Osteochondroma is the Most Common Benign Bone Tumor

Osteochondroma is the most common benign bone tumor (see images below). The tumor is often diagnosed as an incidental finding. Osteochondromas account for approximately 35% of benign bone tumors and 9% of all bone tumors. Most are asymptomatic, but they can cause mechanical symptoms depending on their location and size.

Solitary osteochondroma. Anteroposterior radiograph of a pedunculated

osteochondroma of the distal femur. Solitary osteochondroma. CT scan of the pelvis depicting a massive solitary osteochondroma.

Solitary osteochondroma. Gross osteochondroma specimen at the time of resection. Bone stalk and overlying membrane on cartilage cap. As benign lesions, osteochondromas have no propensity for metastasis. In fewer than 1% of solitary osteochondromas, malignant degeneration of the cartilage cap into secondary chondrosarcoma has been described and is usually heralded by new onset of growth of the lesion, new onset of pain, or rapid growth of the lesion.[1, 2, 3]

Recent studiesPurandare et al studied the role of whole-body FDG PET-CT in evaluating sarcomatous transformation of osteochondromas in 12 patients with a diagnosis of osteocartilaginous lesions. Seven patients with histopathologic evidence of sarcomatous transformation to grade II

chondrosarcoma had moderate to high FDG uptake; 1 patient with a dedifferentiated chondrosarcoma had a focus of very intense uptake; and 4 patients with histopathologic or clinical diagnosis of a benign osteocartilaginous lesion had low FDG uptake. FDG uptake was also noted in an asymptomatic osteochondroma, which on histopathology revealed a grade II chondrosarcoma.[4] Florez et al performed a retrospective study of 113 solitary osteochondromas treated from 1970 through 2002. The authors found that the most frequent location was the distal femur. Six patients had a recurrence after treatment, and in 2 patients, the lesions became malignant and developed into chondrosarcoma. They noted that relapse of the exostosis is rare, occurring in approximately 2% of resections, and that growth of an osteochondroma or the presence of pain in older patients suggests a possible malignancy.[5] Heinritz et al reported on the clinical findings and results of molecular analyses of the EXT1 and EXT2 genesmutations of which lead to multiple osteochondromain 23 patients. In 17 of the 23 patients, novel pathogenic mutations were identified (11 in the EXT1 gene; 6 in the EXT2 gene). According to the authors, findings of this study extend the mutational spectrum and understanding of the pathogenic effects of EXT1 and EXT2 mutations.[6]Historically and currently, most osteochondromas are incidental findings and are treated solely with observation. If they remain asymptomatic, they can be ignored. Lesions that create mechanical symptoms, become painful, begin to enlarge, or cause growth disturbance have historically been treated with surgical removal, and this remains the mainstay of treatment.

Osteochondroma is a benign, cartilaginous neoplasm that is found in any bone that undergoes enchondral bone formation in its development. The World Health Organization (WHO) defines osteochondroma as a cartilage-capped bony projection on the external surface of a bone. It is found most commonly around the knee and the proximal humerus; however, it can occur in any bone. The osteochondroma may have a stalk, as in the first two images below, and be defined as pedunculated, or it may have a broad base of attachment and be considered sessile in nature, as in the last image below. Whether sessile or pedunculated, the medullary canal of the stalk and the bone are in continuity by definition.[7]

Solitary osteochondroma. Anteroposterior radiograph of a pedunculated

osteochondroma of the distal femur. Solitary osteochondroma. Lateral radiograph of a pedunculated osteochondroma of the distal femur. Orientation is away from the

growth plate, and medullary continuity is clear. Solitary osteochondroma. Lateral radiograph of a sessile osteochondroma of the distal femur. Osteochondroma is a hamartoma, and patients most commonly present in the second decade of life. Osteochondromas grow until skeletal maturity; growth generally stops once the growth plates fuse.[8] Slow growth from the cap may continue over time, as described by Virchow, but this usually stops by age 30 years. The actual frequency of osteochondromas is unknown because many are not diagnosed. Most are found in patients younger than 20 years, as in the image below. The male-to-female ratio is 3:1.

