Rapidly expanding maxillary pneumosinus dilatans.

Maxillary pneumosinus dilatans is a rare and difficult to diagnose condition at its outset. The natural history of a case where a computer tomography (CT) scan was performed 6 months prior diagnosis raises the possibity that pneumosisnus dilatans and sinus pneumocoele may be a continuum of the same diease process. The classification and aetiology are discussed.