Mucinous Carcinoma of the Breast: Diagnostic Criteria Based on Ultrasonography

Abstract

In previous studies, the benign imaging features of mucinous carcinoma (MCA) of the breast that may result in missing the diagnosis have been reported. The aim of this study was to evaluate the diagnostic criteria from ultrasonography of MCA of the breast, and to investigate the general applicability of ultrasonographic features in diagnosing this tumor. We retrospectively reviewed the ultrasonographic findings of 41 (34 pure MCA and 7 mixed MCA) pathologically-confirmed cases of MCA of the breast. We analyzed the size, shape, margin, internal echogenicity, echotexture, intratumoral calcification, posterior acoustic enhancement, and surrounding desmoplastic reaction. The original sonogram report of each case was categorized based on the American College of Radiology Breast Imaging Reporting and Data System (ACR BI-RADS) for ultrasound assessment categories. The median age of the patients was 52 years (range, 34—96 years). The median tumor size was 2.6 cm (range, 0.8—15 cm). Tumor size was found to significantly correlate with the duration of lesion palpability. Lobular shape (53.7%), microlobulated margin (65.9%) and mildly hypoechoic echogenicity (53.7%) were the most frequent sonographic findings. Multiple linear regression showed that tumor type was the only predictor of the presence and sonogram appearances of lymph nodes. In all cases, when the width-to-anteroposterior dimension ratio, either being less than or greater than 1.4, was taken into consideration, no significant correlation with any of the variables stated above was found. Posterior enhancement was detected in most cases, accounting for about 19.5% of the characteristics of larger tumor size, heterogeneous echotexture or evidence of mixed MCA. Most sonogram reports disclosed a suspicion of or definite malignancy in 38 cases (92.7%). The sensitivity of malignant sonographic features with traditional lexicons was poor for MCA of the breast, which supports the assumption of the less invasive nature of this tumor. The deformed ovoid shape is useful for suspecting a nontypical benign lesion, and we noted a high positive reporting rate of suspicion of malignancy. Posterior enhancement occurs quite often in MCA due to its tissue characteristics.