Osteochondroma (Exostosis)

Osteochondroma (Exostosis) is a common benign bone growth that usually develops near the ends of long bones, such as around the knees or shoulders. It involves the skeletal system and appears as a bony bump covered by cartilage. This condition often forms during childhood or adolescence when bones are still growing. Most people with an osteochondroma do not experience symptoms, but it can sometimes cause pain, swelling, or limit joint movement if it presses on nearby tissues. The growth is typically slow and does not turn into cancer. Diagnosis is often made after noticing a painless lump or during imaging for other reasons. Treatment is usually not needed unless the growth causes discomfort or complications.

Osteochondroma (Exostosis) is a benign cartilage-capped bony projection arising on the external surface of a bone, typically near the metaphysis of long bones. It results from an aberrant growth plate cartilage that continues to proliferate and ossify, forming a protrusion composed of both bone and cartilage. This lesion is the most common benign bone tumor and is often solitary but can be multiple in hereditary multiple exostoses caused by mutations in the EXT1 or EXT2 genes. Clinically, it is significant because it can cause mechanical symptoms such as pain, restricted joint motion, or neurovascular compression. Malignant transformation to chondrosarcoma is rare but a critical concern in long-standing or symptomatic lesions. Radiographically, it shows continuity of the lesion’s cortex and medullary cavity with the parent bone, which is a hallmark feature.