Abstract
A 20-year-old man presented with a hard and painless swelling at the left chest wall. Plain radiographs showed an expansile lesion of the third rib. Most of the lesion was intramedullary located, well-defined and osteolytic, whereas the inner portion (black arrow) was partially calcified and protruding within the chest (Fig. A). The costochondral junction was not involved. Subsequent CT confirmed the eccentric location of the lesion. The inner part contained chondroid-like calcifications and showed intimate relationship with the left lung (white arrow). There was osseous expansion resulting in focal absence of the outer cortex. Sparing of a thin layer of fat adjacent to the outer cortex was indicative of absence of soft tissue extension (Fig. B). On MRI, the outer medullary part of the lesion was of high signal on T2-weighted images, in keeping with cartilaginous matrix. The exophytic inner part (white arrow) was of intermediate signal, with internal foci of low signal due to chondroid calcifications (Fig. C).