Enchondroma and Ollier Disease: Cartilage Tumours Inside the Bone

An enchondroma is a benign tumour made of cartilage that grows inside a bone, within the marrow cavity. Most cause no symptoms and are found by chance on an X-ray or MRI scan taken for another reason, and they are most often seen in the small bones of the fingers. A single enchondroma usually needs nothing more than regular monitoring, and the great majority never cause problems.

When there are many enchondromas in several bones, often concentrated on one side of the body, the condition is called Ollier disease (multiple enchondromatosis). In Ollier disease the main concern is usually not the tumours themselves but the shortening and bowing they cause by disturbing bone growth. This article explains how a single enchondroma is assessed, what characterises Ollier disease and how growth problems are managed.

What is an enchondroma and where does it occur?

An enchondroma is thought to develop when some cartilage cells from the growth plate are left behind inside the bone and gradually form a small island of cartilage. Because it grows from within, it does not create a bump on the surface of the bone, which distinguishes it from an osteochondroma that grows outwards from the bone surface.

The most common sites are:

• The hand: the finger bones (phalanges) and the long bones of the palm (metacarpals); enchondroma is the most common bone tumour of the hand.
• The shoulder: the upper end of the arm bone (humerus)
• Around the knee: the lower end of the thigh bone and the upper end of the shin bone
• The foot: the toe bones and metatarsals

Cartilage tumours in areas close to the trunk, such as the pelvis, ribs and spine, are assessed with particular care. Enchondromas can occur at any age; single lesions are usually discovered in adulthood, whereas the multiple lesions of Ollier disease are noticed in childhood.

Enchondroma symptoms

Most enchondromas in the long bones cause no symptoms. An enchondroma found on an MRI scan done for shoulder or knee pain is often not the cause of that pain, which frequently comes from another problem in the joint, such as a tendon or meniscus injury. In the hand, however, the lesion can thin the outer shell of the bone, so finger swelling, thickening or a pathological fracture after a minor knock may be the first sign.

Diagnosing an enchondroma: what do X-ray and MRI show?

The first test is usually a plain X-ray. An enchondroma appears as a well-defined darker area inside the bone, often containing ring-and-arc or popcorn-like calcifications. In the hand the lesion may slightly expand the bone and thin its shell. MRI shows the size of the lesion, its internal structure and its relationship to the bone's outer layer, while CT shows the calcification pattern and any thinning of the shell in more detail.

Why does telling it apart from an atypical cartilaginous tumour matter?

For cartilage tumours in the long bones, the key question is whether the lesion is a simple enchondroma or an atypical cartilaginous tumour, a low-grade cartilage tumour previously called grade 1 chondrosarcoma. The following findings may call for further assessment:

• Marked erosion of the inner surface of the bone's shell, or a break in the shell
• A reaction of the bone's outer membrane, or a soft tissue mass extending beyond the bone
• Growth of the lesion after growth has finished
• Bone pain at rest or at night that cannot be explained by another cause
• A large lesion in a long bone, or one located close to the trunk

Grading cartilage tumours from a biopsy is not always straightforward, so imaging, symptoms and, where needed, a biopsy are interpreted together. If a biopsy is required, it should ideally be performed by the team that will plan definitive treatment. Our bone tumours page explains this process in more detail.

Enchondroma treatment: monitoring or surgery?

An enchondroma that causes no symptoms and looks typical usually needs no treatment. X-rays or MRI scans are repeated at intervals to confirm that the lesion is not changing, and the doctor sets the frequency according to its location, size and initial appearance.

Surgery is mainly considered for:

• Lesions in the hand that have caused a fracture, or have thinned the shell enough to risk one
• Enchondromas causing pain, swelling or loss of function
• Lesions that grow during follow-up or show suspicious features on imaging

The usual procedure is to scrape the lesion out from inside the bone (curettage) and fill the cavity with bone graft or a bone substitute, adding a plate or screws if extra support is needed. When a patient presents with a fracture in the hand, the fracture is often allowed to heal first and curettage is planned afterwards, although in some cases both are done together. Recovery time depends on the bone treated and the procedure performed.

