button sequestrum sign

button sequestrum sign

A radiologic finding consisting of a rounded island of sclerotic bone—the so-called sequestrum—lying in a “punched-out” osteolytic lesion of the diploë of the skull, hip or elsewhere; first described in eosinophilic granuloma, but also seen in osteomyelitis, infections (TB, staphylococcal infection), metastatic cancer, multiple myeloma, radiation necrosis, meningioma, benign bone tumours and ventriculoatrial shunts.