The mechanisms by which chondromas develop are not yet fully understood. It would appear that, in the vast majority of cases, the manifestations of the disease stabilize with puberty, after the end of growth.

However, in adulthood, there may be a risk of cellular modification of the chondroma, which may, for example, change in volume. Some of these chondromas, depending on where they are implanted in the skeleton, can aggravate deformities. In such cases, surgery may be required in adulthood.

A risk of progression to chondrosarcoma is possible. Chondrosarcoma is a malignant tumor defined by the absence of bone formation associated with tumoral cartilage elements. Chondrosarcomas present multiple histological forms with very different evolution, prognosis and treatment.

Statistics showing a 30-50% transformation rate from chondromas to chondrosarcomas are presented on other websites. These statistics are based on samples that are too small to be representative, and do not include patients who could not be identified. Some disease specialists, without denying the risk, put the figures at between 1% and 5%. This corroborates the association’s findings, since a figure of 4% of patients affected by chondrosarcoma was calculated on the basis of the association’s members.

It would appear that the risk is higher for people with Maffucci. However, once again, there are no scientific studies to support this finding. Malignant changes generally occur in adults after the age of forty. On rare occasions, they have been observed in children. It is advisable to seek medical advice if certain symptoms appear (pain, increase in volume, sensation of heat in the chondromas).