Solitary osteochondroma. Anatomic and age distribution of solitary osteochondromas. Osteochondromas can occur in any bone that undergoes enchondral bone formation, but they are most common around the knee. Although the exact etiology of these growths is not known, a peripheral portion of the physis is thought to herniate from the growth plate.[9] This herniation may be idiopathic or may be the result of trauma or a perichondrial ring deficiency. Whatever the cause, the result is an abnormal extension of metaplastic cartilage that responds to the factors that stimulate the growth plate and thus results in exostosis growth. This island of cartilage organizes into a structure similar to the epiphysis (see Workup, Histologic Findings, below). As this metaplastic cartilage is stimulated, enchondral bone formation occurs, developing a bony stalk. The histology of the cartilage cap reflects the classic, defined zones observed in the growth platenamely, a zone of proliferation, columniation, hypertrophy, calcification, and ossification. This theory is thought to explain the classic finding of the osteochondroma associated with a growth plate and growing away from the physis while maintaining its medullary continuity. The theory is also thought to explain the clinical behavior of the exostosis growing only until skeletal maturity. Genetic karyotyping has suggested that reproducible genetic abnormalities are associated with these benign growths and that they may actually represent a true neoplastic process, not a reactive one.[10, 11] This research is in the early stages, and further investigation is necessary.[12, 13,14, 15]

Osteochondromas are located adjacent to growth plates and develop away from the growth plate with time because they are essentially isolated growth plates. They are affected by, and respond to, various growth factors and hormones in the same manner as epiphyseal growth plates; thus, growth of an osteochondroma should cease at skeletal maturity. Osteochondromas are the most common benign bone tumors. They represent 35% of all benign tumors and 9% of all bone tumors. Most are diagnosed in patients younger than 20 years. A marked predilection for males exists; the male-to-female ratio is 3:1.[16] Although they can be located almost anywhere in the skeleton, almost half of osteochondromas are found around the knee, in either the distal femur or the proximal tibia.[17] See image below for age and anatomic distribution.

Solitary osteochondroma. Anatomic and age distribution of solitary osteochondromas. Osteochondromas are most commonly diagnosed incidentally on radiographs obtained for other reasons. The second most common presentation is a mass, which may or may not be associated with pain. Most of these lesions do not need to be treated, and asymptomatic lesions can be safely ignored. When painful, however, they need to be evaluated properly. Pain is usually caused by a direct, mechanical, mass effect of the osteochondroma on the overlying soft tissue. This can result in an associated sac or bursitis over the exostosis. Irritation of surrounding tendons, muscles, or nerves can result in pain.[18, 19] Pain can also result from fracture of the stalk of the osteochondroma from direct trauma. The bony cap of the stalk may infarct or undergo ischemic necrosis. Asymptomatic lesions require no treatment and can be monitored initially with radiographs and subsequently by clinical examination. Further investigation is indicated if the patient presents with a painful lesion or develops pain or an increase in size of a preexisting lesion. Such changes may represent either a new mechanical symptom or malignant degeneration. MRI is very useful for investigating these changes. The most common causes of pain are bursa formation, impingement, fracture of the stalk, and malignant degeneration.[20, 21, 22] Excision is the treatment of choice for symptomatic lesions. As with all lesions of muscle and bone, the physician must be confident of the diagnosis and well versed in the care of tumors, should the lesion in fact be malignant. If the surgeon has any doubt about the diagnosis of the lesion or the management of a potential malignancy, patient referral is the most appropriate course of action. In excising the lesion, it is important to avoid leaving any remnants of cartilage from the cap or any perichondrium, because this can allow recurrence. The reported rate of local recurrence is less than 2-5%.[23] The risk of recurrence is thought by some to be higher in the skeletally immature; therefore, resection might best be delayed until skeletal maturity is reached. Great care must be exercised with lesions close to the physeal plate in the immature patient, because of the risk of growth plate arrest and subsequent deformity. Osteochondromas can occur in many different locations in the body. Thus, a complete understanding of local anatomy is paramount to ensure that local structures are not harmed during surgical resection. Because these lesions arise from the metaphysis, particular care must be taken to avoid damage to the growth plate in the skeletally immature patient.

