[-Infarction or chondroma?-].

The discovery of an image of central bone calcification raises the differential diagnosis of bone infarction and chondroma. The matrix of chondroma is characteristic of cartilage. It produces typical cartilaginous calcifications: rings, arcs, coarse, irregular grains, moth-eaten appearance. These calcifications are predominantly observed in the centre of the image. They are situated in a bone defect, often multilocular, sometimes accompanied by multiple scratch marks of the cortical endosteum. In contrast, infarction is characterized by the presence of a serpiginous calcified border at the interface between live bone and dead bone. In the centre, the bony trabeculae are still visible on CT sections, in contrast with chondroma. On MRI, chondromas present a heterogeneous lobular appearance on T2-weighted sequences (checkerboard appearance) due to alternating zones of high signal intensity cartilaginous matrix and low signal intensity calcified or ossified fibrous septa. On MRI, bone infarction is characterized by a continuous peripheral line with a marked low signal intensity.