Frontal bone epidermoid--a rare cause of proptosis.

Frontal bone epidermoid is a rare condition which may present with proptosis, extraocular muscle imbalance, or loss of vision. Clinically and on plain radiographs an epidermoid may be confused with commoner conditions such as frontal mucocoele. However, the characteristic CT scan appearance, which shows a bone cyst with similar density to brain tissue, should lead to an accurate diagnosis and appropriate surgical management.