May Be Caused by

 Common

Avascular necrosis

Bone infarct

Brodie abscess

Button sequestrum in skull

Osteoid osteoma

Osteomyelitis

 Uncommon

Fibrosarcoma

Langerhans cell histiocytosis

Lymphoma

Malignant fibrous histiocytoma

Metastasis

Osteoblastoma

Syphilis

Tropical ulcer

Tuberculosis

Yaws