Imaging description

Radiographically, an enchondroma in the hand is seen as a geographic lytic lesion. Approximately 50% of the time it will contain calcifications characteristic of a chondroid matrix, with popcorn-like dots, arcs, and whirls (Figure 44.1). Enchondromas can cause visible endosteal scalloping or thinning of the cortex; however, an isolated enchondroma should not have an aggressive appearance. MRI is not indicated usually for enchondromas involving the hand. Pathologic fractures can be a frank, easily seen displaced fracture; however, they may also demonstrate only subtle discontinuity of the cortex on radiographs (Figure 44.2).

Importance

An enchondroma involving the hand should not be painful. If pain is present, then one must carefully look for a subtle fracture (Figure 44.2). If a fracture is not present, then the lesion is not likely to be an enchondroma and further evaluation would be warranted. Pathologic fractures of an enchondroma may not have an antecedent history of trauma, especially if the overlying cortex is fairly thin. Pathologic fractures of enchondromas account for approximately 80% of pathologic fractures in the hand. Most of the fractures occur in the proximal phalanx (approximately 51% of hand pathologic fractures) and in the small finger (approximately 45%).