Plain radiography is the mainstay of imaging for osteochondroma. Good quality radiographs should be obtained in 2 perpendicular planes to characterize the lesion fully. Classic radiographic features include orientation of the lesion away from the physis and medullary continuity.[24] See images below.

Solitary osteochondroma. Anteroposterior radiograph of a pedunculated

osteochondroma of the distal femur. Solitary osteochondroma. Lateral radiograph of a pedunculated osteochondroma of the distal femur. Orientation is away from the

growth plate, and medullary continuity is clear. Solitary osteochondroma. Anteroposterior radiograph of sessile osteochondroma of the humerus. In certain bones, such as the pelvis and the scapula, CT scanning is a useful adjunct to localize the lesion. CT localization can be useful when planning resection.[25] See images below.

Solitary osteochondroma. CT scan of the pelvis depicting a

massive solitary osteochondroma. Solitary osteochondroma. CT scan of the same sessile osteochondroma of the humerus as in Image 6. MRI is needed only in cases in which malignancy is a concern or in which relevant soft-tissue anatomy needs to be delineated. MRI is the modality of choice to assess cartilage cap thickness, as in the image below. While not an absolute indication, cartilage cap thickness is related to malignancy. Thick cartilage caps (>4 cm) are suggestive of malignant degeneration, especially when they are associated with pain.

Solitary osteochondroma. MRI of sessile osteochondroma of the femur demonstrating the thickness of the cartilage cap. Bone scans, as a rule, are not useful in the workup of osteochondromas or for preoperative planning for resection.[26] Grossly, the stalk is contiguous with the intramedullary marrow. By definition, the medullary canal of the affected bone and the canal of the tumor are connected. The stalk is made up of mature bone. The cartilage cap, which tops the lesion and can be quite thick in children, is replaced by enchondral bone formation in maturing patients, as in the images below.

Solitary osteochondroma. Gross osteochondroma specimen at the

time of resection. Bone stalk and overlying membrane on cartilage cap. Solitary osteochondroma. Cut surface of surgical osteochondroma specimen. Cartilage cap and underlying bone with medullary continuity. On microscopic examination, the cartilage cap can exhibit varying amounts of cellularity. The cap has an overlying fibrous layer that contains mesenchymal cells, which are thought to be responsible for the lesion's growth.[27] The cells in the cartilage are orientated vertically, as is found in a growth plate. In skeletally immature patients, the cells undergo enchondral bone formation, as in the images below. While no specific cartilage cap thickness is an absolute indicator of risk for malignancy, less than 4 cm generally is thought to be in the range of normal. Further, the cap should not thicken in persons older than 30 years.

Solitary osteochondroma. Histology of cut osteochondroma

specimen. Cartilage cap and orientation of enchondral bone formation. Solitary osteochondroma. High-power view of benign cartilage cells arranged in vertical growth plate pattern. Osteochondromas are benign lesions and can be staged under the Musculoskeletal Tumor Society (MSTS) staging for benign lesions, as follows:y y y

Stage I - Inactive or static lesions Stage II - Actively growing lesions Stage III - Actively growing lesions that are locally destructive/aggressive

Most osteochondromas are stage I or II. However, significant deformity secondary to mass effect can occur in areas such as the radioulnar joint and tibiofibular joint. While classification is not perfect, such lesions could be considered stage III lesions, as in the image below. These cases likely represent a pressure erosive process, rather than a truly invasive process (as the staging for benign lesions is defined), a subtle but distinct biologic process.

