Intraosseous lipoma. A clinicopathologic study of four cases.

We describe the clinical, radiologic, and pathologic features of four cases of intraosseous lipoma. The patients ranged in age from 37 to 48 years, and three of them were men. Three patients presented with pain; in the fourth patient, the lesion was discovered incidentally. The involved bones were distal radius (in one patient), humerus (in two patients), and calcaneus (in one patient). In all cases, plain films revealed well-defined lytic lesions. Computed tomographic scan in all cases, and magnetic resonance imaging in one case, showed the lesions to have attenuation values and signal intensity identical to adipose tissue. Histopathologic examination of the curetted lesions revealed mature adipose tissue devoid of hematopoietic elements. Dystrophic calcification was present in two cases, necrosis of fat in one case, and extensive recent and remote hemorrhage in another case. As the roentgenographic differential diagnosis can be extensive, familiarity with this entity is important. These cases emphasize the characteristics of intraosseous lipoma, and they highlight the need for clinicopathologic and roentgenographic correlations.