Thyroid nodule shape suggests malignancy

Objective: To evaluate if a nodule with shape taller than wide (anteroposterior/transverse diameter ratio, A/TR1) is a good predictor of malignancy independent of the size. Methods: We retrospectively examined the cytological and histological results of 7455 nodules (5198 patients) referred for ultrasound-guided-fine needle aspiration cytology (US-FNAC) in our hospital from January 1991 to September 2004. Results: AsuitableFNACwasobtainedfrom6135nodules(4495patients);34.6%werelessthan1 cmin diameter (small nodules, SN). A diagnosis of carcinoma was histologically confirmed in 284/349 suspicious lesions after FNAC. The size of carcinoma nodules was not significantly associated with the occurrenceofextracapsulargrowth(largenodules(LN):10.5%,SN:4.9%,NS)andlymphnodemetastasis (LN: 23.6%, SN: 25.0%, NS). Malignant lesions showed microcalcifications more frequently than benign nodules (72.2 vs 28.7%; P!0.001; (odds ratio, OR(confidence intervals, CI)Z9.9(7.2‐13.4)). Similarly, A/TR1 (76 vs 40%; P!0.001; OR(CI)Z8.6(5.5‐13.1)), blurred margins (52.8 vs 18.8%; P!0.001; OR(CI)Z7.7(5.6‐10.2)), solid hypo-echoic appearance (80.6 vs 52.4%; P!0.001; OR(CI)Z 3.2(2.2‐4.3)) and intranodular vascular pattern (type 2) (61.6 vs 49.7%; P!0.001; OR(CI)Z 1.7(1.3‐2.3)) were significantly more frequent in malignant than in benign nodules. Conclusions:Ourdatashowthatnosingleparameter,includingnodulesize,satisfactorilyidentifiesasubset ofpatientstobeelectivelyinvestigatedbyFNAC.WeconcludedthatA/TR1withatleasttwoofUSfeatures (microcalcification, blurred margins,hypo-echoicpattern) istoday the best compromisebetween missing cancers and cost‐benefit.