Enchondroma is a benign cartilaginous neoplasm in the medullary cavity. Most enchondromas are
asymptomatic but may present as pathological fractures. Peak age is 10-30 years.
Location:

• Tubular bones (hand, foot): 50%
• Femur, tibia, humerus

Radiographic features:

• Lytic lesion in bones of the hand or foot
• Chondroid calcifications: rings and arcs pattern ("O" and "C")
• Scalloped endosteum
• Expansion of cortex but no cortical breakthrough unless fractured
• No periosteal reaction or soft tissue mass

Pearls:

• In the absence of a fracture, a painful enchondroma is considered malignant until proven otherwise.
• Malignant transformation occurs but is rare.

Enchondromatosis (Ollier disease)

Ollier disease is a nonhereditary abnormality in which multiple enchondromas are present. Many lesions become stable at puberty. Risk of malignant transformation to chondrosarcoma is 25%.

Radiographic features:

• Multiple radiolucent expansile masses in hand and feet
• Hand and foot deformity
• Tendency for unilaterality

Maffucci syndrome

Maffucci syndrome comprises enchondromatosis and multiple soft tissue hemangiomas. Unilateral involvement of hands and feet. Malignant transformation is much more common than in Ollier's disease.