Monoarthritis of the elbow due to metastatic colon carcinoma: diagnosis based on the presence of adenocarcinoma cells in synovial fluid.

There are many diseases that can cause monoarthritis, malignancy being one of the more rare causes. We present such a case and discuss the relationship between malignancy and arthritis. Typically a large joint is involved, most frequently the knee and very rarely the elbow. The value of cytological examination of synovial fluid is stressed. Synovial fluid in malignant joint disease is usually sanguineous and not consistent with an inflammatory process. Synovial fluid analysis can avoid a biopsy of bone or synovium and lead to an early diagnosis and palliative treatment.