Invasive Micropapillary Carcinoma of the Breast: Mammographic, Sonographic and MR Imaging Findings

Purpose : We performed this study to investigate the characteristic imaging and clinicopathologic features of invasive micropapillary carcinoma of the breast. Materials and Methods: Among the 47 women with surgically confirmed invasive micropapillary carcinoma between 2005 and 2009, 32 patients (mean age, 50 years; range, 37-69 years) had all preoperative mammography, ultrasound (US) and MR images. Two radiologists retrospectively assessed the imaging findings, clinical presentation and histological results of the patients. Results: On mammography, 29 of 32 patients had suspicious findings. Among them, a mass (or focal asymmetry) with calcifications was the most common findings (15/32, 65%). The calcifications were noted in 20 patients (63%) and the shape of calcifications was frequently amorphous or punctate (n = 12, 60%). On US and MR imaging, all lesions had suspicious findings. The most common US findings were single (n = 20) or multiple (n = 10) irregular hypoechoic mass (es). The mass was frequently hypoechoic (n = 29, 97%). On MR imaging, the type of lesions was a mass or masses in 23 (72%), a mass combined with non-mass in six patients, and non-mass lesions in three patients. Histologically, axillary lymph nodes metastasis were very common (25/32, 78%). Asymptomatic clinical presentation was not usual (9/32, 28%). Conclusion: The imaging features of invasive micropapillary carcinomas strongly suggest malignancy. Microcalcifications on mammography, marked hypoechogenicity on US and an irregular mass, often combined with non-mass on MR are common. Axillary lymph node metastasis is commonly associated. Index words : Breast∙Carcinoma∙Invasive micropapillary carcinoma∙MR imaging∙Sonography