Preoperative difficulties in differentiating intraosseousmeningiomas and fibrous dysplasia around the orbital apex

Intraosseous meningiomas and fibrous dysplasia affecting the roof and apex of the bony orbit may be successfully treated using craniofacial techniques. Although both are usually benign conditions, meningiomas require complete excision to prevent recurrence whereas symptomatic and cosmetic correction of fibrous dysplasia may be achieved with partial removal only in the absence of progressive disease. Differentiating the two conditions is therefore important. Errors in diagnosis due to an excessive reliance on diagnostic imaging have occurred on three occasions in this series of 25 patients. This review evaluates the clinical and investigational features that are most helpful in differentiating the two conditions.