Recurrent malignant melanoma presenting as monoarthritis.

A 29-year-old woman had surgery for a level IV malignant melanoma of the right calf. After a disease-free interval of almost 4 years, she presented with right knee arthritis that proved to be due to recurrent melanoma in the femoral condyle. Metastatic carcinomatous arthropathy should be considered in the differential diagnosis of monoarthritis.