Nasu-Hakola disease (Orphanet_2770, an Orphanet rare-disease nomenclature entry) (NHD), also referred to as polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL), is a rare inherited leukodystrophy characterized by progressive presenile dementia associated with recurrent bone fractures due to polycystic osseous lesions of the lower and upper extremities. Also known as: NHD, PLO-SL, PLOSL, Polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy.