Eosinophilic granuloma

• Form of histiocytosis X
• Rare in >30 y/o
• May or may not have sclerotic border and may or may not elicit periosteal response
• Occasionally has bone sequestrum
  • Along with osteomyelitis, lymphoma, and malignant fibrous histiocytoma (includes fibrosarcoma and desmoids)

Discriminator

• Must be under age 30 (over 30 is rare but not impossible)