The distribution of fibroglandular tissue in the breast is often symmetrical. Changes in that symmetry may indicate a hidden lesion in the parenchyma. The evaluation of asymmetric densities in the breast is one of the main day-to-day challenges for radiologists, i.e., differentiating normal superimposed structures from true parenchymal lesions. The knowledge of different techniques and resources used to investigate asymmetric densities as well as evaluation protocols are essential to establish the nature of the lesions. Asymmetric densities may be the only sign of breast cancer otherwise clinically and radiologically concealed.

Keywords: Asymmetric density, Mammography, Invasive lobular carcinoma