(P 87) ANGIOSARCOMA OF THE ILIUM TREATED WITH HEMIPELVECTOMY AND HIP TRANSPOSITION FOLLOWED BY POSTOPERATIVE CHEMOTHERAPY WITH PAZOPANIB: A CASE REPORT

Objective: Primary angiosarcoma of bone is an extremely rare tumor, accounting for less than 1% of all malignant bone tumors, and cases in the pelvis represent only 15% of these tumors. Therefore, evidence regarding the efficacy of chemotherapy for advanced bone angiosarcoma is limited, and it is difficult to maintain progression-free disease. On the other hand, hip transposition has emerged as an alternative surgical technique for the reconstruction of the hip joint after hemipelvectomy. The objective of this study is to report a case of bone angiosarcoma with metastases, showing two years of survival. The treatment involved a hemipelvectomy and hip transposition using the Leeds-Keio (L-K) artificial ligament, followed by postoperative chemotherapy with pazopanib.

Methods: A case: A 69-year-old man presented with a history of right hip pain lasting for 18 months. Radiological findings indicated a pelvic tumor-like lesion, prompting the patient's referral to our hospital. He complained of hip pain and gait disturbance. The plain X-ray showed a lytic bone defect in the right iliac bone. CT image revealed destruction of the bony cortex of the ilium and a large mass extending beyond the ilium and into retroperitoneal space. CT angiography depicted rich feeding arteries of the tumor. On MRI, T1-weighted image revealed a heterogeneous mass with areas of low and partially high signal intensity, while the T2-weighted image showed high signal intensity. PET-CT revealed multiple uptakes indicative of bone metastases in the bilateral humerus, left clavicle, right scapula, mandible, lumbar spine, sacral vertebrae, and ilium. However, no obvious lesion was observed other than bone. A CT-guided bone biopsy was performed, and the pathological diagnosis was a vascular malignant tumor. He complained of intractable right hip pain and was unable to walk. Due to the difficulty in pain control, surgical intervention for the iliac lesion was considered. Preoperatively, tumor embolization was performed to control bleeding. The tumor was excised, including the pubic bone, acetabular bone and sacroiliac joint with the iliopsoas muscle and the femoral nerve. After tumor resection, hip transposition was performed, in which bone tunnels were created in the femoral head and sacrum, respectively, and they were connected using the L-K artificial ligament. The pathological diagnosis was angiosarcoma.

Results: After surgery, the patient experienced pain relief in the hip joint and became able to walk with full weight bearing 8 weeks later. Postoperative chemotherapy was performed for multiple bone metastases. Because the patient could not visit the hospital frequently, pazopanib was administered 10 weeks after surgery. Ten months after surgery, the patient complained of right hip pain and MRI identified local recurrence around the right femur, which was treated with radiation therapy. Two years after surgery, brain and lung metastases developed, and the patient died of the disease 2 years and 2 months after surgery.

Conclusion: In this case of pelvic angiosarcoma, hemipelvectomy and hip transposition using an artificial ligament proved effective for restoring ambulatory ability. The survival period of M1 patients with angiosarcoma of bone was reported almost shorter than 1 year. Reported adjuvant regimens for them included paclitaxel, doxorubicin-ifosfamide, gemcitabine, etc. However, the efficacy of pazopanib, which has been reported only in advanced soft tissue angiosarcoma, remains uncertain for angiosarcoma of bone. In our case, the metastases were controlled for over 2 years after postoperative pazopanib administration. This suggested that pazopanib may be effective to bone angiogenic sarcoma.