Extraskeletal Intramuscular Chondroma of the Knee - Case Report and Review of the Literature.

Extraskeletal chondromas are small nodular cartilaginous lesions not attached to bone or the periosteum. They are rare tumors commonly occurring in the hands and feet. The objective of the present study is to describe a case of extraskeletal intramuscular chondroma (EIC) in the left knee and the diagnostic challenges faced by us. A 25-year-old female patient presented with slow-growing swelling in the left knee for 2 years. Clinically, the swelling was arising from the quadriceps muscle. We considered possibilities such as rhabdomyoma, neurofibroma, and intramuscular lipoma. Imaging studies suggested a benign fatty tumor. She was treated by excision. Microscopy was consistent with EIC without recurrence. A rare entity, clinically, EIC can mimic other benign soft-tissue tumors. Histopathology exams can provide a definitive diagnosis. The excision of the tumor is curative.