Patient's question:
I am a patient with multiple osteochondromas. I also deeply understand the psychological impact this disease can have on people. As someone who has gone through it, I don't want my daughter to suffer from this pain. How can this disease be prevented?Doctor's answer:
Multiple hereditary osteochondromas have three characteristics: ① they are hereditary ② bone shortening or deformity ③ a high incidence of malignant transformation into peripheral chondrosarcoma. The ratio compared to solitary osteochondromas is 1:10. Due to the hereditary feature, the onset of symptoms is earlier than in solitary osteochondromas, generally occurring before the age of 10. Mild cases (especially in females) can remain latent throughout life. It is more common in males, with a male-to-female ratio of 2:1.Two-thirds of cases show a hereditary pattern. If one parent has multiple hereditary osteochondromas, about half of their offspring will inherit the condition, with a higher prevalence in male offspring. In families with this condition, if a male member is normal, he will not pass it on to his descendants; conversely, in the same family, even a normal female can pass on the disease. In other words, in males, both the disease and the ability to inherit it are expressed simultaneously; in females, the disease can be latent or mild but can still be passed on to offspring.
It is generally diffuse and symmetrical, affecting all bones undergoing endochondral ossification, with the most common sites being the metaphyseal regions of growing bones, particularly near the knees, shoulders, hips, wrists, and ankles, but it is rare and mild when occurring in the elbows. Multiple hereditary osteochondromas are also common in the axial skeleton, occurring near the ossification centers of the second or epiphyseal bones. In the scapula, it primarily affects the vertebral margin, inferior angle, acromion, glenoid, and coracoid. In the pelvis, it primarily affects the iliac crest. In the spine, it mainly occurs on the spinous and transverse processes. In the ribs, it is more common at the costochondral junctions or posterior ends. Except for the calcaneus, which has a secondary ossification center, multiple hereditary osteochondromas do not occur in the carpal or tarsal bones, as their development is similar to that of the epiphyses.
Symmetrical multiple osteophytes can be seen and felt. In more severe cases, their presentation is characteristic, and diagnosis can be made based on physical examination alone. In more severe cases, limb shortening may occur, sometimes very significant and diffuse, resembling achondroplasia. However, multiple hereditary osteochondromas do not exhibit the features of achondroplasia, and cartilage growth function is normal. In fact, limb shortening is not caused by abnormal cartilage growth but rather by the consumption of cartilage proliferative potential by extramedullary osteochondromas, leaving less available for bone elongation. Due to this uneven distribution of extramedullary lesions around the shafts and in the dual bones of the upper and lower limbs, limb shortening is often accompanied by deformities, such as varus or valgus deformities of the knees, ankles, elbows, and wrists. The most typical deformities occur in the forearm and chest. Since osteochondromas are more common in the wrists than in the elbows, and 3/4 of bone elongation occurs at the distal end of the radius while 4/5 occurs at the proximal end of the ulna, the ulna is always shorter than the radius, resulting in a deformity where the radius protrudes laterally and posteriorly, leading to ulnar deviation, and occasionally radial head dislocation.
Prognosis
Like solitary osteochondromas, multiple hereditary osteochondromas stop growing when growth in the body ceases. If a case of osteochondroma shows significant growth in adulthood, it is usually a sign of sarcomatous transformation, with an incidence of about 25%. Multiple hereditary osteochondromas typically undergo sarcomatous transformation after the age of 15.