Imaging findings in mucinous breast carcinoma and correlating factors

To investigate the factors influencing mammographic and sonographic features of mucinous breast carcinoma.

Forty-six patients diagnosed as mucinous breast carcinoma between March 2005 and April 2009 were studied. Mammographies of all patients and sonographies of 41 patients were analyzed retrospectively. Microscopic slides were re-evaluated by a pathologist in order to estimate the volume of extracellular mucus which was classified as: (+), less than 50% of mucus; (++), 50-80% of mucus; and (+++), more than 80% of mucus.

Thirty-one (61.3%) cases of pure mucinous type and 2 (33.3%) of mixed mucinous carcinoma presented as masses had well-defined margins on mammography. No correlation was found between margin characteristics and histological type as well as extracellular mucus rates. Denser breasts and young age group had significantly higher ratios of tumors presented with ill-defined masses than its counterpart. Sonographically, 100% lesions showed a hypoechoic lesion, 76.5% lesions in pure type and 71.4% lesions in mixed type showed a heterogeneous internal echo. No correlation was found between sonographic findings and histological type as well as extracellular mucus rates. Lesions with >40 positivity PCNA had higher ratio presented as ill-defined margins than those of ≤40% positivity PCNA.

The most common appearance of mucinous breast carcinoma is a mass on mammography and a hypoechoic lesion with heterogeneous internal echo on sonography. Mammographic margins and sonographic findings have no relation with histological type and extracellular mucus rate. Mammographic margin features are correlated with breast density and age and PCNA.