Is Pseudotumor Cerebri an Actual Tumor?
No, pseudotumor cerebri is definitively not a tumor—it is a syndrome of elevated intracranial pressure without any mass lesion or structural abnormality. The term "pseudotumor" literally means "false tumor" because patients present with symptoms that mimic a brain tumor (headache, papilledema, elevated intracranial pressure), but imaging reveals no actual tumor or mass 1, 2.
What Pseudotumor Cerebri Actually Is
Pseudotumor cerebri, also called idiopathic intracranial hypertension (IIH), is characterized by elevated intracranial pressure of unknown cause without any identifiable intracranial abnormality on neuroimaging 2, 3. The diagnostic criteria specifically require:
- Papilledema 1
- Normal neurological examination 1
- Normal brain parenchyma on imaging—no tumor, no mass, no structural lesion 1, 4
- Normal cerebrospinal fluid composition (no infection, no inflammation) 1, 2
- Elevated lumbar puncture opening pressure (>250 mm H₂O) 1, 4
Why It's Called "Pseudotumor"
The condition mimics a brain tumor clinically because patients experience symptoms of increased intracranial pressure—headache (present in nearly 90% of patients), visual disturbances, papilledema, and sometimes diplopia 5. However, when imaging is performed, MRI reveals normal brain parenchyma without evidence of hydrocephalus, mass, or structural lesion 4. Instead of a tumor, imaging may show secondary signs of elevated pressure such as empty sella, flattened posterior globe, and dilated optic nerve sheaths 4.
The Actual Pathophysiology
The mechanism is likely related to decreased cerebrospinal fluid resorption, causing increased outflow resistance 2, 6. This means intracranial pressure must increase for CSF to be absorbed, but there is no tumor causing this obstruction 6. The condition predominantly affects overweight females of childbearing age, with increasing incidence parallel to the obesity epidemic 5.
Clinical Implications
The main morbidity is visual loss from chronic papilledema, not from any tumor 2, 3. If untreated, papilledema can cause progressive irreversible visual loss and optic atrophy 3. The term "benign intracranial hypertension" should be abandoned because permanent visual impairment can complicate the condition 7.
Treatment focuses on reducing intracranial pressure through weight loss and acetazolamide, not on removing any tumor, because there is no tumor to remove 1, 2.