This is a type of non-cancerous bone tumour that comes from cartilage. Usually, the bones involved are the small bones of the hands and feet, though the condition may also involve other bones (such as the femur or tibia). It can affect an individual at any age, but is most common in adulthood. Males and females are affected equally. 

An enchondroma may occur as a single or several tumours. Multiple lesions occur with:

Ollier disease (enchondromatosis)
This frequently affects the small bones in the hands and toes (phalanges) and the metatarsals (the long bones behind the phalanges).

Maffucci's Syndrome 
An extremely rare condition that combines multiple enchondromas with benign soft tissue tumours (called hemangiomas). Maffucci’s Syndrome tends to appear in the hands and feet, and is more likely to be malignant than Ollier's Disease.

Because they are painless, most enchondromas are only discovered when X-rays are taken for another reason. Usually, enchondromas need no treatment, though they can be aggressive and require further attention – usually in the form of surgery.