Abstract
Background: Chondromyxoid fibroma-like osteosarcoma (CMF-OS) is an extremely rare subtype of osteosarcoma, its clinical data are scarce, and our understanding of it is far from sufficient. As it has few typical imaging manifestations, it is not uncommonly misdiagnosed clinically. Azygos vein thrombosis is also a rare entity, and there is a big controversy over treatments for it. Case presentation: Herein, we report a case of CMF-OS that occurred in the spine, coincidently, azygos vein thrombosis was found. A young male patient came to our clinic because of continuous back pain, and a neoplastic lesion was suspected in the thoracolumbar vertebrae. The pathological results of the biopsy showed a low grade of osteosarcoma, and chondromyxoid fibroma-like osteosarcoma was the primary diagnosis. Since the tumor cannot be en-bloc resected, he received palliative decompression surgery, followed by radio and chemotherapy. Azygos vein tumor thrombosis was not treated and, unfortunately, he died of heart failure caused by the thrombus migrating from the azygos vein to the right atrium. Before the palliative decompression surgery, both the patient and the clinical team were trapped in the dilemma of how big a surgery should be carried out to maximize the benefits of this patient. Results and complications: CMF-OS is indeed more aggressive than its pathological sections suggest. Guidelines for osteosarcoma should be followed. Furthermore, it is important to recognize the danger of tumor thrombosis in the azygos vein. Preventive measures have to be performed in a timely manner to avoid catastrophic results.