Chest wall mass in a 50-year-old woman.

A 50-year-old postmenopausal woman presented with a 9month history of a lump on her left anterior chest wall in the region of the 2nd and 3rd costochondral junction. She reported the mass changed in size and at times felt soft and fluctuant. It intermittently swelled, causing her local discomfort followed by periods of spontaneous regression, which would be accompanied by inflammation localized to the surrounding chest wall. Physical examination revealed a firm mass along the left superior chest wall measuring approximately 6 9 3 cm. It was fixed in position and slightly tender to palpation. She was afebrile. No other joint complaints were reported. She had a history of ovarian cancer diagnosed at age 24 years; the workup for metastatic disease to the bones and solid organs was negative at that time. Her ovarian cancer was treated with whole-abdomen radiation therapy, chemotherapy, and a total abdominal hysterectomy and bilateral salpingooophorectomy. She had no symptoms or signs of metastatic disease in the interim. Plain radiographs of the chest were noncontributory. CT and MRI of the chest wall were performed (Figs. 1, 2). Based on the history, physical examination, and imaging studies, what is the differential diagnosis?