Malignant transformation is less often seen in solitary exostosis which, although microscopically similar and much more common than multiple exostosis, does not have an hereditary basis and is not a systemic disorder of skeletal development. General Considerations E nchondromatosis is a rare disorder of skeletal development characterized by the presence of multiple circumscribed foci or masses of cartilage in the interior of bones preformed in cartilage, particularly the long and short tubular bones of the extremities. The disorder does not appear to be hereditary. Clinical manifestations of the condition may first appear in early childhood. Swellings of the fingers and toes, bone deformities, leg length discrepancies, and pathological fractures may be caused by the presence of the enchondromas.
Skeletal involvement tends to be greater on one side of the body than the other.
Microscopically, the multiple enchondromas are composed of lobules of cartilage cells of benign but richly cellular appearance and forming a hyaline matrix. Solitary enchondroma, femur, composed of lobules of benign cartilage cells and hyaline matrix.