Nationwide epidemiologic study of osteochondroma in Japan: Analysis of 4843 cases from the bone and soft tissue tumor registry

Osteochondroma is the most common benign bone tumor; however, large-scale epidemiologic data remain limited, particularly in Asian populations. This nationwide registry-based study aimed to clarify the epidemiology and clinical characteristics of osteochondroma in Japan. Patients diagnosed with osteochondroma between 2006 and 2019 were identified from the Bone and Soft Tissue Tumor (BSTT) Registry of the Japanese Orthopaedic Association. Demographics, tumor location, subtype (solitary osteochondroma [SO] vs. multiple osteochondroma [MO]), and surgical history were analyzed, and comparisons between SO and MO were performed using χ² and Mann-Whitney U tests. A total of 4,843 patients (2,911 males and 1,932 females; male-to-female ratio, 1.5:1) were included. SO accounted for 77.1% and MO for 22.9% of cases. The median age at diagnosis was 15 years, and nearly half of all patients were younger than 20 years. The lower limb was the most frequently affected region (65.2%), followed by the upper limb (26.3%) and pelvis (4.5%), with the femur and tibia being the most common sites. MO presented at a significantly younger age and exhibited characteristic symmetric involvement of multiple long bones, particularly in the lower extremities and forearms. Surgical intervention was more common in SO than in MO (49.9% vs. 37.9%, p < 0.001). This study provides the largest epidemiologic overview of osteochondroma in Japan and highlights distinct clinical patterns between SO and MO, offering essential population-based evidence to guide future clinical management and surveillance strategies in Asian populations.