Adult onset Niemann-Pick disease type C presenting with dementia and absent organomegaly.

A 39-year-old female presented to the Bryan Memory Disorders Clinic at Duke University with a 7-year history of an atypical progressive dementia, mildly impaired vertical gaze, dysarthria and mild ataxia. There was no evidence of organomegaly by clinical examination or by radionuclide liver/spleen scan. Brain biopsy disclosed a neuronal storage disorder characterized by ballooned neurons filled with oligo-lamellar cytosomes and lipid droplets. Cultured skin fibroblasts had diminished sphingomyelinase activity and impaired cholesterol esterification, although peripheral leukocyte sphingomyelinase activity was normal. Two years after biopsy, follow-up examination revealed marked progression of vertical gaze paralysis and ataxia. This case expands the clinical spectrum of Niemann-Pick disease type C by presenting in adulthood with subtle neurologic abnormalities; no visceromegaly and profound dementia.