Objecitve To investigate the ultrasonographic features of pure mucinous carcinoma of the breast（PMBC）.Methods A total of 27 cases of PMBC included 20 conventional pure mucinous breast carcinomas without micropapillary architecture（cPMBC） and 7 mutinous carcinomas with micropapillary pattern（MUMPC） confirmed by operation were retrospectively analyzed.The ultrasound scores and blood flow scores of cPMBC and MUMPC with different clinicopathological characteristics were summarized.Results Twenty-three cases of PMBCs were hypoechoic

4 cases were complex echogenicity.13 cases were irregular

3 cases were indistinct

10 cases were microlobulated

5 cases were angular

5 cases with microcalcification.The ultrasound scores of cPMBC and MUMPC

different molecular types or clinical stages were less than 5.5 points（96.6%）.The blood flow scores of most of cPMBC were 1 point（60.0%） and MUMPC were 0 point（71.4%）.Conclusion The ultrasonic characteristics of PMBC are not typical

and the sonographer should pay more attention to observe the shape and margin for the lesions

and be alert to irregular shapes

non-circumscribed margins and microcalcifications of the masses to reduce misdiagnosis.