Hereditary multiple osteochondromas
Hereditary multiple osteochondromas is a condition in which people develop multiple benign (noncancerous) bone tumors called osteochondromas. The number of osteochondromas and the bones on which they are located vary greatly among affected individuals. The osteochondromas are not present at birth, but approximately 96 percent of affected people develop multiple osteochondromas by the time they are 12 years old. Osteochondromas typically form at the end of long bones and on flat bones such as the hip and shoulder blade.Multiple osteochondromas can disrupt bone growth and can cause growth disturbances of the arms, hands, and legs, leading to short stature. Often these problems with bone growth do not affect the right and left limb equally, resulting in uneven limb lengths (limb length discrepancy). Bowing of the forearm or ankle and abnormal development of the hip joints (hip dysplasia) caused by osteochondromas can lead to difficulty walking and general discomfort. Multiple osteochondromas may also result in pain, limited range of joint movement, and pressure on nerves, blood vessels, the spinal cord, and tissues surrounding the osteochondromas.Osteochondromas are typically benign; however, in some instances these tumors become malignant (cancerous). Researchers estimate that people with hereditary multiple osteochondromas have a 1 in 20 to 1 in 200 lifetime risk of developing cancerous osteochondromas (called sarcomas).
Defects in O-xylosylglycan synthesis
Multiple osteochondromas is an autosomal dominant, genetically heterogeneous disorder characterised by development of two or more cartilage capped bony outgrowths (osteochondromas) of the long bones.
Multiple osteochondromas (MO) is characterised by development of two or more cartilage capped bony outgrowths (osteochondromas) of the long bones. The prevalence is estimated at 1:50,000, and seems to be higher in males (male-to-female ratio 1.5:1). Osteochondromas develop and increase in size in the first decade of life, ceasing to grow when the growth plates close at puberty. They are pedunculated or sessile (broad base) and can vary widely in size. The number of osteochondromas may vary significantly within and between families, the mean number of locations is 15-18. The majority are asymptomatic and located in bones that develop from cartilage, especially the long bones of the extremities, predominantly around the knee. The facial bones are not affected. Osteochondromas may cause pain, functional problems and deformities (especially of the forearm), which may provide reason for surgical removal. The most important complication is malignant transformation of osteochondroma towards secondary peripheral chondrosarcoma, which is estimated to occur in 0.5-5% of cases. MO is an autosomal dominant disorder and is genetically heterogeneous. Germline mutations in the tumour suppressor genes, EXT1 or EXT2, are found in almost 90% of MO patients. The EXT genes encode glycosyltransferases, catalyzing heparan sulphate polymerization. The diagnosis is based on radiological and clinical documentation, supplemented with, if available, histological evaluation of the osteochondromas. MO should be distinguished from metachondromatosis, dysplasia epiphysealis hemimelica and Ollier disease (see these terms). Osteochondromas are benign lesions and do not affect life expectancy. If the exact mutation is known antenatal diagnosis is technically possible. Management includes removal of osteochondromas when they are the cause of complaints. Removed osteochondromas should be examined for malignant transformation towards secondary peripheral chondrosarcoma. Patients should be well instructed and regular follow-up for early detection of malignancy seems justified. For secondary peripheral chondrosarcoma, en-bloc resection of the lesion and its pseudocapsule with tumour-free margins should be performed, preferably in a bone tumour referral centre.
Also Known AsDiaphyseal aclasisMultiple cartilaginous exostosesMultiple osteochondromasBessel-Hagen diseaseGlucuronyltransferase/N-acetylglucosaminyltransferase deficiencyEXT1/EXT2-CDG
Related ICD 10 COde ICD 10 Code Q78.6