Pneumosinus dilatans multiplex, mental retardation, and facial deformity.

Pneumosinus dilatans is a term used to describe enlargement of one or more paranasal sinuses without radiological evidence of localized bone destruction, hyperostosis, or mucous-membrane thickening. To date, many cases have been reported that involved frontal, ethmoid, sphenoid, and maxillary sinus. However, no case has been reported that involved all paranasal sinuses. Our case involved mastoid air cells as well as all paranasal sinuses. It is named pneumosinus dilatans multiplex by us. This is the first case to be reported in English literature that has this syndromic condition of pneumosinus dilatans multiplex, mental retardation, and facial deformity.