Abstract
INTRODUCTION: Low-grade fibromyxoid sarcoma is an uncommon deep-seated soft-tissue sarcoma that occurs rarely in young adults and children. Although surgical resection provides a long-term prognosis, late local recurrence and metastasis may occur. CASE PRESENTATION: A 44-year-old woman with no prior medical history presented with breathing and abdominal discomfort. Contrast-enhanced computed tomography scan revealed a retroperitoneal tumor protruding into the thoracic cavity and pleural effusion on the left side. Tumor biopsy revealed sarcoma. We performed complete resection of the tumor along with part of the diaphragm and replaced the diaphragm with a prosthetic patch. Histopathologic findings indicated low-grade fibromyxoid sarcoma. The patient experienced no postoperative complications and received no adjuvant therapy. Furthermore, she survived 4 years after surgery without recurrence. CONCLUSION: Complete surgical resection is effective for low-grade fibromyxoid sarcoma; therefore, it is important to plan appropriately for complete resection when biopsy reveals malignant findings.