Solitary osteochondroma. Radiograph demonstrating the deformation of the distal tibiofibular joint in a patient with a solitary osteochondroma.

In the rare case of malignant degeneration of the cartilage cap, the lesion is usually a low-grade chondrosarcoma that would be graded a low-grade extracompartmental lesion, MSTS stage IB. The treatment for symptomatic osteochondromas is resection. Care must be taken to ensure that none of the cartilage cap or perichondrium is left in the resection bed; otherwise, there may be a recurrence. Ideally, the line of resection should be through the base of the stalk; thus, the entire lesion is removed en bloc with its fibrous covering. Atypical or very large lesions should be investigated fully to exclude the remote possibility of malignancy. MRI is useful in assessing cartilage cap thickness. In the skeletally immature patient, care must be taken to avoid damage to the growth plate during the exposure and resection of the lesion. One small study evaluated surgical outcomes of pediatric patients with osteochondroma of the digits; average age at surgery was 3.6 years. The study recommends early surgical treatment for patients with nonepiphyseal metaphysis of the bone to improve motion and to prevent further finger deformity. However, tumor excision, which may include part of the articular surface, is recommended when tumors are laterally oriented and include less than one third of the joint surface.[28] Local anatomic constraints must be considered carefully so that the approach and resection do not damage nearby structures. CT scanning and MRI can be useful for lesions that arise from flat bones or that are located in difficult areas, such as lesions around the hip or scapula.[29] Once the osteochondroma is exposed, dissection is limited to the base of the lesion so that an osteotome can be used to shear off the base at the level of the host bone cortex. Care is required to ensure that the resection neither violates normal host cortex by straying too deep nor leaves residual lesion by staying too shallow. The overlying bursa should be left intact, and the loose adhesive tissue should be dissected away so that the lesion and the bursa are removed en bloc. The resected surface of the host bone can be rasped smooth, and if needed, bone wax can be packed on the cut surface to stop bleeding. Once the specimen is removed and pathologic confirmation is received, the wound should be irrigated well and a surgical drain can be placed if needed. The drain should exit in line with the wound. Most osteochondromas allow the patient to return to activity as tolerated. However, after resection of a large sessile lesion, restriction of activities should be considered because the stress riser created by the violation of the cortex may increase the risk of fracture.The local recurrence rate after resection of osteochondroma is about 1.8%.[30] Once the wound is healed, follow-up on an as-needed basis is reasonable if no associated bone deformity or potential growtharrest concerns exist. Complications after surgical resection of osteochondromas are rare. Considerations include physeal disturbance or growth arrest, fracture, recurrence, incorrect diagnosis, and hematoma formation.

For solitary osteochondromas, the outcome and prognosis after surgery are excellent, with excellent local control and a local recurrence rate of less than 2%.[31, 5] The process is a benign one; thus, the prognosis is usually one of complete recovery. Poorer outcomes usually are related to the morbidity associated with the exposure required to remove the lesion or associated with secondary bone deformity, but the latter is usually observed in the multiple hereditary form of the disease. Genetic karyotyping suggests that reproducible genetic abnormalities are associated with these benign growths and that they may represent a true neoplastic process, not a reactive one.[10, 11] Research is in the early stages, and further investigation is needed.[12, 13, 14, 15] Biologic therapies for osteochondromas may be possible in the future. Sources : Emedicine and Medscape

