An uncommon cause of anterior knee pain: patellar chondroma.

A 16-year-old boy presented with a patellar mass and anterior knee pain without any trauma. On physical and radiologic assessment, a mass at the superolateral edge of the patella and a hyperintense lesion on T2 sequences of magnetic resonance imaging was detected. Excisional biopsy revealed a chondroma of patella. Primary bone tumors of the patella are extremely rare and occurence of chondroma in this localization is very uncommon. Although anterior knee pain is a very frequent and usually harmless, it is essential to consider the more severe disorders such as bone tumors.