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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.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

button sequestrum

Orthopedics A preserved island of bone–sequestrum lying in a 'punched-out' osteolytic lesion of the diploë of the skull, well-described in eosinophilic granuloma, and seen in infections–TB, staphylococcal infection, metastatic CA, myeloma, radiation necrosis, meningioma, benign bone tumors, and ventriculoatrial shunts.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.