Enchondromatosis (Ollier's disease)

Enchondromatosis (Ollier's Disease)
Enchondromatosis, or Ollier's disease, is a disorder in which the ends of bones grow improperly and multiple cysts form all over the body. These large cartilaginous cysts form a benign bone tumor that can be very painful; however, they are not life threatening.[1] Ollier's disease is most common in the hand, femur, humerus, and tibia. The cartilage affects the inner layer of the periosteum,which is where the osteoblasts are located. Ollier's disease symptoms are usually discovered around the age range of 1-4. The symptoms are usually not seen at birth because the bones are still growing and it takes some time for the bones cysts to grow large enough to be detected. Most cases are sporadic, there have been a few cases where family tendency was indicated.[1]

History
Enchondromatosis or Ollier's disease was discovered by and named after the French surgeon Louis Ollier (1830-1900).[2] Ollier is primarily known for his work on bone and joint surgery.[2] He studied the regeneration of bones from the periosteum and developed new ways to treat wounds rather then amputation when the Germans invaded France.[2] Ollier made important contributions to surgery and he also devised a way for treating compound fractures. Since Ollier developed orthopedic surgery in France many patients from around the world came to be his patient.Ollier discovered enchondromatosis by examining multiple younger patients with large bone cysts in their hands and arms. Since Ollier was the first doctor to work with enchondromatosis the disease was also named after him.

Diagnosis and symptoms
Enchondromatosis diagnosis is based on clinical and conventional radiological findings. Physicians may use X-Rays’s, MRI’s, and Bone Biopsy's to determine the diagnosis of Ollier’s disease. Symptoms do not occur in enchondromatosis patients other than enlargement and pain of the infected area.

X-Ray



X-Ray's have shown enchondromas lesions at the diaphyseal or metaphyseal regions and sometimes lesions at the metaphyseal and epiphyseal regions. Most cases have shown the lesions do not cross the growth plate during growth periods. However, sometimes enchondromas have been found on X-Ray's crossing the growth plate before the plate has closed leading to limb length deformities. Affected diaphysis are short and massively enlarged, and these may show bending close to the metaphysis. Ulnar shortening is usually more relevant than shortening of the radius and fingers often show irregular sizes.[9]

MRI



Magnetic Resonance Imaging (MRI) has been shown to find large splenic haemangiomas in patients with enchondromatosis.[5] MRI diagnosis on patients with Ollier's disease also can check for other malignancies. Enchondromas tend to have lobulated borders with a cluster of numerous tiny locules of high-signal-intensity foci on T2-weighted images that appear to coalesce with one another and reflect the high fluid content of hyaline cartilage.[1]

Bone Biopsy's



A bone biopsy is a procedure in which a small sample of bone is taken from the body and looked at under a microscope for cancer, infection, or other bone disorders. Microscopic examination of enchondromas usually show multiple oval-shaped or round cartilaginous nodules in osseous portions of bone.[9] The reason bone biopsy's are important in the diagnosis of enchondromatosis is because they confirm the diagnosis of MRI and X-Ray's.

Treatment
Enchondromatosis is the abnormal growth of bone and cartilage in the human body. Beacause enchondromatosis is so rare, it is a very tough disease to treat. Enchondromatosis is most often found as a benign tumor known as enchondromas. Enchondromas are not dangerous to the body. However, the presence of pain most often means the benign tumor has turned malignant. The malignant tumor of enchondromatosis is known as enchodrosarcoma. Enchondrosarcomas are very complicated to treat. To this date, no medication can be prescribed to fight the disease. In the special case of bone fractures or growth defects surgery can be performed. Also,in the rare case that enchonromatosis turns malignant, surgery can be performed to remove the tumor. Surgery is used to keep the tumor from spreading to other parts of the body as well as to make growth defects less severe. Surgery is the last option to treat enchondromatosis because it is very painful. Other than malignant tumors not much can be done to treat enchondromatosis. To this date, there are no known cures for enchondromatosis[6].

Current Research
There is ongoing research concerning Enchondromatosis. One recent area of research is the formation of other diseases from Ollier's disease. In a recent case study published in 2008, researchers studied a young girl with syndromic malformation complex [3]. Syndromic malformation complex is a disease that results in extreme pressure on both the spinal cord and nerve roots. The young girl also presented an extented case of Enchondromatosis. These researchers concluded that the cartilaginous cysts formed in the bone of the vertebrae from her Enchondromatosis led to the formation of the syndromic malformation complex [3]. In this same study, they supported the hypothesis that Achondroplasia (a common form of dwarfism) patients seem to have a greater chance of producing Enchondromatosis [3]. This is because Achondroplasia affects various tissues of the body, including the cartilaginous growth plate in the skeleton, and Enchondromas are found to develop more closely to growth plate cartilage [3].

Other research on Enchondromatosis being greatly studied deals with the formation of the disease. Although it is readily known what Enchondromatosis is, why it happens is still being questioned. According to the Journal of Rare Diseases, it is still unknown whether Ollier's disease occurs because of a single mutation in a gene or a combination of mutations [4]. There is no evidence that Ollier's disease is passed on from parent to child, so the mutations seem to not be inherited [4]. Through scientific study, these researchers predict that Ollier's disease results from a mutation in the post-zygotic somatic region to result in mosaism [4]. In this same article, researchers discuss the risk of enchondromas to form into chondrosarcomas, or cancerous tumors [4]. This is another area of great research. They support evidence that the formation of cancerous tumors from Enchondromatosis come from varying expression of PTHrP to PTHR1 (both parathyroid hormone-related proteins) [4].

The expression of PTHrP and PTHR1 is an area of great research currently with Ollier's disease. Hopyan et al performed a series of studies on mutant PTHrP on transgenic mice and published their results in a recent article in Nature Genetics [7]. They found that the mutant, PTHR1, led to Enchondromatosis in vitro in transgenic mice [7]. The picture below, taken from this study, shows some significant results. The first column, pictures a, c, and e, are hyaline cartilage from transgenic control mice (not given PTHR1). The second column, pictures b, e, and f, are pictures from hyaline cartilage, but were of mice with added PTHR1. The second column shows areas where Enchondromas formed, especially in pictures b and f.