A giant cell rich osteosarcoma of the proximal ulnar bone treated by elbow arthroplasty: A case report

INTRODUCTION: Osteosarcoma is a malignant tumor of the bone. The treatment and prognosis have changed dramatically these days. Limb salvage surgery is a widely accepted alternative to amputation in patients with sarcoma. In most cases, the diagnosis of osteosarcoma is not difficult. We reported a rare location and a rare type of osteosarcoma case treated by elbow arthroplasty along with the challenging diagnostic and treatment. CASE PRESENTATION: We reported 46 years old female complained of pain on her left elbow for 5 months. An x-ray showed lytic lesion on the medial side of the elbow while the MRI examination suggested a malignant bone tumor in the epi-meta-diaphyseal of left ulnar bone. Core biopsy showed a Giant Cell containing lesion. The histology of resected tumor and Ki67 staining confirmed the diagnosis of giant cell-rich type osteosarcoma. DISCUSSION: Giant cell rich osteosarcoma is an uncommon variant of osteosarcoma which characterized by an abundance of osteoclastic giant cells and lack of tumor osteoid. Involvement of forearm in conventional osteosarcoma is extremely rare. This was the epidemiologic reason why the osteosarcoma was not the first diagnosis of our case. Being a very rare location of the osteosarcoma, the management poses a special challenge. They are the surgical technique, which is not well described, and the implant that need to be custom made. CONCLUSION: Giant cell rich osteosarcoma is difficult to diagnose because its histology and radiologic feature mimic a benign giant cell tumor.