[An unusual case of non-traumatic enophthalmos].

An extensive spectrum of differential diagnoses has to be considered when a patient presents with enophthalmos. The most common causes of this presentation include orbital trauma or contraction and atrophy of the orbital contents secondary to scleroderma or radiotherapy. However radiologists also have to consider less common causes of enophthalmos, such as the imploding antrum syndrome or the ethmoid silent sinus syndrome. The latter involves the ethmoidal cells and results in medial orbital wall implosion. Along with the case presentation the pathogenesis, incidence and differential diagnoses of ethmoid silent sinus syndrome are elucidated. In particular the differentiation from normal anatomical variants, such as dehiscent lamina papyracea is discussed.