An enchondroma is a benign (non-cancerous) tumor that is formed from cartilage cells that line the inside of the bones. These cells would normally form bone but for some unidentified reason they don’t, instead they become a small tumor. Enchondromas are one of the most common benign bone tumors, and usually occur in the small bones of the hands and feet but can affect other bones like the thigh bone (femur), the upper arm (humerus) and shin bone (tibia).
Enchondromas are active in kids, meaning that they are growing largely due to the fact that kids are growing. They are usually diagnosed from age 10 – 20 but they remain present in adulthood and are described as “dormant” or “burned out” because they aren’t actively growing.
Enchondromas can become cancerous but this is very rare. If they do transform to a cancerous tumor it is to a chondrosarcoma. For this reason, treating physicians recommend continued watching of an enchondroma as an important part of the treatment.
Cause of Enchondroma
The reason an enchondroma forms is not known. People with Ollier’s disease and Maffucci’s syndrome may develop many enchondroma.
Symptoms of Enchondroma
Enchondromas often don’t cause any pain. They may result in swelling or enlargement of the affected bone which can be visible in the case of the hand or foot bones. They can become painful if the tumor is large or if there is a fracture in the affected bone. In syndromes where multiple enchondromas develop (Ollier’s disease or Maffucci’s syndrome) the bony deformities are usually pretty severe.
Diagnosing an Enchondroma
Because they aren’t usually painful, enchondromas are often found during a routine office visit to a physician. A patient may mention, or a physician may notice, a swelling of the affected area. An x-ray will usually show an elongated, ‘popcorn’ shaped area in the mid portion of the bone; sometimes there is a black area indicating a lytic process.
A good medical history is important to help determine if a more serious disease process is occurring. If a patient has night pain or pain at rest it could raise a suspicion for chondrosarcoma.
A biopsy is important to confirm the diagnosis of an enchondroma. Enchondromas and chondrosarcomas develop from the same type of cell so it’s necessary to be certain the tumor is not a low-grade chondrosarcoma.
Treatment of an Enchondroma
Usually enchondromas can be watched, not needing any treatment. Careful monitoring with regular x-rays is recommended to be sure a more aggressive process isn’t occurring. The treating physician may recommend surgery if there is a fracture in the area of the enchondroma or if the bone looks weakened to the point it will eventually fracture. The surgery will include curetting (scooping out) the tumor and filling the area with bone graft material and/or bone cement. There is a very small chance (~6%) 1 that the tumor will return (recur) so regular follow-up is recommended.
In cases where the biopsy tissue has the appearance of enchondroma and low-grade chondrosarcoma, the treating physicians may recommend treatment as if the tumor is a chondrosarcoma. This is a situation that should be discussed at length with a patient prior to deciding on a treatment course.
1. Verdegaal S; Brouwers H, van Zwet E, et al; Low-Grad Chondrosarcoma of Long Bones Treated with Intralesional Curettage Followed by Application of Phenol, Ethanol, and Bone-Grafting; JBJS Am; 2012:94:1201-1207