enchondromas

Enchondromas are benign cartilaginous tumors that develop within the medullary cavity of bones. They are most commonly diagnosed in children and young adults and are often discovered incidentally. The most frequent locations are the small bones of the hands and feet, but enchondromas can occur in long bones such as the femur, humerus, or tibia.

Most solitary enchondromas are asymptomatic. They may be found after a fracture or, less commonly, because of slowly enlarging pain or swelling. When symptomatic, symptoms relate to bone weakening, cortical thinning, or mass effect. In rare cases, large lesions can cause deformity.

Radiologic and histologic features aid diagnosis. On radiographs, enchondromas appear as well-defined, lucent intramedullary lesions with chondroid calcifications (rings and arcs), often with endosteal scalloping and mild cortical thinning. MRI typically shows a lesion with high signal intensity on T2-weighted images consistent with cartilage. Histology reveals mature hyaline cartilage nodules with chondrocytes in lacunae; features that suggest malignancy include permeative growth, significant cellular atypia, or invasion of surrounding tissues, which would raise concern for chondrosarcoma.

Management depends on symptoms, location, and patient age. Solitary, asymptomatic enchondromas may be observed. Symptomatic lesions, growing lesions, or those at risk of fracture are usually treated with intralesional curettage and bone grafting or bone substitutes. In long bones, adjuvants (e.g., phenol, cryotherapy) may be used in selected cases. Enchondromas can be solitary or part of syndromes such as Ollier disease (multiple enchondromas) or Maffucci syndrome (enchondromas with vascular malformations), which carry a higher risk of malignant transformation to chondrosarcoma.

Prognosis is generally excellent for solitary enchondromas after complete curettage or observation, with recurrence being uncommon.