Brain lesions in a case of cystinosis.

Cystinosis usually spares the brain or causes only deposition of cystine crystals without destructive lesions in choroid plexus or, rarely, in brain parenchyma. A case of cystinosis is presented with unusually long survival and with bilateral necrosis, numerous concretions, and extensive demyelination of internal capsule and brachium pontis. No cystine crystals could be demonstrated in these lesions although they were present in the choroid plexus. The symmetry and unique distribution of the lesions as well as their histopathology suggested a progressive process caused by the metabolic dysfunction of cystinosis. The validity of this hypothesis will be determined by future experience as renal transplants enable more patients to survive into adult life.