enchondroma

Enchondroma is a benign cartilaginous tumor that arises within the medullary cavity of bone. It is most common in the small bones of the hands and feet, but can occur in other bones, including long bones. Most enchondromas are solitary lesions and may remain asymptomatic for years.

Clinical presentation varies. Many lesions are incidental findings on imaging. When symptoms occur, they may include swelling or mild pain, particularly if a fracture or cortical expansion is present. Enchondromas are most often diagnosed in children and adolescents, though they can be found in adults.

Radiographically, enchondromas appear as well-defined lucent lesions within the medullary cavity, often with calcified chondroid matrix that can form rings and arcs. There may be endosteal scalloping and cortical thinning or expansion. MRI and CT aid in assessing the extent and relationships to surrounding structures. Histologically, the tumor shows lobulated nodules of hyaline cartilage with chondrocytes having small, uniform nuclei and minimal mitotic activity, without overt cellular atypia or permeation into surrounding bone.

enchondromas may be associated with more extensive disease in Ollier disease (multiple enchondromas in various bones) or Maffucci syndrome (enchondromas with soft tissue hemangiomas). These conditions carry a higher risk of malignant transformation to chondrosarcoma.

Treatment is typically conservative for asymptomatic solitary lesions. Symptomatic lesions or those causing bone weakness are treated with curettage and bone grafting; extensive or ill-defined tumors may require en bloc resection. Malignant transformation must be distinguished from chondrosarcoma histologically and clinically. Overall prognosis after appropriate treatment is good, though recurrence can occur after incomplete removal.