Leptomeningeal involvement in hereditary transthyretin (TTR) amyloidosis

47-year-old male with hereditary transthyretin cardiac amyloidosis presenting with hydrocephalus, status post-CSF diversion. T1-weighted post-contrast coronal (A), sagittal (B), and axial (C) MRI sequences show diffusely abnormal leptomeningeal enhancement involving cortex, brainstem, and cerebellum. Lumbar CSF was acellular and protein was elevated (243 mg/dL).