Bilaterally symmetrical ganglion and subchondral cysts of the knee: a case report.

A 49-year-old patient, with a maternal history of arthritis, presented with an extra-capsular lump of the left knee. Following magnetic resonance imaging (MRI) scan and excision biopsy, the lump proved to be a benign ganglion cyst. The scan had also shown focal subchondral cyst formation and articular cartilage wear in the medial femoral condyle and patella, with no other abnormality.