Ollier’s disease, or enchondromatosis, is a rare congenital disease of abnormal bone development due to cartilage overgrowth in the form of enchondromas, or benign, non-cancerous tumors. The limbs’ long bones and joint cartilage are affected by the disease, and the small bones and metatarsals of the hands and feet are common sites for the enchondromas to develop. The masses can also grow elsewhere in the body.

It is possible but not common for the tumors to become malignant, or cancerous. Most cases of Ollier’s disease remain benign and do not require treatment, unless bone tissue is destroyed by quick-growing tumors. Then, the growths can be surgically removed.