MRI manifestations of sclerosing adenosis of the breast: a single institution experience

Purpose: Sclerosing adenosis (SA) of the breast is a benign proliferative lesion that may mimic malignancy on imaging. We present the magnetic resonance imaging (MRI) features of 26 patients with breast adenosis. Material and Methods: Within a 2-year search of our PACS system, we identified breast MRI examinations of 26 female patients (age: 46 years, mean age: 35-70 years) with histological proof of SA. All patients were initially classified as BI-RADS category 4 on MRI. Four out of 26 patients had SA and fibrocystic changes or other benign pathologies while 22/26 patients were diagnosed with pure adenosis. One patient had coexisting in situ intraductal cancer. The MRI morphologic features and enhancement characteristics of mass-like adenosis as well as the morphology, distribution and enhancement pattern of non-mass enhanced (NME) SA lesions were retrospectively assessed by two radiologists experienced in breast imaging. Results: Eighteen patients presented with a palpable lesion and 8 patients had a suspicious or indeterminate finding on screening mammogram. Mass lesions were observed in 19/26 (73%) patients and 7/26 (27%) patients displayed NME patterns. The diameter of SA lesions ranged from 0.5 to 2.5 cm (mean: 1.4 cm). On dynamic contrast-enhanced MRI, time-signal intensity curve was type I in 15/26 (57.7%), and type II in 11/26 (42.3%) SA lesions. Conclusions: SA most often presents as a mass lesion with benign contrast kinetics on MRI of the breast.