An 11-year-old previously healthy boy was admitted to hospital with headaches and diplopia. Physical and neurological examinations were normal except for bilateral papilledema and right sixth nerve palsy. Brain CT (Fig. 1) and CT venography were normal. The patient underwent lumbar puncture with an opening pressure of 500 mmH2O, with normal protein and glucose levels, and no cells. Felt to have idiopathic intracranial hypertension (IIH), he was treated with acetazolamide.
Although the patient reported some improvement in headache, papilledema persisted, and 1 month later, MRI of the brain was performed. This study revealed subtle nonspecific signal changes in the right temporal and parietal lobes (Fig. 2). Magnetic resonance venography showed no evidence of venous sinus thrombosis. Another lumbar puncture revealed an opening pressure of 350 mm Hg, with normal cerebrospinal fluid (CSF) content.
Three months later, a second MRI demonstrated diffuse multifocal areas of T2 signal abnormality in the right parietal subcortical white matter and in the right temporal and occipital lobes involving the corpus callosum. These lesions did not enhance following contrast administration.
Five months after initial presentation, a third MRI (Fig. 3) showed progression of the subcortical infiltrative lesions in addition to involvement of the brainstem and superior cervical cord.
The patient underwent an open brain biopsy (Fig. 4) revealing anaplastic cells, which were positive for glial fibrillary acidic protein, and the proliferation marker MIB1 was present in 15%–20% of the cells (World Health Organization grade 3). Necrosis and vascular proliferation were absent. These findings were compatible with anaplastic astrocytoma, and the treatment with whole brain irradiation was initiated.
A number of neoplastic disorders of the central nervous system can mimic IIH. One such example is nonsolid tumor infiltration of the leptomeninges. While this disorder may cause only subtle changes on neuroimaging (1–3), there is often a CSF pleocytosis with elevation in protein. Spinal cord tumors may also mimic IIH but are likely to be evident in imaging (1). The most challenging masquerading lesion is an infiltrative brain tumor that does not cause mass effect, nor influence CSF composition, and may not be detected on initial neuroimaging (1,4). As our case illustrates, this may occur in gliomatosis cerebri (5).
Armstrong et al (6) reported a cohort of 13 pediatric patients with gliomatosis cerebri. The median age at time of diagnosis was 12 years, and 77% of patients were male. The most common presentation was seizure followed by hemiparesis. Only 1 patient reported headache. Frequency of papilledema was not stated, although on neuroimaging 8 patients demonstrated mass effect and 2 had hydrocephalus. Vates et al (7) described 22 patients with gliomatosis cerebri with only 1 in the pediatric age-group (6 years). Papilledema was present in 27% of cases, and in all these patients, there were varying degrees of mass effects on MRI. In contrast, our patient had papilledema without evidence of mass effect on initial neuroimaging. There are few reports of gliomas mimicking IIH. Weston and Lear (5) reported the case of a 44-year-old woman with signs of increased intracranial pressure, including papilledema. Initial brain CT and CSF analysis were normal. Despite undergoing a CSF shunt procedure, the patient continued to deteriorate, and 7 months later, brain MRI showed an infiltrating tumor of the cerebral hemisphere (5) and brain stem. Stereotactic biopsy confirmed the diagnosis of gliomatosis cerebri. Aroichane et al (8) documented the case of a 16-year-old girl on minocycline who presented with headaches for 12 months and diplopia and papilledema for 5 weeks. Brain MRI and CSF were normal, although the authors state that some neuroradiologists felt that there was subtle nonenhancing enlargement of the thalami, optic chiasm, and infundibulum. Eight weeks later, vision declined in the left eye, there was an incomplete bitemporal hemianopia on perimetry, and MRI now revealed a large mass involving the optic chiasm and diencephalon. This proved to be a glioblastoma multiforme.
Similarly, our case serves to emphasize that IIH is a diagnosis of exclusion, and patients must be monitored carefully. After initiating treatment, if neuro-ophthalmic signs and symptoms persist or progress, repeat neuroimaging is mandatory. Even subtle and seemingly nonspecific findings on imaging studies must be closely monitored.
1. Rangwala LM, Grant L. Pediatric idiopathic intracranial hypertension. Surv Ophthalmol. 2007;2:597–617
2. Lipton J, Joffe S, Ullrich NJ. CNS relapse of acute myelogenous leukemia masquerading as pseudotumor cerebri. Pediatr Neurol. 2008;39:355–357
3. Manusow JS, Lee-Wing M, Rahman J, Mis A. Primary leptomeningeal lymphoma masquerading as pseudotumor cerebri. Can J Ophthalmol. 2009;44:e19–e20
4. Said RR, Rosman NP. A negative cranial computed tomographic scan is not adequate to support a diagnosis of pseudotumor cerebri. J Child Neurol. 2004;19:609–613
5. Weston P, Lear J. Gliomatosis cerebri or benign intracranial hypertension? Postgrad Med J. 1995;71:380–381
6. Armstrong GT, Phillips PC, Rorke-Adams LB, Judkins AR, Localio AR, Fisher MJ. Gliomatosis cerebri: 20 years of experience at the Children's Hospital of Philadelphia. Cancer. 2006;107:1597–1606
7. Vates GE, Chang S, Lamborn KR, Prados M, Berger MS. Gliomatosis cerebri: a review of 22 cases. Neurosurgery. 2003;53:261–271
8. Aroichane M, Miller NR, Eggenberger ER. Glioblastoma multiforme masquerading as pseudotumor cerebri. J Clin Neuroophthalmol. 1993;13:105–112