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Fine-needle aspiration cytology of thyroid nodules--how well are we doing?
YS Cheung, CM Poon, SM Mak, MWM Suen, HT Leong
Department of Surgery, North District Hospital, Po Kin Road, Sheung Shui, Hong Kong
OBJECTIVES. To review the accuracy of fine-needle aspiration cytology in
diagnosing non-toxic thyroid nodules and determine what factors
are predictive of malignancy in patients with indeterminate
cytology results.
DESIGN. Retrospective study.
SETTING. Regional hospital, Hong Kong.
PATIENTS. Patients with non-toxic thyroid nodules undergoing thyroidectomy
from December 1999 to December 2003.
MAIN OUTCOME MEASURES. Sensitivity, specificity, positive and negative predictive value of
fine-needle aspiration cytology, predictive factors for malignancy
in patients with indeterminate fine-needle aspiration cytology
results.
RESULTS. The sensitivity, specificity, positive predictive value, and negative
predictive value of fine-needle aspiration cytology were 54%,
100%, 100%, and 75% respectively. For the 92 patients with
fine-needle aspiration cytology reported as �indeterminate for
malignancy�, aspiration cytology subgroup (P=0.005) and age
(P=0.001) were significant risk factors for diagnosing malignancy.
CONCLUSIONS. Fine-needle aspiration cytology has high positive predictive value
for thyroid cancer, enabling us to �rule-in� malignant lesions
with confidence. Among those with indeterminate fine-needle
aspiration cytology, atypical cell lesions and age greater than 40
years conferred increased risk of malignancy.
Hong Kong Med J 2007;13:12-5
Key words: Biopsy, needle; Frozen sections; Predictive value of tests; Thyroid nodule
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