Bare orbit sign, is described as a characteristic appearance of orbit, where the innominate line is absent. The innominate line is a projection of the greater wing of the sphenoid, and its absence or destruction is responsible for this appearance.
It is the classical frontal radiograph sign of neurofibromatosis type I (NF1). In addition to bare orbit sign, it is accompanied by egg shaped enlargement of anterior orbital rim, bony defect in posterior orbit and anteroposterior enlargement of middle cranial fossa.
Bare orbit sign may also be seen in destruction of sphenoid wing, most commonly in neuroblastoma metastases.
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- Sherwani P, Faizi NA, Anand R et-al. Bare orbit sign: classical sign in cranio-orbital-temporal neurofibromatosis 1. Indian J Pediatr. 2015;82 (2): 203-4. doi:10.1007/s12098-014-1564-7 - Pubmed citation