Unique astrocytic inclusion in a 2 month-old baby showing Leigh-like brain lesions with lactic acidosis

An unique cytoplasmic inclusion was found in astrocytes of a 2-month-old female baby who showed Leigh-like brain lesions with lactic acidosis, hypoglycemia and hepatomegaly. Although a defective enzyme was not determined, a metabolic disorder was suggested from clinicopathological observations. Symmetrically distributed lesions consisting of marked gliosis and proliferation of capillaries were observed in the basal ganglia, thalami and tegmentum. The astrocytic cytoplasmic inclusion was exclusively found in the cerebral and cerebellar white matter, where myelination was immature. The inclusion was round and eosinophilic, and positive for glial fibrillary acidic protein, vimentin, αB-crystallin, S-100 protein and microtubule associated protein 1B, immunohistochemically. An electron microscopic examination revealed an accumulation of intermediate filaments, ribosome and rough endoplasmic reticulum in the inclusion. The characteristic of this inclusion is different from that of other reported inclusions. The inclusion showed positive immunoreaction against CuZn superoxide dismutase, catalase, advanced glycation endproduct and 4-hydroxy-2-nonenal antibodies, which suggest that oxidative stress is involved in the genesis of the inclusion.