To report a 73-year-old man with tension pneumocephalus (TP) after glioblastoma multiforme resection diagnosed by the Mount Fuji sign.

The presence of pneumocephalus after neurosurgical procedures or head trauma is not uncommon and typically reabsorbs on its own. Occasionally, there is an increase in intracranial pressure leading to TP which represents an emergency, if untreated it may lead to cerebral herniation and death.

A 73-year-old man with a history of left temporal glioblastoma multiforme underwent resection of his tumor and presented three days later with syncopal episode and lethargy. 

Head computed tomography (CT) scan revealed tension pneumocephalus which was evident by the presence of air between the tips of the frontal lobes known as the Mount Fuji sign. He was treated with 100% oxygen supplementation with subsequent clinical and radiological improvement. 

Our case highlights the importance of considering tension pneumocephalus as a postoperative complication in a patient with acute neurological deficits as well as recognizing the Mount Fuji sign in brain imaging for a prompt diagnosis and treatment.