A Case of Dedifferentiated Liposarcoma of the Chest Wall

Abstract

A 68-year-old woman, who had been aware of a right breast tumor mass for eight years, was referred to our department because of gradual enlargement of the tumor. Magnetic resonance imaging (MRI) showed a bulky tumor measuring approximately 17 cm in the right breast with mostly fatty signals, and it contained a solid mass measuring approximately 8 cm. The mass showed a beak sign between the mass and the pectoralis major muscle, indicating that the tumor originated from the chest wall. Histological examination of the solid mass suggested a non-epithelial malignant tumor, and immunostaining was MDM2(+) and CDK4(+). No distant metastasis was found, and the patient was diagnosed as dedifferentiated liposarcoma of the pectoralis major muscle. A right mastectomy and dissection of the pectoralis major and minor muscles were performed with a preoperative diagnosis of dedifferentiated liposarcoma of the pectoralis major muscle. Pathological examination showed that the tumor was contiguous with the pectoralis major muscle, and a grayish-white nodule measuring 7 cm was located inside the adipose tissue tumor measuring 17 cm. The patient was diagnosed as having dedifferentiated liposarcoma arising from well-differentiated liposarcoma. No recurrence has been observed for twenty months after surgery.