ABSTRACT
BACKGROUND: Extraskeletal osteosarcoma (ESOS) is a highly malignant osteosarcoma that occurs in extraskeletal tissues. It often affects the soft tissues of the limbs. ESOS is classified as primary or secondary. Here, we report a case of primary hepatic osteosarcoma in a 76-year-old male patient, which is very rare. CASE SUMMARY: Here, we report a case of primary hepatic osteosarcoma in a 76-year-old male patient. The patient had a giant cystic-solid mass in the right hepatic lobe that was evident on ultrasound and computed tomography. Postoperative pathology and immunohistochemistry of the mass, which was surgically removed, suggested fibroblastic osteosarcoma. Hepatic osteosarcoma reoccurred 48 d after surgery, resulting in significant compression and narrowing of the hepatic segment of the inferior vena cava. Consequently, the patient underwent stent implantation in the inferior vena cava and transcatheter arterial chemoembolization. Unfortunately, the patient died of multiple organ failure postoperatively. CONCLUSION: ESOS is a rare mesenchymal tumor with a short course and a high likelihood of metastasis and recurrence. The combination of surgical resection and chemotherapy may be the best treatment.