Abstract
Encephaloceles are uncommon lesions, most of which are congenital, and may be overlooked in routine radiologic practice. Failure to identify a skull base defect and characterize the herniated contents may delay recognition of associated abnormalities and clinically important complications, including cerebrospinal fluid leakage, intracranial infection, intracranial hypotension, hydrocephalus, and seizures. Granulomatosis with polyangiitis can cause destructive sinonasal disease with extension to the skull base; however, a meningoencephalocele in this setting is exceptionally rare. We report a 58-year-old woman with longstanding granulomatosis with polyangiitis who presented with new-onset seizures. Computed tomography and magnetic resonance imaging demonstrated a right transethmoidal meningoencephalocele through an ethmoidal roof defect contiguous with extensive destructive sinonasal changes, with encephalomalacia and gliosis of the herniated brain parenchyma.