An enchondroma is a type of benign (non-cancerous) bone tumor that originates from cartilage. Cartilage is the specialized, gristly connective tissue that is present in adults and the tissue from which most bones develop. Cartilage plays an important role in the growth process. There are many different types of cartilage that are present throughout the body. An enchondroma most often affects the cartilage that lines the inside of the bones. The bones most often involved with this
benign tumor are the miniature long bones of the hands and feet. It may, however, also involve other bones such as the femur (thighbone), humerus (upper arm bone), or tibia (one of the two lower leg bones).
Enchondromas are the most common type of hand tumor. While it may affect an individual at any age, it is most common between the ages of 10 and 20 years. The occurrence between males and females is equal. There is a syndrome called Ollier's Disease in which patients have many enchondromas. These must be carefully monitored as there is about a 30% risk of these patients developing a malignant form of the enchondroma called a chondrosarcoma. While the exact cause of enchondroma is not known, it is believed to occur either as an overgrowth of the cartilage that lines the ends of the bones, or as a persistent growth of original, embryonic cartilage.
Individuals with an enchondroma often have no symptoms at all. The following are the most common symptoms of an enchondroma. However, each individual may experience symptoms differently. Enchondromas are slow growing, clinically benign tumors composed of mature hyaline cartilage. Most are incidentally discovered at an early age (10-30 years) as a palpable bony nodule. Males and females are equally affected. Infrequently they are symptomatic, causing soft tissue swelling and, less likely, pain at the lesion site. Pain can be a sign of pathologic fracture or malignant transformation. No treatment is required for asymptomatic lesions. If fracture occurs, as in this patient, it is usually treated with curretage and bone grafting. A small percentage of enchondromas will undergo malignant transformation. This is usually a slow process, occurring over decades. It is more common in long bones than short.
Treatment may include surgery (in some cases, when bone weakening is present or fractures occur) and bone grafting - a surgical procedure in which healthy bone is transplanted from another part of the patient's body into the affected area. If there is no sign of bone weakening or growth of the tumor, observation only may be suggested. However, follow-up with repeat x-rays may be necessary. Some types of enchondromas can develop into malignant, or cancerous, bone tumors later. Careful follow-up with a physician may be recommended.