1, General clinical features of multiple osteochondromas.
Multiple osteochondroma (HME) is an autosomal dominant disorder characterized by multiple exophytic bone celebrations involving cartilaginous bone, also known as multiple exophytic bone warts, epiphyseal sequelae or osteochondromatosis, etc. The size and number of osteochondromas grow with the growth of the skeleton and stop growing when the skeleton stops growing.
The disease is characterized by abnormal epiphyseal shaping, osteochondroma formation, and impaired epiphyseal development due to ectopic proliferation of chondrogenic cells, which involves the epiphysis. This tumor often occurs symmetrically, more in the lower extremities than in the upper extremities, most often in the epiphysis of long bones, most commonly in the lower femur and upper tibia, followed by the humerus and fibula, and also in flat bones such as the ilium, scapula, clavicle, and ribs, and occasionally in the transverse processes of the spine.
About 60% of patients with the disease may develop forearm deformity due to the involvement of the distal ulna, mainly manifesting ulnar shortening and a series of secondary deformities such as radial curvature, ulnar tilt of the distal radial epiphysis, ulnar displacement of the carpal bone, and dislocation of the lower ulnar radial joint.
About 2/3 of patients with multiple osteochondromas (HME) have a positive family history, with an incidence of ≥1/50,000, an ectopic rate of 66.7-100%, and a malignancy rate of 0.9-2.9%. The number of osteochondroma sites in a family with multiple osteochondrosarcoma varies, generally 15-18
The number of osteochondroma sites in a family varies and is generally 15-18.
2. Complications of multiple osteochondromas.
Prevention of complications or early detection of complications can help improve the treatment outcome and prognosis of patients with multiple osteochondromas.
(1) Skeletal deformity: About 60% of patients with this disease may develop forearm deformity due to the involvement of the distal ulna.
(2) Malignancy: multiple osteochondromas (HME) are mostly benign tumors, and about 0.9-2.9% malignantly change to osteochondroma.
(3) Pseudoaneurysm: Pseudoaneurysm is a more common complication of osteochondroma, and there is no significant correlation with patient age and gender.
(4) Dislocation of the radial tuberosity: chondrosarcoma tends to invade the long bones, resulting in dislocation of the joint due to changes in the inclination of the articular surface of the radial head and the longitudinal axis of the radius.
(5) Pathological fracture: It is less common and usually occurs easily in the distal tibia and humerus backbone.
3. Basic treatment principles of multiple osteochondromas.
The presence of multiple osteochondromas does not necessarily require resection. Like solitary osteochondroma, multiple osteochondroma stops growing after the epiphysis closes. Because of its multiplicity, surgical treatment is difficult to remove all of them, and surgery before epiphyseal closure may cause early epiphyseal closure and affect pediatric development.
The current indications for surgery are.
①The tumor is large and affects the aesthetics;
② Clinical symptoms and compression of adjacent blood vessels and nerves;
③The tumor may cause the adjacent joints to be impaired and 1/4 of the joints may be deformed, so the tumor should be removed to correct the deformity;
④Tumor with malignant change or those osteochondroma located in medial skeleton. MO malignant chondrosarcoma is more common than single tumor, and most of them are single tumor malignant to peripheral chondrosarcoma.
Generally speaking, for those with relatively mild deformity or delayed bone development, the age of surgery can be appropriately postponed; while children with early onset of deformity, rapid progress and heavy deformity especially serious destruction of epiphyseal plate should be operated early, before the skeleton is mature, and appropriately over-extended to prevent the recurrence of deformity by the method of overkill.
4. Genetic diagnosis and genetic counseling for multiple osteochondromas
Current studies suggest that multiple osteochondromas are associated with at least three genes: namely, the EXT1 gene localized on 8q24.11-q24.13 and the EXT2 gene localized on 11p11-13 and the EXT3 gene on 19p. Among them, EXTl and EXT2 have been cloned, and mutations in EXTl or EXT2 genes will lead to abnormal heparan sulfate synthesis, which in turn will lead to abnormal cartilage development.
The detection of mutations in EXTl and EXT2 genes can be applied to clinical genetic diagnosis and genetic counseling of HME patients, and most importantly, to lay the foundation for prenatal diagnosis to avoid the inheritance of the disease to the next generation. the fragments of the coding region of EXTl and EXT2 genes are long, and their mutations not only involve the coding region, but also a significant part of them are located in splice sites or even regulatory regions, so direct detection is time-consuming and laborious. The emergence of second-generation sequencing has improved the detection rate and detection efficiency to a certain extent.