Ethmoidal pneumocele following drainage of an ethmoidal mucocele.

Ethmoidal pneumocele is a rare condition with little known about its etiology. We report a 5-year-old boy who had recurrent right orbital cellulitis, non-axial proptosis, and inferolateral globe displacement. Initial radiological investigations demonstrated an ethmoidal mucocele. There was complete resolution of inflammatory signs with endoscopic drainage of the mucocele; however, repeat CT revealed a residual pneumocele with continued proptosis and lateral displacement of the globe. This case illustrates the potential for chronic sinusitis and iatrogenic drainage of an ethmoidal mucocele to progress to a pneumocele.