To investigate dinical, image features and histopathology of breast mucinous carcinoma in order to improve the early diagnosis of breast mucinous carcinoma.

From January 2008 to December 2011, twenty-one patients with 22 focuses mucinous carcinomas of the breast who were confirmed by pathology were included in this study. Mammogram and sonographic features were retrospectively evaluated according to the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) Lexicon, all cases were classified by BI-RADS. Histological types of breast mucinous carcinoma included two forms, mixed and pure type. The latter was classified into cellular variants and hypocellular variants. The correlation between the mammogram and ultrasonographic findings of mucinous carcinoma and histologic features in different types were analyzed.

Histological types of breast mucinous carcinoma included 8 mixed type and 14 pure type (6 cellular variants and 8 hypocellular variants). The clinical manifestation were as follow, 81.8%(18/22) of cases presented mass as main complains, only 3 cases complained of calcification by mammogram during routine breast carcinoma screening. About ultrasonography examination, all 21 cases presented as solid mass. In pure form, they showed well-defined margins with no pseudocapsule and isoechogenic or hypoechoic internal echo pattern relative to that of subcutaneous fat in 85.7% (12/14) focuses which histological type were pure type. Ninety-two point nine percent of pure type focuses had posterior enhancement. Seventy-five percent (6/8)of mixed type focuses and 14.3%(2/14) of pure type focuses, however, demonstrated ill-defined and or spiculated margins with hypoechogenic structure. Sixty-three point six (14/22) percent of cases being classified as BI-RADS 4 or 5 were suspected as malignancy by ultrasonography and Mammograms respectively. These mammograms features contained 10 masses, 2 focal asymmetrys, one architectural distortions with malignant clacification and one isolated indifferent clacification. Mammographic main appearances of mass were well-defined margins with microlobulation for pure type, poorly differentiated or spiculated margins for mixed type. Eighty-one point eight (18/22) percent of focuses were suspected as malignancy by one kind of imaging, mammography or ultrasonography. Forty-five point five (10/22) percent of focuses were suspected as malignancy by both mammogram and ultrasonography, which suggested as BI-RADS 4 or 5.

Palpable mass was the main clinical manifestation of breast mucinous carcinoma. Breast mucinous carcinoma, especially pure type, did not have the typical image features for benign or malignant breast masses, which maybe be diagnosed benign focuses by mammography and or ultrasonography. Margins of the masses were the very important for differentiating begin or malignant. Mixed type of breast mucinous carcinomas tumors have more aggressive margin imaging characteristics, which demonstrated ill-defined and or spiculated margins. It is suggested that the combination of mammogram with ultrasonography to avoid the delay diagnosis of breast mucinous carcinoma. Biopsies should be performed when malignancy was suspected by any one of mammogram and ultrasonography.