Spinal leptomeningeal lymphoma misdiagnosed as IIH

The authors describe two patients with spinal leptomeningeal lymphoma initially misdiagnosed with idiopathic intracranial hypertension (IIH). Neither had clinical signs of a spinal cord or root lesion throughout their clinical course, and good-quality MRIs of the brain and spine initially showed no leptomeningeal enhancement.

In both cases, spinal leptomeningeal lymphoma caused an inexorably progressive pseudotumor syndrome. The authors note that one clue to the correct diagnosis was that the cerebrospinal fluid (CSF) was characterized by high protein, very low glucose and atypical lymphocytes. However, CSF analysis was insufficient to establish the diagnosis.

Contrast-enhanced MRI of the spine eventually showed leptomeningeal and cauda equina nerve root involvement and lead to leptomeningeal biopsy.

The authors say that why IIH develops with spinal tumors and why the ventricles do or do not enlarge is not understood. Proposed mechanisms for IIH include mechanical obstruction, increased CSF protein "clogging" absorption pathways, meningeal inflammation or invasion of the meninges, tumor- secreted products causing arachnoiditis, or changes in craniospinal compliance due to the tumor disrupting the lumbosacral CSF reservoir.

They explain that this report of nonsolid spinal tumors causing IIH appears unique. They propose that in their two patients, involvement of the lumbosacral nerve roots by lymphoma or the grossly elevated spinal CSF protein might have blocked CSF absorption at the spinal level.

They conclude that this paper emphasizes the importance of ordering contrast-enhanced spinal MRI in patients with atypical pseudotumor syndrome.