Osteochondroma is a benign tumor that occurs in areas of bone and cartilage. Tumors are most often found in the long bones, especially near the knee or shoulder. Lesion can either be sessile or pedunculated. Occurs in people aged under 20, with a male to female ratio of 1.5: 1 Clinically presents with pain due to mechanical irritation or as a painless mass. Sessile tumors appears as wide ranging with trumpet-shaped deformity. Pedunculated lesions appear distally. Introduction and Definition: Osteochondroma, or osteocartilaginous exostosis, is the most common skeletal neoplasm. The cartilage capped subperiosteal bone projection accounts for 20-50% of benign bone tumors and 10-15% of all bone tumors.Osteochondromas are most likely caused by either a congenital defect or trauma of the perichondrium which results in the herniation of a fragment of the epiphyseal growth plate through the periosteal bone cuff. Osteochondromas can either be flattened (sessile) or stalk-like (exostosis) and appear in a juxta-epiphyseal location. Osteochondromas are also the result of radiation therapy in children. After the close of the growth plate in late adolescence there is normally no further growth of the osteochondroma. Incidence and Demographics: The lesions occur only in bones that develop from cartilage (endochondral ossification). Osteochondromas are found most often in long bones, especially the distal femur and proximal tibia, with 40% of the tumors occurring around the knee. Osteochondromas occur most frequently in the first two decades of life with a ratio of male to female of 1.5 to 1. Symptoms and Presentation: Clinically, osteochondromas present with pain due to mechanical irritation or a painless mass. A fracture can occur through the stalk of the lesion which also causes pain.

X-Ray Appearance and Advanced Imaging Findings: Plain films are normally enough to diagnose osteochondromas. Sessile lesions cover a wide area and as a result cause metaphyseal widening or a "trumpet shaped deformity" on x-ray. Lesions with stalks are often found more distally and are common over the posterior femoral metaphysis. CT is helpful in determining if the marrow and cortices of the lesion are continuous with the bone. The relationship of the lesion to other structures and the thickness of the cartilage cap are best delineated with MRI. Histopathology findings: On gross examination, an osteochondroma is an irregular bony mass with a bluish gray cap of cartilage. Opaque yellow cartilage has calcification within the matrix. The base of the lesion has a rim of cortical bone and central cancellous bone. Occasionally, a bursae develops over an osteochondroma. Normally, the cartilage cap ranges from 1-6 mm thick. Over 2 cm of cartilage or renewed growth of a dormant lesion are signs of possible malignant transformation.Under the microscope, an osteochondroma has endochondral ossification on the basal surface of hyaline cartilage so it resembles a normal growth plate with rows of chondrocytes. The cartilage is more disorganized than normal, has binucleate chondrocytes in lacunae, and is covered with a thin layer of periosteum. Treatment Options for this Tumor: There is no treatment necessary for asymptomatic osteochondromas. If the lesion is causing pain or neurologic symptoms due to compression it should be excised at the base. Outcomes of Treatment and Prognosis: As long as the entire cartilage cap is removed there should be no recurrence. Patients with many especially large osteochondromas should have regular screening exams and radiographs to detect malignant transformation early. Special and Unusual Features: Hereditary multiple osteochondromatosis is an autosomal dominant condition that can lead to both sessile and pedunculated lesions. The lesions may occur on different bones or on the same bone, and symptoms present in the first decade of life. The risk of malignant transformation to chondrosarcoma in hereditary multiple osteochondromatosis is unknown, but may be 25-30% compared to approximately 1% for a solitary osteochondromas.3 The risk of malignant degeneration increases as the number and size of the osteochondromas increases. In general, a sessile lesion is more likely to degenerate into sarcoma than an exostosis. Suggested Reading and Reference: References Giudici, M.A. et al, Cartilaginous Bone Tumors, Radiologic Clinics of North America,31(2):237-259, March 1993. Bullough, Peter, Orthopaedic Pathology (third edition), Times Mirror International Publishers T Limited, London,1997 Gitelis, S. et al, Benign Bone Tumors, Instructional Course Lectures, 45:42646, 1991. Huvos, Andrew, Bone Tumors: Diagnosis. Treatment and Prognosis, W.B. Saunders, Co., 1991.

