Neuropathology of propionic acidemia: a report of two patients with basal ganglia lesions.

Propionic acidemia is a rare genetic disorder of amino acid metabolism caused by deficient activity of propionyl coenzyme A carboxylase. Neuropathologic changes previously reported in infants have been white-matter vacuolization or spongiosis. In children who survive beyond infancy, abnormalities have been found primarily in the basal ganglia. We report neuropathologic findings in two patients with propionic acidemia diagnosed in infancy who survived 35 months and 9 years, respectively. Examination of the brain of the 35-month-old boy showed vascular and parenchymal mineralization, focal pallor and spongy change, and foci of acute neuronal injury. These changes were similar to those previously described. The 9-year-old girl was in good metabolic control when she died, and presented a neuropathologic picture not previously described. She was found at autopsy to have acute hemorrhagic lesions in the caudate, putamen, and globus pallidus bilaterally and in the left ventral thalamus. There was focal neuronal loss, but no acute hypoxic/ischemic neuronal injury. Vascular proliferation and swollen endothelial cells were seen in the basal ganglia, thalamus, and substantia nigra, but not in other regions of the brain. Electron microscopy showed swelling of endothelial cells with viable adjacent brain parenchyma. The endothelial changes suggest a breakdown of the blood-brain barrier.