Diffuse unilateral MRI breast entities

Many benign and malignant breast entities can present with diffuse unilateral magnetic resonance imaging (MRI) findings. The unilateral breast findings can be broken down into three broad categories including asymmetric diffuse masses/non-mass enhancement (NME), diffuse unilateral skin thickening, and diffuse asymmetric background enhancement. Although correlation with clinical history is always necessary, biopsy is often needed to make a definitive diagnosis. There are some findings on MRI which can help narrow the differential including morphology, distribution, T2W signal, enhancement kinetics, and associated skin thickening. Malignant entities which will be discussed in this review include ductal carcinoma in situ, invasive ductal carcinoma, invasive lobular carcinoma, Paget disease, inflammatory breast cancer, and locally advanced breast cancer. Benign entities which will be discussed in this review include idiopathic granulomatous mastitis (IGM), infectious mastitis, pseudoangiomatous stromal hyperplasia, giant fibroadenoma, early and late radiation changes, unilateral breast feeding, and central venous obstruction, all which have varied MRI appearances. It is important for radiologists to be familiar with the common entities that can present with diffuse asymmetric unilateral MRI breast findings to ensure the correct diagnosis and management is undertaken.