Codman triangle
A triangular area of new bone formation at the edge of a bone lesion, visible on radiographs as a sign of aggressive bone pathology.
Full Definition
A Codman triangle is a radiographic sign consisting of a triangular shadow of new bone formation that appears when periosteum is elevated from underlying cortical bone by an expanding lesion. Named after surgeon Ernest Codman, this finding represents the periosteum's attempt to lay down new bone at the edge of a rapidly growing lesion. The triangle forms where the elevated periosteum meets the normal cortex. While often associated with malignant bone tumors, Codman triangles can also occur with benign but aggressive lesions, infections, or trauma. The finding indicates rapid growth that outpaces the periosteum's ability to form continuous reactive bone.
Usage
Usage note: Named finding; capitalize 'Codman' but not 'triangle'.
In Context
- "Radiographs demonstrated a Codman triangle at the proximal aspect of the lesion." — Radiology report
- "The presence of a Codman triangle suggested an aggressive process requiring urgent evaluation." — Orthopedic consultation note