Objective  To analyze the manifestations and characteristics of X-ray and magnetic resonance (MR) imaging of breast fibromatosis (BF).

  Methods  The materials of 15 patients with BF confirmed by surgery and pathology who undergoing digital mammography and MR examinations were analyzed retrospectively, including location of the lesion, X-ray and MR morphological features and enhancement characteristics as well as hemodynamic characteristics. The imaging features and misdiagnosis causes of BF were analyzed.

  Results  There were 17 lesions in 15 cases, including one case with bilateral onset (one lesion in each breast) and one case with 2 lesions in single breast. The median age was 31 years old. Nine cases had lesions in the breast glands, 5 cases had lesions (7 lesions in total) close to the chest wall, 1 case had the lesion in the nipple-areola complex. On X-ray images, 17 lesions were combined with structural distortion in 10 cases and 8 cases with burrs, and no calcification was seen. A total of 15 lesions showed nodules or masses in MR sequences, 14 lesions with irregular margins, 8 lesions with burrs, and 5 cases with "fascial tail sign". All the lesions showed equal or slightly low signals in T1WI, high or mixed signals in the T2WI, slightly high or high signals on diffusion weighted image (DWI), the average apparent diffusion coefficient (ADC)>1.25×10^-3 mm²/s. After enhancement, the time-signal intensity curve (TIC) curves were type Ⅰ (ascending type) and type Ⅱ (platform).

  Conclusion  BF occurring in glands is featured with mass-like manifestation, and if superficial and deep fascia tissue are involved, the X-ray is more complicated with structural distortion and burr, which is easy to be misdiagnosed asmalignant lesions. The MR shows irregular mass, and "fascial tail sign" is commonly seen. ADC value and dynamic enhancement TIC curve indicate benign lesions, which is helpful for definite diagnosis.