Osteochondroma is a benign tumor, originating from the components of bone (osteocytes) and components of cartilage (chondrocytes). These tumors often invade the long bones in the metaphysical, especially in the area around the knee. These tumors are mainly found in adolescents whose growth is active and in young adults. Symptoms of pain occurs when there is an emphasis on exchanges or the surrounding soft tissue. Hard lumps that can be found in the area around the lesion.

Locations are usually in the metaphysical osteochondroma of long bones especially around the knee joint (articulatio genu), particularly the distal femur, proximal tibia and proximal humerus. It can also be found on the scapula and ilium bones. Bone is the third organ most frequently invaded by metastatic disease (disease of an organ that spreads to other body parts). Cancer most often spreads to the bone are breast, lung, prostate, thyroid and kidney. When compared between carcinomas and sarcomas, the more frequent type of cancer that spread to bone are carcinomas. The first bone is usually affected are the ribs, pelvis and spine; the bones of the distal (tip of the body) are rarely affected. The spread occurs when a single tumor or a set of tumor cells into the bloodstream and through the blood vessels in the canal Harves to the bone marrow, where they proliferate and form new blood vessels. Batson venous plexus in the spine allows the cancer cells into the circulation spine without having to go through the lungs first. Blood flow in this plexus is so slow that cancer cells can survive and increase the incidence of prostate cancer metastases to the spine. In plain genu looked away from the bony joints in the cortex and spongiosa is still normal. Protrusion of the bone is shaped like cauliflower (couliflower) with components osteocytes (bone hard) as a component of the stalk and chondrocytes (cartilage) as interest. Inhomogen protrusion of bone density (opaque on the flower stalk and lusen). Sometimes seem opaque calcifications in the form of spots due to a calcified kondral components. Tumors can be either single or multiple depending on the type. OSTEOCHONDROMA is a benign bone neoplasm that most often obtained. By some experts is not considered a neoplasm, but as a hamartoma (new growth, where the cells can be grown). There at the age of young adults with complaints of a hard lump and no pain, grow very slowly. Found in the metaphysical long bone, especially in the distal femur, proximal tibia and proximal humerus (35%), pelvis and scapula. X-rays are two forms: stemmed / pedunculated and have a wide base (sessile). Preview image shows bone stemmed plain outside the growth area of ??the metaphysical. Form a uniform lesions, cartilage with calcification. Corteks and medulla are connected by the lesion. When the tumor gave a complaint for suppressing nearby structures such as tendons, nerves, then performed excision. The prognosis is good. Complications of malignant degeneration of approximately 1%. Immediately contact your doctor to find out the disease more. Osteochondroma (Bone Tumor) Solitary Osteochondroma Symptoms Diagnosis Treatment Research on the Horizon Multiple Osteochondromatosis

Symptoms Diagnosis Treatment Osteochondromas occur as solitary osteochondroma (osteocartilaginous exostosis) or as multiple osteochondromatosis. These are discussed separately. Solitary Osteochondroma Solitary osteochondroma is a developmental abnormality of bone. It occurs when part of the growth plate forms an outgrowth on the surface of the bone. This bone outgrowth may or may not have a stalk. When a stalk is present, the structure is called pedunculated. When no stalk is present, it is called sessile. An osteochondroma may grow in a child or adolescent. Its growth usually stops at maturity. Solitary osteochondromas are thought to be the most common noncancerous (benign) bone tumor. They account for 35 percent to 40 percent of all benign bone tumors. Solitary osteochondroma is diagnosed in patients aged 10 to 30. It occurs equally in males and females. It does not result from injury. It is thought to arise during skeletal growth when bone grows away from the growth plate instead of in line with it. Because the cause of solitary osteochondroma is unknown, doctors have not been able to find a way to prevent it. Top of page Symptoms The most common symptom of an osteochondroma is a painless bump near the joints. The knee and shoulder are more commonly involved. Solitary osteochondroma can be found at the ends of any long bone and along the pelvis and bones that make up the shoulder. If the stalk of a pedunculated osteochondroma breaks, pain and swelling may start immediately. An osteochondroma can be located under a tendon. When it is, snapping of the tissue over the tumor may cause activity-related pain. An osteochondroma can be located near a nerve or blood vessel, such as behind the knee. When it is, there may be numbness and tingling in that extremity. A tumor that presses on a blood vessel may cause periodic changes in blood flow. This can cause loss of pulse or changes in color of the limb. Changes in blood flow resulting from an osteochondroma are rare. Top of page Diagnosis A plain X-ray will show the bony growth. A magnetic resonance imaging (MRI) scan may be used to look for cartilage on the surface of the bony growth. Such cartilage in an adult patient

