Angulate lysosomes in skin biopsies of patients with degenerative neurological disorders: high frequency in neuronal ceroid lipofuscinosis

Angulate lysosomes with intralysosomal trilamellar structures were first de scribed in patients with metabolic peroxisomal disorders. In this ultrastru ctural study of skin biopsies of 139 patients with degenerative neurologica l disorders and 45 patients with static encephalopathies, we observed angul ate lysosomes with similar ultrastructure exclusively in degenerative neuro logical disorders. They were found in only a few cases (8%), but especially in patients with degenerative metabolic disorders (72%). Because they were never observed in patients with static encephalopathies, angulate lysosome s in the skin would seem to be a sign of progressive encephalopathy. The gr eat majority (75%) of angulate lysosomes were associated with neuronal cero id-lipofuscinosis (NCL). Their presence in skin biopsy could suggest the di agnosis of NCL and eliminate a peroxisomal disorder. In the latter patholog y, angulate lysosomes, numerous in the liver and in the brain, were never o bserved in the skin. As described in pigmentary retinopathy, a conspicuous feature of NCL, we suggest that in this lysosomal storage disorder, the ang ulate lysosomes in skin biopsies could result from the phagocytosis of mela nin.