|Ahead of print
Optic nerve glioma in neurofibromatosis: Radiological clues to diagnosis in a young child
Harsh Patel1, Biswaroop Chakrabarty1, Rachna Dubey1, Atin Kumar2, Sheffali Gulati1
1 Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India
2 Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India
|Date of Submission||18-Jul-2020|
|Date of Decision||03-Oct-2020|
|Date of Acceptance||28-Oct-2020|
|Date of Web Publication||12-Jul-2021|
Centre of Excellence and Advanced Research on Childhood Neurodevelopmental Disorders; Division of Child Neurology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi.
Source of Support: None, Conflict of Interest: None
| Abstract|| |
A 13-month-old boy presented with delay in attainment of milestones. On examination, he had café au lait spots and central hypotonia. MRI brain with contrast revealed bilateral bulky enhancing optic nerves with involvement of chiasma. Mid-orbit downward kinking and pseudo-cerebrospinal fluid sign classical of optic nerve glioma (OPG) with neurofibromatosis1 (NF1) could be well appreciated in the MRI. Correct identification of OPG may help in the diagnosis of NF1 in a young child, as other phenotypic features appear later in childhood.
Keywords: Double-intensity tubular thickening, mid-orbit downward kinking, neurofibromatosis 1, optic nerve glioma
A 13-month-old boy presented with global developmental delay without impaired vision or hearing or any abnormal movements. His antenatal, neonatal, and family histories were unremarkable. Salient features on examination were multiple café au lait spots and non-paralytic axial hypotonia. His ophthalmological examination did not reveal lisch nodules or any other abnormality. His MRI brain with contrast showed bilaterally enhancing, bulky, and tortuous optic nerves involving optic chiasma. A mid-orbit downward kinking and double-intensity tubular thickening (pseudo-cerebrospinal fluid sign) could be appreciated bilaterally as described classically with optic nerve glioma (OPG) characteristic of NF1 [Figure 1] and [Figure 2].
|Figure 1: T2W (A,B) and post-contrast T1W (C,D) axial MR images show tortuous and enlarged bilateral optic nerves with enlarged optic chiasma (arrows in B) demonstrating marked enhancement on post-contrast images. There is mid-orbit downward kinking of optic nerves (yellow arrows) and double-intensity tubular thickening (hyperintense and hypointense rim surrounding the optic nerve on T2- and T1-weighted images, respectively, represented by red arrows indicating the pseudo-cerebrospinal fluid or the double-intensity lumen sign).|
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|Figure 2: T2W coronal image (A) shows bilateral enlarged and hyperintense optic nerves (arrows). T2W sagittal image (B) better shows the tortuosity of the enlarged optic nerve.|
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Bilateral presence, preferential pre-chiasmatic and chiasmatic affliction, mid-orbit downward kinking, and pseudo-cerebrospinal fluid sign characterize OPGs in NF1. The pseudo-cerebrospinal fluid sign is seen secondary to perineural arachnoid gliomatosis (PAG) peripheral to the optic nerve., The optic nerve gliomas classically exhibit two patterns of growth, intraneural and perineural. The intraneural pattern causes fusiform enlargement of the nerve, and PAG causes subarachnoid astrocytic proliferation around the optic nerve. The current case shows both patterns of tumor growth, highlighting the classical radiological features of OPG in NF1.
The presence of OPG is a definitive diagnostic criterion for NF1. Identification of OPG along with café au lait spots helped in diagnosing NF1 in this young child. Other easily recognizable diagnostic features of NF1, such as axillary and inguinal freckling, lisch nodules, neurofibromas, and bony deformities, usually appear beyond 5 to 6 years of age.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]