should be checked for cancer if it is larger than two centimeters in size, or if there is pain. A computed tomography (CT) scan may also be used. Top of page Treatment Nonsurgical Treatment Most of the time, solitary osteochondroma is not removed surgically. The doctor will carefully observe it. He or she may want to take regular X-rays to keep track of any changes. Surgical Treatment When surgery is recommended, it is best to wait until growth is complete (a mature skeleton by X-ray evaluation) before removing a solitary osteochondroma. This decreases the chance of the tumor growing back. Surgery may be considered if the osteochondroma:y y y

Is causing pain with activity Puts pressure on a nerve or blood vessel Has a large cap of cartilage

The osteochondroma is removed at the level of the normal bone. Some of the inside of the bone may also be removed. Top of page Research on the Horizon Osteochondromas are thought to be associated with a gene called EXT 1. This is currently poorly understood. Researchers are investigating it. Top of page Multiple Osteochondromatosis Multiple osteochondromatosis is also called multiple osteocartilaginous exostosis, multiple hereditary exostosis (MHE), familial osteochondromatosis, multiple hereditary osteochondromatosis, or diaphyseal aclasia.

Plain radiographs of the proximal fibula of a 15-year-old girl presenting with a painless, firm lateral leg mass. Left: Anteroposterior view shows a well-marginated osseous lesion superimposed on the proximal fibula, but the lateral view (center) shows continuity of the medullary cavity of the long bone with the center of the lesion. Right, Computed tomography shows the medullary space in continuity with the lesion, and a small cartilage cap, both of which are characteristic of an exostosis. Arrows indicate the osteochondroma.(Reproduced with permission from Richards BS (ed): Orthopaedic Knowledge Update: Pediatrics. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1996.)

About 70 percent of the time, it is inherited. About 30 percent of the time, it occurs randomly. Multiple osteochondromatosis affects males more often than females. It usually happens within the first three decades of life. Alterations in genes called EXT genes are thought to be the cause of this disease. It can be passed along in families. There is no other known risk factor or cause. There is increased risk of benign tumors changing to cancer (malignant transformation). Top of page Symptoms Symptoms are the same as solitary osteochondroma. The number and location of osteochondromas varies. A patient may also have deformities of the forearms, a short stature, and knock-knees and ankles. This is caused by abnormal growth in the bones affected by the osteochondromas. Symptoms and signs of a tumor becoming cancerous are:y y y

Growth of an osteochondroma after puberty Pain at the site of an osteochondroma A cartilage cap larger than two centimeters

Top of page Diagnosis

Preoperative (left) and postoperative (right) radiographs of the forearm of a 21-year-old woman with multiple osteochondromas and restricted pronation and supination of the forearm. Postoperatively, she regained nearly complete pronation and supination. Arrows indicate the osteochondromas.(Reproduced with permission from Aboulafia AJ, Temple TH, Scully SP: Treatment of benign bone tumors, in Beaty JH (ed): Instructional Course Lectures Volume 51. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002.)

