Since brain biopsy as a means of achieving a correct antemortem diagnosis of a progressive neurodegenerative disease in childhood has largely been abandoned, the neuropathologist has resorted to studying non-neural tissues instead. Due to the fact that almost any progressive neurodegenerative disease of childhood that can be reliably recognized by brain biopsy can also be safely diagnosed in non-neural tissues, these diagnostic achievements from non-neural tissues rendered brain biopsy obsolete. The skin/conjunctiva is the tissue most suited for such in vivo diagnostic investigations while studies of other non-neural tissue such as circulating lymphocytes, rectum, peripheral nerves, skeletal muscle, and liver play only a minor role. The cytological wealth in skin specimens provides morphological information, largely based on electron microscopy, in numerous lysosomal and quite a few non-lysosomal neurodegenerative diseases of childhood.

Keywords: biopsy, diagnosis, neurogenerative disorders, skin, ultrastructure