Objective:To investigate the characteristic of mammography, magnetic resonance imaging (MRI), ultrasonography and pathology of mucinous breast carcinoma (MBC); and to study the differential diagnosis value of the three methods in pure MBC (PMBC) and mixed MBC (MMBC).Methods:One hundred and three lesions in 100 MBC patients confirmed by surgery and pathology in the Affiliated Cancer Hospital of Fudan University from January 2011 to January 2018 were retrospectively analyzed. According to the 2013 version of the breast imaging report and data system (BI-RADS) criteria, the three imaging findings of lesions were described, evaluated and classified. According to pathological results the lesions were divided into two groups, PMBC and MMBC, and their imaging features and differences were analyzed.Results:On mammography, most of the mammary glands were c-types (55/76, 72%), and the lesions were mostly masses (71/76, 93%), most of which were round, oval, high-density masses with circumscribed, microlobulated or indistinct margins. Suspected malignant calcification was showed in 21% (16/76) of these lesions. Eight patients had ipsilateral axillary lymphadenopathy. On MRI, most lesions showed masses (69/72, 96%). Sixty-seven lesions (31/72, 43%; 36/72, 50%) showed equal and high signals on T 1WI, and 54 lesions (54/72, 75%) showed higher signals on T 2WI. The margins were mostly irregular and burrs (53/69, 77%). Masses enhancement was dominated by heterogeneous enhancement (32/69, 46%) and rim enhancement (33/69, 48%). The patter of time-signal intensity was dominated by progressive curves (41/72, 57%) and platform curves (24/72, 33%). The lesions had heterogeneous high signal on DWI. The ADC signal was slightly higher than normal gland. Seven patients were accompanied with thickening of the skin and nipple retraction. Eight patients had ipsilateral axillary lymphadenopathy. One patient had multiple lung metastases. On ultrasonography, most lesions showed irregular masses, heterogeneous hypoechoic, well-defined margins, posterior echo enhancement (75/97, 77%). Color Doppler imaging showed vascularity in 65% (63/97) of these lesions. Nine patients had ipsilateral axillary lymphadenopathy. There was significant difference in margins between PMBC and MMBC ( P < 0.05) on MRI and ultrasonography. It showed significant difference in vascularity between 2 groups ( P < 0.05) on MRI. Conclusions:MBC has some typical features in mammography, MRI and ultrasonography. Realizing its features can improve the diagnostic accuracy of MBC, and it also can contribute to the differential diagnosis of PMBC and MMBC.