Chondromyxoid Fibroma-Like Osteosarcoma in Thoracic Spine with Azygos Tumor Thrombosis, A Case Report

Abstract Background: Chondromyxoid fibroma-like osteosarcoma (CMF-OS) is extremely rare subtype of osteosarcoma, its clinical data is scarce, understanding of it is far from enough. Besides, it is short of typical imaging manifestations, it is not uncommon to be misdiagnosed clinically. Meantime 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 spine, coincidently, azygos vein thrombosis was found. A young male patient came to our clinic because of continuous back pain, then neoplastic lesion was suspected in thoracolumbar vertebrae. The pathological results of the biopsy showed low grad 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 intervened, unfortunately, he died of heart failure caused by the thrombus migrated from azygos vein to right atrium. Before the palliative decompression surgery, both the patient and the clinical team were trapped in the dilemma of how big surgery should be done to maximize the benefits of this patient. Conclusions: CMF-OS is indeed more aggressive than its pathological sections look like. Guidelines for osteosarcoma should be followed. Besides, it is important to recognize the danger of tumor thrombosis in azygos vein. Preventive measures have to be done timely to avoid catastrophic results.