Radiologic and pathologic findings of nonpalpable thyroid carcinomas detected by ultrasonography in a medical screening center.
OBJECTIVE
The purpose of this study was to investigate the ultrasonographic and pathologic findings of nonpalpable thyroid carcinomas and reliable guidelines for fine-needle aspiration (FNA).


METHODS
Our study was approved by our Institutional Review Board, and written informed consent was waived. Between April 2004 and June 2006, screening ultrasonography was performed for 16,352 self-referred patients in the health care center. Among 1325 nonpalpable thyroid nodules in 1009 patients, pathologic results of FNA revealed 823 benign, 154 indeterminate, 198 nondiagnostic, and 150 malignant nodules. Fifty-eight malignant thyroid nodules (39 microcarcionomas and 19 carcinomas >1 cm, confirmed by both FNA and thyroidectomy) in 55 patients and 82 benign nodules (confirmed by both FNA and follow-up over 2 years) in 75 patients were included for the analysis. Three radiologists retrospectively analyzed the ultrasonographic features of these nonpalpable thyroid nodules for echogenicity, shape, margin, calcification, degree of cystic changes, and size. We compared the radiologic and pathologic findings between microcarcinomas and carcinomas larger than 1 cm for extra-capsular invasion, lymph node metastasis, bilaterality, and multicentricity using univariate analysis.


RESULTS
Marked hypoechogenicity, an irregular shape, a taller-than-wide shape, a well-defined spiculated margin, microcalcification, and an entirely solid nature were significant predictors for malignancy (P < .05), whereas a cutoff value of 1 cm in the longest diameter was not significant (P = .184). However, extracapsular invasion (P = .024) and lymph node metastasis (P = .019) were observed more frequently in carcinomas larger than 1 cm (73.7% and 42.1%, respectively) than in microcarcinomas (38.5% and 12.8%).


CONCLUSIONS
Ultrasonographic findings suggesting malignancy should be preferentially considered as indicators for FNA, regardless of size, in nonpalpable thyroid nodules. However, extracapsular invasion and lymph node metastasis are closely related to the size of the thyroid nodule.
Kim
Ji Yang
JY
Seoul National University Hospital, Healthcare Gangnam Center, Korea.
Lee
Chang Hyun
CH
Kim
Soo Young
SY
Jeon
Woo Ki
WK
Kang
Jin Hwa
JH
An
Su Kyung
SK
Jun
Woo Sun
WS
D000328:Adult; D000368:Aged; D044963:Biopsy, Fine-Needle; D002277:Carcinoma / Q000000981:diagnostic imaging* / Q000473:pathology; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D013965:Thyroidectomy; D014463:Ultrasonography