Blade of Grass
"Flame Sign" - Paget Disease

General Considerations

• V-spaded lucency in the metadiaphysis, usually seen in a long bone and representing the lytic phase of Paget disease
• Most often seen in femur and tibia
• In the skull, the lytic defect is referred to as osteoporosis circumscripta, most often seen in the frontal bone

Clinical Findings

• Usually asymptomatic

Imaging Findings

• Seen usually in the axial and appendicular skeleton
• The most common findings in Paget disease are in the later, sclerotic phase and include
  • Thickening of the cortex
  • Accentuation of the trabecular pattern
  • Enlargement of the affected bone
  • Increase in density but decrease in overall strength of involved bone

Blade-of-grass sign. V-shaped lucency (white arrow) in metaphysis of femur from the lytic phase of Paget disease.
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