Pneumosinus dilatans with shift of midline intracranial structures: A case report.

Pneumosinus dilatans (PSD) is an abnormal dilatation and enlargement of one or more paranasal sinuses, extending beyond the anatomic bony boundaries, without defect or thinning of its bony walls. It is documented by only a few reports. Usually asymptomatic, it is in general found incidentally on imaging.