<prompt> Enchondroma commonly arises fromRibsVeretebreTibiaPhalanges  <response>: ENCHONDROMA Rarely an enchondroma may extend through the coex and demonstrate a exophytic growth pattern. This is known as an enchondroma protuberans, and may either be seen sporadically or as pa of Oilier disease. Almost all enchondromas are located in the medullary cavity of tubular bones. Dds: bone infarct , chondrosarcoma, intraosseous other benign Ivtic bone lesions, metastases granulomatous disease : sarcoidosis, tuberculosis X-ray CT Typically enchondromas are small 1 - 2cm lytic lesions with non-aggressive features. narrow zone of transition sharply defined scalloped margins : may have mild endosteal scalloping expansion of the overlying coex may be present but there should not be coical breakthrough unless fractured Chondroid calcifications may be present : rings and arcs calcification-STIPPLEDPUNCTATEPOPCORN no periosteal reaction The majority of enchondromas more frequ the metaphyseal region entirely arise in A cailaginous lesion in an epiphysis is more likely to be a chondrosarcoma . Refer Apleys 9the p 197 