A case of undifferentiated pleomorphic sarcoma of the breast with lung and bone metastases

INTRODUCTION: Undifferentiated pleomorphic sarcoma (UPS) constitutes less than of all sarcomas in adults and rarely involves the breast. We herein present a patient with UPS of the breast with lung and bone metastases. This case was treated by eribulin as first chemotherapy, and performed mastectomy for local control. CASE PRESENTATION: A 55-year-old female presented a tumor measuring over 5 cm with pain in the right breast. Pathology of the incisional biopsy specimen led to a diagnosis of UPS. Computed tomography revealed a right tumor, right pubic tumor with osteolysis, and multiple lung metastases. She was started on eribulin; however, the tumor grew in size, indicating progressive disease, and the patient underwent simple mastectomy for local control. Pathological evaluation of the excised tumor was consistent with UPS. The patient elected palliative treatment and died due to respiratory failure caused by multiple lung metastases that exacerbated four months after surgery. DISCUSSION: Soft tissue sarcomas with distant metastases are treated with chemotherapy; however, there are currently no effective chemotherapeutic agents for UPS of the breast. Given the potential efficacy of eribulin in soft tissue tumors and the easy management of associated side effects, the patient was treated with eribulin, which however was insufficient for disease control. CONCLUSION: The prognosis of UPS with distant metastasis remains poor. Treatment approaches including chemotherapy and surgery should be considered based on the patient's general condition, prognosis, and expectations on quality of life.