Simple and complex fibroadenomas: are there any distinguishing sonographic features?

Objectives: Complex fibroadenomas are fibroadenomas harboring 1 or more complex pathologic features: epithelial calcifications, apocrine metaplasia, sclerosing adenosis, and cysts larger than 3 mm. No sonographic features have been clearly defined for the distinction of simple fibroadenomas from complex ones, which are associated with an increased cancer risk. We aimed to evaluate the accuracy of sonographic features for the prediction of complexity in fibroadenomas.

Methods: A total of 252 fibroadenomas were found at consecutive percutaneous needle or excisional surgical biopsy. Sixty-three were excluded because their respective imaging examinations were not recorded on digital support and consequently were not available. According to histologic diagnoses, fibroadenomas (n = 189) were classified into simple (n = 159) and complex (n = 30). The size, number, and sonographic features were assessed, and their respective accuracy rates for prediction of complexity were analyzed.

Results: All patients were women. Complex fibroadenomas presented more frequently as solitary nodules (n = 21 [70%]) and were significantly larger than simple fibroadenomas (1.9 versus 1.3 cm; P = .009). Image predictors of complexity were an irregular shape (P< .001), noncircumscribed contours (indistinct, angular, microlobulated, or spiculated; P < .001), a complex echo structure (P < .001), the presence of microcalcifications (P = .002), and posterior acoustic enhancement (P < .001). By logistic multivariate regression, a complex echo structure (odds ratio [OR], 9.5; 95% confidence interval [CI], 2.8-32.3), noncircumscribed contours (OR, 3.7; 95% CI, 1.1-12.8), and posterior acoustic enhancement (OR, 4.0; 95% CI, 1.1-14.6) were independent predictors of complexity. Receiver operating characteristic curve analysis showed that a complex echo structure was the most accurate sonographic finding for identification of complex fibroadenomas (area under the curve, 0.74).

Conclusions: Certain sonographic features are associated with complex fibroadenomas and can help the radiologist decide which ones require biopsy.