Nonspecific inflammatory monoarthritis in the vicinity of bony metastases.

We describe a patient that presented with arthritis of a knee joint unresponsive to conventional treatment and who was found to have bony metastases of the distal femur from lung carcinoma. The presence of malignant cells could not be demonstrated in the synovial fluid or in the synovium. Our case illustrates the fact that malignant metastatic deposits in bone adjacent to a joint may cause a nonspecific synovial inflammation.