MR imaging of primary breast fibromatosis

Fibromatosis of the breast is a very rare mesenchymal neoplasm. Most of the cases reported arise from the aponeurosis or muscular fascia of the chest wall or shoulder girdle, involving the pectoralis muscle in patients with history of previous surgery (Cancer 41 (1978) 1409). We report a case of pathologically proven primary fibromatosis of the breast in a young woman, in which the neoplasm arises de novo and is not attached to the chest wall. Mammographically, it appears as a high-density spiculated mass and sonographically, it is irregular and hypoechoic. MR imaging showed that it is hyperintense on both T1- and T2-weighted images and is contrast enhancing.