Monoarthritis secondary to joint metastasis. Two case reports and literature review.

Synovial metastases from neoplasms are uncommon. We report two cases of knee monoarthritis due to joint metastasis. Joint fluid cytology established the diagnosis. In one patient, an epidermoid carcinoma of the ureter metastasized to the left knee. The other patient had chronic monoarthritis of the left knee unresponsive to conventional treatment and was found to have distal femoral metastases from a lung adenocarcinoma. Only 28 cases of synovial metastases from solid tumors have been reported in the literature. The knee is the most common target, the lung the most common site of the primary (12 cases), and adenocarcinoma the most common histological type (12 cases). Joint metastasis carries a poor prognosis with a mean survival of less than 5 months.