Male, 78 years old, with acoustic neuroma and hearing loss, status post radiosurgery and 4/17/2015. A tumor is redemonstrated involving the left internal auditory canal and extending into the left cerebellopontine angle cistern. The lesion is stable or at most 1 mm larger in some dimensions. However, the lesion shows less intense internal enhancement and contains areas of T2 hypointensity and susceptibility suggesting hemosiderin staining.No additional intracranial enhancing lesions are seen. No restricted diffusion is detected. Patchy periventricular and subcortical white matter T2 hyperintensity is redemonstrated appearing similar to the prior examination. No abnormal extra-axial collections are observed. There is no evidence of acute intracranial hemorrhage. The ventricles and sulci are slightly prominent compatible with underlying parenchymal volume loss.Bone marrow signal characteristics are within normal limits. Chronic mucosal thickening or a mucous retention cyst is again seen within the right sphenoid sinus. Minimal mucosal thickening is seen within the maxillary sinuses.
A tumor is redemonstrated involving the left IAC and CP angle cistern compatible with a vestibular schwannoma. Since the prior examination, this lesion is stable or at most 1 mm larger. It does, however, show less intense internal enhancement and appears to have developed internal hemosiderin staining. These findings could very well reflect the effects of radiosurgery. Continued follow-up is advised.