The association of unilateral, rapidly progressive hearing loss, tinnitus and vestibular dysfunction in combination with a contrast-enhancing mass within the internal auditory canal on MRI is suggestive of a vestibular schwannoma (VS). We report the rare finding of a HIV-associated cerebral lymphocyte infiltration, most probably malignant lymphoma, which was presumed initially to be a VS. A 36-year-old male presented with progressive unilateral hearing loss accompanied by acute, ipsilateral tinnitus. Interpreted first as sudden sensorineural hearing loss, his symptoms were treated with rheologic therapy. Ipsilateral facial palsy appeared. MRI with gadolininium disclosed a contrast-enhancing mass within the internal auditory meatus of the left side. Within five weeks an extended leptomeningeal lymphocyte infiltration evolved and the diagnosis of an underlying HIV infection was made. Unilateral, rapidly progressive hearing loss and a fast growing cerebello-pontine mass is atypical for VS and highly suspicious of malignant disease. To our knowledge we report the first case of an HIV-associated cerebral lymphocyte infiltration, mimicking a VS. In such cases the diagnostic work-up should include a HIV test.