Plexiform neurofibroma of the infra-orbital nerve

Case contributed by Dr Mohammad A. ElBeialy

Presentation

Progressive swelling of the right eye lid since 11 years.

Patient Data

Age: 17 years
Gender: Female

A lobulated and serpentine extra-conal soft tissue mass lesion is seen creeping along the infero-lateral aspect of the right orbit and extending to the right infra-temporal fossa through a widened inferior orbital fissure with associated widening of the foramen rotandum and ptergo-maxillary fissure with possible extension backwards into the pterygopalatine ganglion and its branches within the pterygopalatine fossa. The lesion measures about 5.4 X 2.5 x 4 cm in its maximal axial and cranio-caudal dimensions respectively. It shows heterogeneous intermediate signal in T1 turning into bright signal in both T2 and T2 STIR images with mild homogeneous post-contrast enhancement. The intra-orbital component is seen encroaching upon the intra-orbital fat closely related to inferior aspect of the eye globe with no right orbital proptosis as well as indenting the inferior and lateral recti muscles with no significant displacement.  The lesion extends anteriorly and inferiorly within the right lower eyelid. The infra-temporal component is seen related to the mandibular ramus and lateral pterygoid muscles and shows subcutaneous extension seen superficial to the right masseter as well as the temporalis muscles.

The limited axial T2 and FLAIR study of the brain shows a small focus of bright signal within the the left basal ganglia.  

Normal symmetrical spherical configuration of both eye globes. No left sided intra or extra-conal masses could be detected. Preserved signal with comparable appearance of the left extra-ocular muscles bilaterally with normal course and caliber. Normal MR caliber, course and signal of both optic nerves. No masses seen. Normal MR appearance of the superior ophthalmic veins. No sellar, supra or para-sellar masses. Preserved MR signal of both cavernous sinuses.

Case Discussion

A lobulated and serpentine extra-conal soft tissue mass lesion creeping along the infero-lateral aspect of the right orbit and extending to the right infra-temporal fossa through a widened inferior orbital fissure; most likely representing a plexiform neurofibroma of the infra-orbital nerve with left basal ganglionic small demyelinating lesion is likely unidentified bright object (UBO) related to neurofibromatosis type I (NFI); for clinical correlation and chromosomal analysis / genetic counseling. 

Misdiagnosis of the facial plexiform neurofibroma with venolymphatic malformation is not uncommon.  

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Case Information

rID: 47556
Case created: 21st Aug 2016
Last edited: 23rd Aug 2016
Inclusion in quiz mode: Included

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