Enchondroma is a benign cartilaginous tumor arising within the medullary canal of bone, consisting of lobules of mature hyaline cartilage with low cellularity. The lesion likely arises from displaced cartilage rests of the growth plate during skeletal maturation. It accounts for approximately 10% of all benign bone tumors and is the most common benign hand bone tumor.
Distribution: small tubular bones of hand (proximal phalanges most common, 40–60% of solitary enchondromas), proximal humerus, femur (intramedullary, often distal), and tibia. Most are asymptomatic and discovered incidentally on imaging or after pathologic fracture. Symptomatic patients present with pain (particularly with pathologic fracture in hand), local swelling, or restricted motion. Multiple enchondromas occur in Ollier disease (multiple enchondromatosis, sporadic, IDH1/IDH2 mutations) and Maffucci syndrome (multiple enchondromas plus venous/lymphatic malformations), both with significant malignant transformation risk to chondrosarcoma.
Imaging: well-defined lytic lesion in medullary cavity with characteristic chondroid mineralization patterns (stippled, popcorn, ring-and-arc calcifications). Hand enchondromas may show endosteal scalloping; aggressive features include cortical destruction, soft tissue mass, or rapid growth — these warrant evaluation for chondrosarcoma. MRI shows lobulated lesion with bright T2 signal (cartilage water content). Differentiating enchondroma from low-grade chondrosarcoma can be challenging and requires correlation of radiographic features, location, size, growth pattern, and clinical findings. Treatment: observation for asymptomatic small enchondromas with serial imaging. Curettage with bone grafting (autograft, allograft, synthetic) for symptomatic, pathologic fracture, growing lesion, or atypical features. Wide resection for aggressive low-grade chondrosarcoma confused with atypical enchondroma. Surveillance and multidisciplinary management for Ollier and Maffucci patients.