according to The Bethesda System for Reporting Thyroid Cytopathology, and FNA diagnoses of "Malignant", "Suspicious for Malignancy", and "Suspicious for Follicular/Oncocytic Neoplasm" were considered "positive". Overall sensitivity of FNA and sensitivities based on size groups (≤1.0 cm, 1-3 cm, ≥3.0 cm) were calculated using "positive" FNAs as the numerator for each malignancy type.
Results: There were 868 papillary carcinomas (including 371 follicular variants), 101 follicular carcinomas (including 31 oncocytic variants), 16 medullary carcinomas, and 12 poorly differentiated carcinomas. The mean size of classical papillary carcinoma (1.9 cm, range 0.3-6.5 cm) was significantly smaller than for follicular variant of papillary carcinoma (2.2 cm, range 0.3-9.5 cm), follicular carcinoma, oncocytic variant (3.0 cm, range 0.4-10.0 cm), follicular carcinoma (3.0 cm, range 0.6-9.5 cm), and poorly differentiated carcinoma (2.8 cm, range 1.2-6.4 cm) (p < 0.003 for each), but not for medullary carcinoma (1.7 cm, range 0.6-3.3 cm) (p = 0.45). FNA sensitivities based on size groups are shown in Table 1.

Table 1: FNA Sensitivity by Tumor Type and Size

	≤1.0 cm	1-3 cm	≥3.0 cm	Overall Sensitivity
Papillary Carcinoma	88%	91%	77%	88%
Follicular Variant of Papillary Carcinoma	74%	79%	77%	78%
Follicular Carcinoma	67%	70%	72%	71%
Follicular Carcinoma, Oncocytic Variant	50%	83%	100%	84%
Medullary Carcinoma	100%	89%	100%	94%
Poorly Differentiated Carcinoma	N/A	100%	100%	100%

Conclusions: We conclude FNA is more sensitive overall for classic papillary carcinomas and medullary carcinomas, because they have characteristic cytologic features, compared to other thyroid malignancies. FNAs are less sensitive for small (≤1 cm) follicular based lesions. For follicular carcinoma and oncocytic (Hurthle) variant of follicular carcinoma, FNA sensitivity improves with size beyond 3 cm.
Category: Cytopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 50, Wednesday Afternoon