Incidental breast masses detected by computed tomography: are any imaging features predictive of malignancy?

To review the outcome of further assessment of breast abnormalities detected incidentally by multidetector computed tomography (MDCT) and to determine whether any MDCT imaging features were predictive of malignancy.

The outcome of 34 patients referred to the Primrose Breast Care Unit with breast abnormalities detected incidentally using MDCT was prospectively recorded. Women with a known diagnosis of breast cancer were excluded. CT imaging features and histological diagnoses were recorded and the correlation assessed using Fisher's exact test.

Of the 34 referred patients a malignant diagnosis was noted in 11 (32%). There were 10 breast malignancies (seven invasive ductal carcinomas, one invasive lobular carcinoma, two metastatic lesions) and one axillary lymphoma. CT features suggestive of breast malignancy were spiculation [6/10 (60%) versus 0/24 (0%) p=0.0002] and associated axillary lymphadenopathy [3/10 (33%) versus 0/20 (0%) p=0.030]. Conversely, a well-defined mass was suggestive of benign disease [10/24 (42%) versus 0/10 (0%); p=0.015]. Associated calcification, ill-definition, heterogeneity, size, and multiplicity of lesions were not useful discriminating CT features. There was a non-significant trend for lesions in involuted breasts to be more frequently malignant than in dense breasts [6/14 (43%) versus 4/20 (20%) p=0.11].

In the present series there was a significant rate (32%) of malignancy in patients referred to the breast clinic with CT-detected incidental breast lesions. The CT features of spiculation or axillary lymphadenopathy are strongly suggestive of malignancy.