Ollier disease is a rare skeletal disorder in which multiple noncancerous cartilage growths, called enchondromas, develop inside the bones. These growths form near the ends of bones where normal growth occurs, most often in the hands, feet, and long bones of the arms and legs. The condition typically becomes noticeable around age 5, and enchondromas usually stop forming once a person finishes growing in early adulthood. While the growths start out benign, they carry a meaningful risk of becoming cancerous over a person’s lifetime.
How Enchondromas Affect the Skeleton
In Ollier disease, clusters of cartilage cells that should have matured into bone instead remain as cartilage, forming tumors inside the bone itself. These enchondromas tend to appear in the metaphyses, the flared portions of bone near the growth plates, and in the shafts of tubular bones. The hands are the most commonly affected area, followed by the upper arm bone (humerus) and shinbone (tibia). Flat bones like the pelvis, as well as the ribs, skull, and spine, can also be involved.
A hallmark of Ollier disease is its asymmetric distribution. The growths predominantly cluster on one side of the body. Some people do develop enchondromas on both sides, but even then, one side is usually more heavily affected. The number, size, and location of enchondromas varies enormously from person to person. Some individuals have only a few small growths in their fingers, while others develop large, deforming masses in major limb bones.
The physical consequences depend on where and how aggressively the enchondromas grow. Common problems include painless bony lumps on the fingers and toes, limb length differences when one leg grows shorter than the other, angular bone deformities, and an increased risk of fractures through weakened bone. In milder cases, the disease may cause little more than cosmetic changes in the hands. In severe cases, it can significantly limit mobility and function.
What Causes It
Ollier disease is caused by mutations in genes called IDH1 or IDH2. These mutations are somatic and mosaic, meaning they aren’t inherited from a parent but instead arise spontaneously during early embryonic development. Because the mutation only affects some cells in the body (those descended from the original mutated cell), the disease tends to show up in certain regions rather than uniformly across the skeleton. Research on tissue samples from 43 patients with Ollier disease found IDH1 or IDH2 mutations in 81% of them.
These mutations alter how cells process certain metabolic signals, leading to chemical changes that silence genes responsible for cartilage maturation. Normally, immature cartilage cells near a growth plate gradually transform into bone through a process called endochondral ossification. When the IDH mutations shut down the genes that drive this transformation, pockets of immature cartilage cells get left behind instead of converting to bone, forming enchondromas.
Because the mutations arise randomly rather than being passed down, Ollier disease does not run in families. Each case is essentially a one-time event during fetal development, and affected individuals do not have an increased chance of passing the condition to their children.
How It’s Diagnosed
Diagnosis typically begins with a plain X-ray, most often of the hand. The characteristic appearance is multiple expansile, bright (lucent) lesions sitting inside the bones, particularly in the short tubular bones of the fingers and metacarpals. These lesions often have a ground-glass appearance with a narrow transition zone between normal and abnormal bone. The bone around them may show thinning of the inner surface (endosteal scalloping) without a significant reaction from the outer bone layer.
MRI provides more detail when needed, revealing lobulated masses within the bone that light up brightly on fluid-sensitive sequences. MRI is especially useful for evaluating enchondromas in larger bones like the femur or tibia, where distinguishing a benign growth from an early cancer matters most. The combination of multiple enchondromas with an asymmetric, predominantly one-sided distribution on imaging is what separates Ollier disease from having a single isolated enchondroma, which is quite common and usually harmless.
Risk of Cancer
The most serious concern with Ollier disease is that enchondromas can transform into a malignant bone cancer called chondrosarcoma. Estimates of this risk vary widely in the medical literature, from 5% to 50%, largely because the risk depends heavily on which bones are involved.
Where the enchondromas sit matters enormously. People whose growths are limited to the small bones of the hands and feet have a relatively low chance of malignant transformation, around 14%. In contrast, when enchondromas involve the long bones of the legs and arms or the axial skeleton (pelvis, spine, ribs), the lifetime risk of developing chondrosarcoma climbs to 44% to 50%. Overall, patients with Ollier disease face roughly a 25% chance of malignant transformation by their 40s, with a lifetime risk approaching 40%.
Warning signs that an enchondroma may be turning cancerous include new or worsening pain at a previously painless site, rapid growth of a known lesion, and changes on imaging such as destruction of the bone’s outer layer or a growing soft-tissue mass. These changes, particularly in the pelvis, femur, or other large bones, typically prompt biopsy and further evaluation.
Treatment and Management
There is no cure for Ollier disease and no medication that stops enchondromas from forming. Treatment focuses on managing the orthopedic complications as they arise. Many people with mild disease, particularly those with involvement limited to the hands, need little or no intervention beyond monitoring.
For limb length differences greater than about 2 centimeters, several options exist. Mild discrepancies can be managed with a shoe lift. In children with enough growth remaining, a procedure called epiphysiodesis can slow growth on the longer side to let the shorter side catch up. For larger discrepancies, surgical limb lengthening is the primary approach. Historically this involved bulky external frames (Ilizarov-style fixators), but implantable lengthening nails placed inside the bone are now preferred when bone size allows. These internal devices are less cumbersome and allow correction of both length and alignment during the same procedure.
Angular deformities can be corrected acutely during surgery or managed in stages, with lengthening and straightening done at different times. In growing children, a technique called temporary hemiepiphysiodesis, where growth is slowed on one side of a growth plate, can gradually guide a crooked bone straighter over time. Fractures through enchondromas are treated with standard fracture care, though healing can be complicated by the abnormal bone.
Ollier Disease vs. Maffucci Syndrome
Maffucci syndrome is a closely related condition that also features multiple enchondromas, is driven by the same IDH1/IDH2 mutations, and carries a similar cancer risk from the cartilage tumors. The key difference is that Maffucci syndrome also involves benign vascular overgrowths, typically visible as soft, bluish lumps under the skin. These vascular lesions themselves become malignant in about 8.5% of Maffucci patients, a risk that is essentially absent in Ollier disease.
Another distinction is distribution. In Ollier disease, enchondromas are typically one-sided. In Maffucci syndrome, they tend to appear on both sides of the body. Because the vascular component of Maffucci syndrome sometimes develops later than the enchondromas, some patients are initially diagnosed with Ollier disease before the vascular growths appear and the diagnosis is revised.
Living With Ollier Disease
Because enchondromas generally stop forming once skeletal growth is complete, the orthopedic burden of Ollier disease tends to stabilize in early adulthood. The deformities and length differences that developed during childhood remain, but new ones rarely appear. The ongoing concern shifts primarily to cancer surveillance, particularly for people with enchondromas in the long bones or pelvis.
Periodic clinical and imaging follow-up is important throughout life. Any new pain at the site of a known enchondroma, especially pain that occurs at rest or at night, warrants prompt evaluation. MRI is the most sensitive tool for detecting early signs of malignant change. The frequency of surveillance imaging is typically tailored to the individual’s disease severity and the locations of their enchondromas, with higher-risk patients monitored more closely.