What is Ollier disease?

Ollier disease is a rare condition in which enchondromas develop in several bones; it is estimated to affect about 1 in 100,000 people. The lesions are usually noticed within the first ten years of life and tend to be concentrated on one side of the body. The condition is linked to changes in the IDH1 or IDH2 genes that arise in some cells during development before birth. Because these changes are not present in every cell of the body, the condition is not expected to be passed down in families.

Common features in children include swellings of the fingers and hand, shortening of one arm or leg, bowing at the knee and ankle, forearm deformity and fractures after minor knocks. Like multiple hereditary exostoses (MHE), Ollier disease affects growth, so the two are often confused:

We cover the wider management of rare conditions like these on our page about rare childhood limb deformities.

Maffucci syndrome

When multiple enchondromas are accompanied by soft, bluish vascular lumps (haemangiomas) in or under the skin, Maffucci syndrome is considered. It is linked to similar genetic changes and calls for closer, long-term follow-up.

Treating shortening and bowing in Ollier disease

In Ollier disease the goals are to keep leg lengths balanced, to keep the joints well aligned as the child grows and to preserve hand function. Length differences and bowing can increase with growth, so treatment is rarely a one-off event; it is usually a process planned across childhood. Options include:

• Guided growth: temporarily slowing one side of a growth plate to correct angular bowing while the child is still growing
• Epiphysiodesis: stopping or slowing growth in the longer leg at the right time to reduce the length difference
• Osteotomy: cutting the bone in a controlled way and fixing it in the correct alignment
• Gradual correction and lengthening with an external fixator: using an Ilizarov-type circular frame or a computer-assisted hexapod frame to correct bowing and shortening together, little by little over days and weeks
• Hand surgery: curettage of hand lesions that impair function or cause fractures

Which method suits which age depends on the growth remaining, the expected length difference and the condition of the bone. We describe the options for leg length differences in more detail in our article on leg length discrepancy in children. Prof. Dr. Halil İbrahim Balcı's international publications focus on deformity, limb lengthening and paediatric orthopaedics, and he is co-editor of a Springer textbook on external fixator applications according to Ilizarov principles.

Risk of malignant change and long-term follow-up

Malignant change of a single enchondroma into a cartilage cancer (chondrosarcoma) is rare. In Ollier disease and Maffucci syndrome, however, the likelihood is considerably higher, and it usually arises in adulthood. Follow-up for these patients therefore does not end in childhood but continues throughout life. Because associations with certain other tumours, such as some brain and ovarian tumours, have also been reported in these conditions, follow-up is coordinated with other specialties where needed.

Changes to watch for in the long term include new or steadily increasing bone pain in adult life, growth of a lesion after growth has finished and a new swelling over a bone. Patients and families are told about these signs in advance so that they can recognise them.

When should you see a doctor?

It is advisable to see an orthopaedic surgeon if you notice any of the following:

• Unexplained swelling of a finger or hand, or a fracture after a minor knock
• Pain at rest or at night in the area of a known enchondroma
• One of your child's legs or arms looking shorter than the other
• Gradually increasing bowing of the knee, ankle or forearm
• Several swellings in the hands and feet, or soft bluish lumps in the skin
• New pain or a growing swelling in an adult with Ollier disease

Key points

• An enchondroma is a benign cartilage tumour inside the bone; most cause no symptoms and are simply monitored.
• Lesions in the hand that cause fractures or symptoms may be treated with curettage and bone grafting.
• For cartilage tumours in the long bones, imaging findings and the nature of any pain determine whether further tests are needed.
• In Ollier disease, multiple enchondromas can cause shortening and bowing, and treatment is planned throughout childhood.
• Lifelong follow-up matters in Ollier disease and Maffucci syndrome; treatment is decided individually after examination and imaging.