[Patelar metastasis of primary lung cancer].

Patellar metastasis is uncommon. The clinical presentation is often misleading, suggestive of septic arthritis or meniscal disorder after knee trauma. We report the case of a 71-year-old patient who developed knee pain aggravated by movement with pseudo-blockage which was found to be related to a secondary localization of a primary lung cancer. Low blood flow in the patella probably explains why patellar metastasis is so rare.