Steadman, LarynCrook, Susan2019-04-302019-04-302018-09-13Steadman, L., & Crook, S. (2018). Fibromatosis arising from the pectoralis major muscle mimicking breast cancer. Radiology case reports, 13(6), 1174–1178. doi:10.1016/j.radcr.2018.08.017https://hdl.handle.net/1805/19021Fibromatoses are soft tissue tumors composed of fibroblasts which commonly appear in the muscular aponeurosis of the abdomen. Mammary fibromatoses occur in only 0.2% of breast neoplasms and have been reported in association with prior breast augmentation and Gardner's syndrome. Multiple imaging modalities have been used to characterize the appearance of breast fibromatosis; however, it remains a tissue diagnosis given the variability both within and across modalities. We present the case of a 25-year-old female with a history of palpable breast mass who was evaluated with ultrasound, diagnostic mammography, MRI, and CT. Ultrasound-guided biopsy revealed fibromatosis, and MRI ultimately revealed that the mass was arising from the pectoralis major muscle and extensively involved the chest wall.en-USAttribution-NonCommercial-NoDerivs 3.0 United StatesFibromatosisMammary fibromatosisChest wallPectoralisArticle