Absence of a Sphenoid Wing in Neurofibromatosis Type 1 Disease MDCT scan, performed at the level of the orbit, revealed the absence of the right sphenoid wing, right eye microph- thalmos, increased fat tissue in the retrobulbar space and an enlarged middle cranial fossa. Furthermore, the left globe was larger than the right (Fig. 2C). DISCUSSION Neurofibromatosis type 1 may affect all systems of the human body. It is a hamartomatous disorder that originates in the neural crest and secondarily affects the supporting mesenchyme. The disorder, which is characterized by pigmented cutaneous lesions and generalized tumors that originate in the neural crest (taking the form of a discrete fibroma nodule or a plexiform neurofibroma), manifests itself in various ways. Central nervous system indicators consist of an increased incidence of astrocytomas, Fig. 1. Physical examination revealed a normotensive man with cafe-au-lait spots on his chest and abdomen. meningiomas, schwannomas, and ependymomas. Other features of the disease include bony dysplasias, kyphoscol- iosis, sphenoid wing hypoplasia and vascular dysplasia. Sphenoid dysplasia is one of the characteristics of NF-1, occurring in 5 10% of cases. Furthermore, abnormalities of the sphenoid wings are often considered pathogno- monic. However, complete dysgenesis of the sphenoid wing is very rare (1 4). Its radiological characteristics describe the area of defect in the greater sphenoid wing and enlargement of the middle cranial fossa. Many ophthalmic manifestations may occur in NF-1 patients. Lisch nodules are virtually all pathognomonic, and Huson et al. (5) found these iris hamartomas to be present in all of his NF-1 patients over the 16 years of age. Other ophthalmic findings include choroidal hamartomas, plexiform neurofibromas, retinal phakomos and optic nerve gliomas. Exophthalmos and enophthalmos, potential sequelae, are associated with orbital tumors and/or sphenoid wing dysplasia (1, 6). Unilateral enophthalmos, primarily viewed as a compli- cation of an orbital fracture, may result from other causes such as microphthalmos, orbital fibrosis, and sclerosing orbital tumors (1, 3). Congenital microphthalmia occasion- aly accompanies sphenoid dysplasia or similar sphenoidal abnormalities. The neuro-ophtalmological findings of NF-1 are variable, pulsating exophthalmos is a common one. However, in a few cases in which NF-1 patients have sphenoid dysplasia, enophthalmos was also seen as a result of microphthalmia or because the lateral wall of the orbit was deficient and allowed decompression of the neurofi- bromatous tissue or retrobulbar fat into the temporal fossa (7). The present case had NF-1 with sphenoid wing dysgen- esis leading to enophthalmos, but neurofibroma was not A B C Fig. 2. A. Anterior volume rendered 3D CT image illustrates details of the bony defect in the right orbital region. B. Thick multiplanar axial reconstructions illustrates the absence of the right sphenoid wing and the intracranial and orbital contents separated only by dura mater. C. Transverse bone window multidetertor CT scan, performed at the level of the orbit, illustrates the absence of the right sphenoid wing, right eye microphthalmos, increased fat tissue in the retrobulbar space and enlarged middle cranial fossa. The left globe is larger than the right. Korean J Radiol 7(1), March 2006 71