Differential diagnosis of breast mucinous carcinoma with oval shape from fibroadenoma based on ultrasonographic features

Abstract

Abstract Background Approximately 50% of breast mucinous carcinomas (MCs) are oval and have the possibility of being misdiagnosed as fibroadenoma (FA). We aimed to identify the key features that can help differentiate breast MC with oval shape from fibroadenoma (FA) on ultrasonography (US). Methods Seventy-six MCs in 71 consecutive patients and 50 FAs with oval shape in 50 consecutive patients were included in our study. All lesions had pathological diagnoses. According to the Breast Imaging Reporting and Data System (BI-RADS), first, the ultrasonographic features of the MCs and FAs were recorded and a final category was assessed. Then, the differences of ultrasonographic characteristics between category 4A (low-risk group) and category 4B-5 (medium-high risk group) of MCs were identified. Finally, other ultrasonographic features of MC and FA both with oval shape were compared to determine the key factors for differential diagnosis. The Mann-Whitney test, the χ2 test or Fisher’s exact test was used in our study. Results MCs with oval shape (81.2%) and circumscribed margin (25%) on US were more common assessed in the low-risk group (BI-RADS 4A) than in the medium-high risk group (BI-RADS 4B-5) (20%，p<0.001 and 0% p=0.001, respectively). Compared with FA, patients with MC were older, and with masses being more likely to appear non-hypoechoic, not circumscribed margin, and posterior echo enhancement on US (p<0.001, p<0.001, p=0.003, respectively). Conclusion: The oval shape was the main reason for the underestimation of MCs. On US, an oval mass found in the breast of an old woman with non-hypoechoic echo, not circumscribed margin, and posterior echo enhancement was associated with an increased risk of MC, and active biopsy should be recommended.