Abstract
Desmoid tumors are rarely observed tumors that develop from deep muscle and aponeurotic tissues. They are histologically intermediate, and exhibit a local aggressive course. These tumors have been observed in the abdominal region, and are rarely encountered in the thoracic wall. The most effective treatment appears to be surgery. A 59-year-old female patient was admitted with the complaint of right breast pain and a palpable mass. The patient had undergone a modified radical mastectomy surgical procedure of the right breast due to invasive breast carcinoma 10 years before. A mass with a soft tissue density and a size of 44×22 mm was detected in the thoracic computed tomography of the patient, which subsequently resulted in biopsy followed by surgery. As a result of the pathological examination of the mass, the diagnosis was determined as desmoid tumor. Due to the closeness of the tumor to the surgical margin, the patient was administered radiotherapy and maintenance imatinib treatment was started.