Micrograph of an<unk> . H&E stain. Histologically, they are classified in two variants. * The classic (or standard) form (95%) has blood filled clefts among bony trabeculae. Osteoid tissue is found in stromal matrix. * The solid form (5%) shows fibroblastic proliferation, osteoid production and degenerated calcifying fibromyxoid elements. According to Buraczewski and Dabska, the development of the<unk>  follows three stages. Stage Description Initial phase (I) Osteolysis without peculiar findings Growth phase (II) * Rapid increase in size of osseous erosion * Enlargement of involved bone * Formation of shell around central part of lesion Stabilization phase (III) Fully developed radiological pattern They can also be associated with a TRE17/USP6 translocation.<unk> s may be intraosseous, staying inside of the bone marrow. Or they may be extraosseous, developing on the surface of the bone, and extending into the marrow. A radiograph will reveal a soap bubble appearance.
Aneurysmal bone cyst
Bone cyst
Osteoid osteoma
Unicameral bone cyst
Juvenile active ossifying fibroma
Osteoma
Osteochondroma
Peripheral ossifying fibroma