Pseudotumors and Reactive Lesions

This article discusses reactive or degenerative processes in bone or periosteal soft tissue that occasionally masquerade as neoplasms. Presentation of the clinical, radiologic, and pathologic features of these processes is provided with an emphasis on the avoidance of overdiagnosis. Clinical, radiologic, and pathologic features of pseudotumors are presented in detail. This article approaches these tumor-like lesions in 2 categories: (1) those in the soft tissue next to bone and (2) those inside bones from the aspect of mineralization and calcification.