Head injury is very commonly seen in the emergency department (ED) worldwide, and almost, an unenhanced computed tomography scan of the brain suffices for patients seen in the ED presenting after trauma or with a new neurologic deficit. Intracranial lipomas are usually asymptomatic, and they are often an occasional finding. In head injury cases, lipomas are easily to be misdiagnosed as pneumocranium on brain computed tomography with low-density attenuation image. We presented an extremely rare case of interhemispheric lipoma presenting to an ED as a lesion of acute brain insult. The aim of this report is to emphasize the importance of clinical thinking in the differential diagnosis of markedly hypodense lesion on computed tomography imaging of a patient with head injury.