Osteochondroma - Multiple Hereditary Exostosis

Author: Timothy J. Evans, MD


Osteochondroma is a non-cancerous growth of bone that often occurs near joints, most commonly the knee, hip and shoulder. These growths are thought to occur when part of the growth plate begins growing in the wrong direction. They will typically arise in late childhood or adolescence, grow during puberty and then remain stable once the person’s growth plates have closed.

The vast majority of these growths occur randomly. However, there are a small subset that are associated with a genetic alteration called multiple hereditary exostoses (MHE). As a result of the genetic alterations that lead to this diagnosis, the evaluation, management and surveillance of patients will be different and will be discussed separately throughout this outline.


Patients will often present with a hard, nonmobile mass near a joint. This mass may be present without symptoms; however, can be associated with tenderness upon palpation or pain with joint motion. Sometimes these lesions can cause the bones to grow incorrectly causing bone/joint deformities. Osteochondromas that have been the same size for many years and then suddenly increase in size should be evaluated promptly. Other symptoms that should provoke a patient to be evaluated include increasing pain at rest or with movement, or redness.


Your orthopedic surgeon will obtain a full history and evaluation. The physical examination will reveal many of the findings previously discussed – a hard, nonmobile, nontender/mildly tender mass within close proximity to a joint.


All patients who present with a mass in an extremity will undergo X-ray evaluation as the initial step. In addition to X-rays, your surgeon may find it necessary to order other additional tests including computer tomography (CT) scans, magnetic resonance imaging (MRI) or nuclear medicine scans (i.e. bone scan). All of these imaging studies provide different information and all of this information is then combined to assist with the diagnosis.


As discussed, patients who present with pain, mass or other symptoms within their extremities will undergo initial imaging evaluation with radiographs. The radiographs in patients with osteochondroma will reveal a mass that is connected to the bone and often appears “mushroom-like,” but could also appear more like a “mountain range.” Radiographs of each example are below (Figure 1).


 Figure 1



Osteochondromas are benign, which means they are not cancer and do not pose any risk of spreading. However, there is a chance osteochondromas could turn into a more aggressive entity – a process referred to as malignant transformation. In the “sporadic” form, this risk is very low, less than 1% of the time. However, in patients who are diagnosed with MHE there is a lifelong risk of ~10%. For this reason, in patients diagnosed with MHE, it is often recommended to receive lifelong surveillance in the form of yearly visits to their orthopedic surgeon for a physical examination and imaging. In general, osteochondromas should not limit a patient’s lifestyle and patients should be able to participate in any physical activities of their choosing. Orthopaedic oncologists specialize in the treatment of bone tumors, such as osteochondromas, as well as MHE.

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This is not intended as a substitute for professional medical advice and does not provide advice on treatments or conditions for individual patients. All health and treatment decisions must be made in consultation with your physician(s), utilizing your specific medical information. Inclusion in this is not a recommendation of any product, treatment, physician or hospital.