Synovial metastasis of the knee in a mutant rectal adenocarcinoma patient.

Synovial metastasis is an unusual entity in solid tumours and only a few cases have been reported in the literature. We report a case of synovial metastasis of the knee in a young patient with progressive rectal adenocarcinoma and review previously published case reports of synovial involvement in advanced colorectal carcinomas. Synovial metastasis is just one of the multiple possibilities of differential diagnosis in patients with cancer suffering from monarthritis. Radiological tests (plain radiographs, bone scans, MRI of the joint and so forth) can be unspecific and cytological examination of the synovial fluid and/or histology of synovial biopsies is essential for a definitive diagnosis so as to tailor the best treatment for patients. Given the poor prognosis associated with these intra-articular secondaries, treatment is often limited to palliation.