Computed tomography and plain film appearance of a bony sequestration: significance and differential diagnosis.

Bony sequestration has been reported in osteomyelitis, eosinophilic granuloma, and fibrosarcoma. Thirty-eight examples of radiographically apparent bony sequestra were collected to examine the validity of this differential diagnosis. Apparent sequestra were found in osteomyelitis (59%), fibrosarcoma or fibrosarcoma-like entities (13%), eosinophilic granuloma (8%), and osteoid osteoma (21%). Although osteoid osteoma does not contain a true bony sequestrum, the partially calcified nidus was radiographically mistaken for a sequestrum in eight (21%) of our cases and, therefore, should be considered when an apparent sequestrum is visualized. Computed tomography enhanced visualization of a sequestrum in 19 of 22 cases and is recommended as an adjunct to conventional radiography when the presence of a sequestrum will alter therapy.