Cranio-orbital-temporal neurofibromatosis: An uncommon subtype of neurofibromatosis type-1.

Introduction

Neurofibromatosis is a multisystem genetic disorder that is commonly associated with cutaneous, neurologic, ophthalmic, and orthopedic manifestations. The National Institute of Health has given the diagnostic criteria for neurofibromatosis type 1(NF1).[1] Cranio-orbital-temporal neurofibromatosis is an uncommon subtype of NF-1 and is characterized by pulsatile exophthalmos, orbital neurofibromas, sphenoid wing dysplasia, expansion of the temporal fossa, and herniation of the temporal lobe into the orbit.[2] One such rare case of cranio-orbital-temporal neurofibromatosis with hemimegalencephaly is reported here.

Case Report

An 11-year-old girl presented to us with history of painless, gradually progressive protrusion of the left eye with diminution of vision and whitish discoloration of that eye since 3 years.

On examination of right eye (OD)-best corrected visual acuity was 6/6. Slit lamp examination revealed normal cornea with multiple Lisch nodules [Figure 1] distributed all over the iris. Gonioscopy showed open angles in all quadrants. Fundus evaluation was normal. Intraocular pressure was 12 mm Hg with Perkins applanation tonometry.

Figure 1

Slit lamp photograph showing Lisch nodules

Visual acuity in left eye (OS) was no perception of light. Uppereyelid revealed an ill-defined nodular swelling measuring 4 × 2 cm, which on palpation was soft in consistency, compressible, and pulsatile. On auscultation, no bruit was heard over the swelling. An eccentric proptosis with vertical displacement of 20 mm and horizontal displacement of 30 mm was noted. Exposed interpalpebral area revealed congested and chemosed conjunctiva with keratinized cornea [Figure 2]. Extraocular movements were restricted in all directions of gaze.

Figure 2

Clinical photograph showing swelling of upper lid (LE) and eccentric proptosis of left eye with keratinized cornea

On systemic examination, scoliosis and multiple café-au-lait spots over her abdomen and back were present.

X ray skull revealed a well-defined osteolytic lesion in the left frontoparietal region with ‘bare orbit sign,[3]-absence of innominate line in left orbit which is the projection of the greater wing of the sphenoid bone [Figure 3]. This is a sign of sphenoid wing dysplasia. There was enlargement of the anterior orbital rim and a bony defect in the posterosuperior orbit.

Figure 3

X ray skull showing osteolytic lesion in the left frontoparietal region (arrow) and “bare orbit” sign (absence of projection of greater wing of sphenoid bone in left orbit)−solid arrow. Note the enlargement of anterior orbital rim

Magnetic resonance imaging (MRI) of orbit and brain revealed dysplasia of the greater wing of the sphenoid bone of left side with gross thinning and scalloping of outer and inner tables of anterior squamous temporal bone. There was herniation of brain tissue through the bony defect into the orbit causing proptosis [Figure 4]. Left eyeball was compressed with presence of dystrophic changes. Gross asymmetrical ventriculomegaly with hemimegalencephaly (ipsilateral enlargement of the hemicerebrum) of left side brain [Figure 5] was noted. Histopathology (HPE) report of a biopsy taken from a cutaneous swelling revealed benign peripheral nerve sheath tumor.

Figure 4

Magnetic resonance imaging of orbit and brain showing dysplasia of the greater wing of the sphenoid bone of left side with herniation of brain tissue through the bony defect into the orbit causing proptosis

Figure 5

Magnetic resonance imaging of brain showing gross asymmetrical ventriculomegaly with hemimegalencephaly (ipsilateral enlargement of the hemicerebrum) of left side brain

On eliciting family history, patient's mother had multiple cutaneous neurofibromas over the face and back with Lisch nodules and prominent corneal nerves.

Discussion

This patient was diagnosed as a case of cranio-orbital-temporal neurofibromatosis which is an uncommon subtype of NF-1, characterized by pulsatile exophthalmos, orbital neurofibromas, sphenoid wing dysplasia, expansion of the temporal fossa, and herniation of the temporal lobe into the orbit.[24] She had hemimegalencephaly which is very rare to occur in NF-1 patients.[5] Her parents denied any surgical intervention when the prognosis was explained to them.

Conclusion

Patients with orbital NF-1 present with varied orbital and cranial lesions. A through systemic examination with MRI scanning of orbit and brain helps in diagnosis and management. Genetic counseling is important in these patients because of almost 100% penetrance, each child of an affected individual has 50% chance of developing the disease.[6]