Maffucci's syndrome combined with dedifferentiated chondrosarcoma.

We report a rare case of Maffucci's syndrome combined with dedifferentiated chondrosarcoma in the right shoulder girdle developing from pre-existing enchondroma. In this case, magnetic resonance imaging was useful in diagnosing dedifferentiated chondrosarcoma before surgery. T2-weighted imaging was used to distinguish between the cartilaginous component and the dedifferentiated one. Histologically, there was enchondroma in the humerus and grade 2 chondrosarcoma in the scapula. Further, the dedifferentiated tumor had three mesenchymal elements: osteosarcoma, malignant fibrous histiocytoma, and fibrosarcoma. This histological heterogenicity may be due to mesodermal dysplasia of Maffucci's syndrome.