摘要
An elderly woman with rheumatoid arthritis and receiving nonsteroidal anti-inflammatory drugs (NSAIDs) treatment was diagnosed with a malignant fibrous histiocytoma in her left knee joint. However, no metastatic lesion caused by the malignant fibrous histiocytoma was found, probably owing to the NSAIDs therapy. Her general condition worsened, and eventually led to renal failure and death from progressive respiratory failure caused by pulmonary effusion. This is the first known report of a malignant fibrous histiocytoma originating in the left knee joint that was complicated by rheumatoid arthritis.