Morphological diagnosis of Niemann-Pick disease type C by skin and conjunctival biopsies.

Skin and conjunctival biopsies were performed in six children with mental deterioration, incoordination, involuntary movements and discrete visceromegaly. Two main types of inclusions were observed: 1) intracytoplasmic bodies containing membranous profiles loosely disposed in concentric or parallel arrays, lying in clear cells of eccrine sweat glands, hair follicles and cells of the basal layer of skin and 2) pleomorphous membrane bound bodies with a multivesicular aspect which are formed by vacuoles, stacks of lamellae and amorphous electron dense material. Subsequent biochemical studies showing a slight increase of sphingomyelin in liver and normal sphingomyelinase in leukocytes supported the morphological diagnosis of Niemann-Pick disease type C. The qualitative regional diversity of storage is stressed and the interest of both skin and conjunctival biopsies in the diagnosis of this affection is discussed.