About enchondromatosis

What is enchondromatosis?

Ollier disease is a rare skeletal disorder characterized by abnormal bone development (skeletal dysplasia). While this disorder may be present at birth (congenital); it may not become apparent until early childhood when symptoms, such as deformities or improper limb growth, are more obvious. Ollier disease primarily affects the long bones and cartilage of the joints of the arms and legs, specifically the area where the shaft and head of a long bone meet (metaphyses). The pelvis is often involved; and even more rarely, the ribs, breast bone (sternum), and/or skull may also be affected.

Ollier disease manifests as greater than normal growth of the cartilage in the long bones of the legs and arms so that growth is abnormal and the outer layer (cortical bone) of the bone becomes thin and more fragile. These masses of cartilage are benign (non-cancerous) tumors known as enchondromas. Enchondromas may occur at anytime. After puberty these growths stabilize as cartilage is replaced by bone. In rare cases, the enchondromas may undergo malignant changes (e.g., chondrosarcomas). The exact cause of Ollier disease is not known, although in some cases it may be inherited as an autosomal dominant genetic trait.

When the enchondromas of Ollier Disease are accompanied by substantial, most often benign, proliferation of blood vessels (hemangiomas), the array of symptoms is known as Maffucci Syndrome.



What are the symptoms for enchondromatosis?

Ollier disease is not always apparent at birth, but symptoms will usually become evident by early childhood. Between the ages of one and four years, abnormal and/or Slow growth of arms and legs is often observed. Usually one leg and/or arm is affected, but both legs and/or arms may be involved. If both legs are involved, Short stature may result; if only one leg is involved, then an affected individual may limp.

The pelvis is sometimes involved and rarely, the ribs, breast bone (sternum), and/or skull may be affected. Deformities may also develop in the wrists and ankles. Limb shortening and bowing of the long bones may occur in some affected individuals.

Ollier disease also hampers proper development of bone (ossification). Fractures are a common occurrence in people affected by this disorder and usually heal well. In some patients, the development of some forms of malignant bone growths has been associated with Ollier disease.

Other rare complications can arise, such as gliomas and juvenile granulosa cell tumors. Gliomas are a type of brain tumor; they are referred to as intra-axial brain tumors, which refer to the growth of the brain tumors within the brain tissue itself. Juvenile granulosa cell tumor (JGCT) is a rare ovarian cancer; it has a favorable prognosis if diagnosed early.



What are the causes for enchondromatosis?

The underlying cause of Ollier disease is not known. Changes (mutations) in IDH1, IDH2 and PTHR1 genes have been linked to Ollier disease and Maffucci syndrome. The mutations are due to somatic mosaicism, which means that the mutation is present only in a percentage of the cells, not all the cells in the body. In Ollier disease, the mutation is present only in the enchondromas.

So far, all the cases of Ollier disease have been sporadic in their families and not inherited. But, in theory, if a gene mutation is present in the egg or sperm (germline), the condition could be passed on in an autosomal dominant pattern. Dominant genetic disorders occur when only a single copy of a non-working gene is necessary to cause a particular disease. The non-working gene can be inherited from either parent or can be the result of a de novo mutated (changed) gene in the affected individual. The risk of passing the non-working gene from an affected parent to an offspring is 50% for each pregnancy. The risk is the same for males and females.



What are the treatments for enchondromatosis?

Surgical correction of deformities of the affected limb(s) has been helpful. In severe cases, artificial (prosthetic) joint replacement may become necessary. Fractures routinely heal without complications. A supportive team approach for children with Ollier disease may be of benefit. Such a team approach may include physical therapy and other medical, social, or vocational services. Other treatment is symptomatic and supportive.



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