A 31-year-old woman presented with painful swelling in the right parav
ertebral region that had been present for 2 years. Radiography and CT
revealed an area of increased density due to multiple calcifications l
ocalized at the fourth lumbar vertebra. Histological examination revea
led that the lesion consisted of nodules of hyaline cartilage, with fo
cal areas of calcification, growing within synovial tissue.