It is diagnosed when two or more osteochondromas are seen on plain X-rays. Multiple osteochondromatosis has been associated with EXT 1 and EXT 2 genes. These genes are now being studied. The way they act is not well understood. X-ray findings are the same as with solitary osteochondromas. If cancer is suspected, you may need a thorough evaluation. This includes magnetic resonance imaging and computed tomography scans of the tumor. Pain at the site of a mass or growth after puberty should be evaluated by a doctor who specializes in treatment of bone tumors. The most common malignancy found in this transformation is called chondrosarcoma. A computed tomography scan of the chest helps look for any disease that may have traveled through the bloodstream to the lungs.

Preoperative (left) and postoperative (right) CT scans of a 25 year old man with sciatica. Osteochondroma arising from the sacrum was incidentally discovered during CT scan of the spine performed for evaluation of sciatica. In the postoperative cut scan, metallic clips identify the site of the resection. The osteochondroma was seen to displace the sacral plexus. Postoperatively, the patient's sciatica resolved completely. Arrow indicates the osteochondroma.(Reproduced with permission from Aboulafia AJ, Temple TH, Scully SP: Treatment of benign bone tumors, in Beaty JH (ed): Instructional Course Lectures Volume 51. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002.)

Sometimes the doctor may remove a piece of tissue from the tumor (biopsy). This is used to look at cells under a microscope. Top of page Treatment

Nonsurgical Treatment Most of the time, multiple osteochondromas are not removed surgically. Tumors that do not show signs of cancer are watched carefully. Deformities such as knock-knees or ankles may need surgery to straighten the bone. Surgical Treatment The tumor may be completely removed. This may also include taking out a whole portion of bone, which may need to be replaced with a prosthesis. Chemotherapy and radiation therapy are not usually needed. Top of page Last reviewed: October 2007 AAOS does not endorse any treatments, procedures, products, or physicians referenced herein. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific orthopaedic advice or assistance should consult his or her orthopaedic surgeon, or locate one in your area through the AAOS "Find an Orthopaedist" program on this website.

OsteochondromaWhat is osteochondroma?Also called osteocartilaginous exostoses, osteochondroma is an overgrowth of cartilage and bone near the end of the bone near the growth plate. This type of overgrowth can occur in any bone where cartilage eventually forms bone. Most commonly, it affects the long bones in the leg, the pelvis, or scapula (shoulder blade). Osteochondroma is the most common benign (non-cancerous) bone growth. The lesion usually occurs during skeletal growth - between the ages of 10 and 30 years. It affects males and females equally.

What causes osteochondroma?While the exact cause of osteochondroma is not known, there is a genetic link, indicating that there is a form of the disorder that is inherited. There is also a non-inherited form of the disorder.

What are the symptoms of osteochondroma?The following are the most common symptoms of osteochondroma. However, each individual may experience symptoms differently. Symptoms may include:y y

a hard, immobile, detectable mass that is painless lower-than-normal-height for age

y y y

soreness of the adjacent muscles one leg or arm may be longer than the other pressure or irritation with exercise

Often individuals with osteochondroma will have no symptoms at all. The symptoms of osteochondroma may resemble other medical conditions or problems. Always consult your physician for a diagnosis.

How is osteochondroma diagnosed?In addition to a complete medical history and physical examination, diagnostic procedures for osteochondroma may include the following:y y

y

x-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film. computed tomography scan (Also called CT or CAT scan.) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce crosssectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays. magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.

Treatment for osteochondroma:Specific treatment for osteochondroma will be determined by your physician based on:y y y y y

your age, overall health, and medical history extent of the disease your tolerance for specific medications, procedures, and therapies expectation for the course of the disease your opinion or preference

Treatment for osteochondromas varies significantly depending on the size of the overgrowth and the symptoms of the individual. Treatment may include:y y

surgery (to remove the mass) medications (to control pain)

If there is no sign of bone weakening or increased overgrowth, observation only may be suggested. Careful follow-up with a physician to monitor bone growth may be recommOHIO state medical centre