Osteochondroma, also known as exostosis, is a type of cartilage tumor and is the most common. It can be solitary or multiple, with the solitary form being more prevalent. The multiple form is less common and often associated with skeletal developmental abnormalities, most frequently occurring near the knee and ankle joints. It is typically bilateral and hereditary, hence also called hereditary multiple exostoses. When it occurs near the epiphysis of a bone, it is termed epiphyseal osteochondroma, while those located at the distal phalanx of the toe are called subungual exostoses. Osteochondroma is composed of a fibrous tissue membrane, a cartilage cap, and a bony base. The base can be slender and stalk-like or broad. During the growth period, osteochondroma has its own epiphyseal plate, so its growth ceases when skeletal maturity is reached. Friction between the osteochondroma and surrounding tissues may lead to the formation of a bursa. Approximately 1% of solitary osteochondromas may undergo malignant transformation, whereas the risk increases to 10–20% in cases of multiple osteochondromas, which can develop into chondrosarcoma.

bubble_chart Clinical Manifestations

Most patients are adolescents with a slowly growing bony mass at the site, which is asymptomatic. They often seek medical attention due to functional impairment caused by compression of surrounding tissues such as tendons, nerves, or blood vessels. Multiple osteochondromas can interfere with normal long bone growth and development, leading to shortening and deformities of the affected limb.

bubble_chart Auxiliary Examination

The X-ray findings show that the bone sexually transmitted disease protrudes from the metaphysis and is generally smaller than the clinical observation, as the cartilage cap and bursa are not visible. The bone imaging of the tumor is identical to the bone structure of the metaphysis in its location, making it difficult to distinguish. Tumors located in long bones grow in the direction of traction by adjacent muscles. For example, osteochondromas in the distal femur grow toward the femur, while tumors in the proximal tibia grow toward the distal tibia. Their shapes vary, with some having a long stalk and a narrow base, while others are short and thick with a broad base. Larger tumors may have an expanded tip resembling a cauliflower.

Generally, no treatment is required. However, if the tumor is too large, grows rapidly, or affects function, surgical resection should be considered. The resection should be extensive, including some normal bone tissue around the tumor base to prevent fistula disease and avoid recurrence.