A, Anteroposterior view of pelvis of a 78-year-old man reveals a large tumor arising from the pubis with soft-tissue extension. The mass has punctate calcification consistent with a chondrosarcoma. Although plain radiography is more helpful for determining the diagnosis, MRI (B and C) better defines the extent of the soft-tissue mass and its relationship to adjacent anatomic structures. D, Typical microscopic appearance of conventional chondrosarcoma.