Non-epithelial cysts (not true cysts)

Solitary bone cyst

Radiology

The solitary bone cyst appears as a well-defined but non-corticated radiolucency. Typically, it has little effect
on adjacent structures and 'arches' up between the roots of teeth .

The inferior dental canal may not be displaced, but the cortical margins of the canal may be lost where it overlies the lesion. Expansion is rare.

Pathology

The cyst is lined by fibrovascular tissue that often includes haemosiderin and multinucleate giant cells.

Aneurysmal bone cyst

Radiology

The aneurysmal bone cyst typically presents as a fairly well-defined radiolucency. Sometimes it has a multilocular appearance because of the occurrence of internal bony septa and opacification. Marked expansion is a feature.

Pathology

The predominant feature of an aneurysmal bone cyst is the presence of blood-filled spaces of variable size lying in a stroma rich in fibroblasts, multinucleate giant cells and haemosiderin. Deposits of osteoid are also seen