From the Guidelines
Osteochondroma is a benign bone tumor that develops during childhood or adolescence, consisting of a bony growth covered by a cartilage cap that forms on the outer surface of a bone, typically near the growth plate of long bones, with a small risk of malignant transformation into chondrosarcoma.
Key Characteristics of Osteochondroma
- Most osteochondromas are solitary lesions, though some patients have multiple tumors in a condition called multiple hereditary exostoses, which is inherited in an autosomal dominant pattern 1.
- These tumors usually stop growing when skeletal maturity is reached, but can cause pain if they compress nearby nerves, blood vessels, or tendons.
- Treatment is often unnecessary unless the tumor causes symptoms, interferes with joint function, or shows concerning growth after skeletal maturity, as evidenced by rapid growth, increasing pain, and/or a bulky cartilage cap that is thicker than 2.0 to 3.0 cm on an MRI or CT scan, which suggests progression to chondrosarcoma 1.
Surveillance and Management
- Annual physical examinations starting in childhood with early investigations in case of increasing pain or rapid growth of lesions are recommended, along with considering a baseline skeletal survey at early adolescence (around 12 years) when most osteochondromas have evolved and before the age of transformation risk 1.
- Regular regional MRI (every 2–3 years) of osteochondromas identified in the pelvis or scapula may be valuable, as transformation is more common in these locations, particularly in males or EXT1 PV carriers 1.
- Orthopedic providers should preferably be involved in the monitoring of osteochondromas, and care should be taken in an academic center, with expertise in rare syndromes or syndromes of bone lesions 1.
From the Research
Definition and Characteristics of Osteochondroma
- Osteochondroma is a benign bone tumor, commonly seen as a bony outgrowth from the metaphysis of long bones, having a stalk and cartilage cap 2, 3, 4.
- It may be sessile or multiple and usually arises before 20 years of age with no growth beyond puberty 2.
- Osteochondroma is the most common benign bone tumor and usually occurs in the metaphyseal region of the long bones 4.
Clinical Presentation and Symptoms
- Although often asymptomatic, symptoms may eventuate from compression of adjacent vessels or nerves, fractures, osseous deformities, bursa formation, or malignant transformation 3.
- Painful lesion due to mechanical interaction or pressure on nearby neurovascular bundle, or from inflamed bursa, growth disturbances of the fellow bone, neurological symptoms, and vascular complications are possible local effects of osteochondroma 5.
Malignant Transformation and Treatment
- Malignant transformation is a rare complication seen in 1% of solitary cases and 3-5% in the hereditary multiple enchondromatosis variety 2.
- Cartilage cap thickness >2 cm in adults or >3 cm in children as well as new onset of pain or growth, or rapid growth of the lesion, especially after the closure of the growth plate, might reflect cancerous transformation 3, 6.
- Surgical resection is indicated for symptomatic lesions, complications, cosmetic reasons, or malignant transformation, and excision of the tumor with free margin is the treatment of choice 3, 5.