Contributed by Sarah E. Martin, Steven D. Allen, Phillip Faught, Dean A. Hawley, Jose M. Bonnin, and Eyas M. Hattab
Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
A previously healthy 2-year-old boy presented with one to two days of anuria and bloody diarrhea. He was admitted to the local children's hospital with a diagnosis of hemolytic uremic syndrome (HUS), presumably secondary to E. coli O157 but never confirmed. Laboratory studies revealed hemolysis, renal failure and thrombocytopenia. Eleven hours after admission, his blood oxygen saturations worsened and he was intubated. He was then noted to have fixed and dilated pupils. A head CT was performed, which revealed left frontal subcortical white matter vasogenic edema with left frontal gyral hyperdensity, as well as scattered pockets of pneumocephalus (Figure 1). Pneumocephalus without evidence of a calvarial fracture raised concern for an infectious process. Left-to-right midline shift with effacement of the cisterns and left uncal herniation were also observed. Neurosurgical consultation advised that no intervention was possible. The patient became bradycardic and required resuscitation, which unfortunately was not successful. He expired 14 hours after being admitted to the hospital. Ante-mortem bacterial blood cultures were positive.
Gross pathologic examination of the brain revealed a large area of intraparenchymal hemorrhage with necrosis and cavitation over the left frontal and parietal lobes. There was extensive midline shift with the left hemisphere being significantly larger than the right. Sequential coronal sections of the cerebrum displayed a 6.5 x 6 x 5.5 cm area of dark brown discoloration with friable tissue and cavitation in the left frontal and parietal lobes, extending down the internal capsule to the midbrain (Figures 2 and 3). There was extensive vacuolization involving the cortex, white matter, basal ganglia, caudate and putamen, most severe in the right parietal lobe. Left uncal herniation is seen (Figure 4). Sequential transverse sections of the brainstem perpendicular to its long axis displayed an area of hemorrhage with cystic spaces and discoloration in the left midbrain, continuing into the left pons (Figure 5). Microscopic examination of the cortex, white matter, deep grey matter, hippocampi, cerebellum and brainstem revealed multiple holes of varying sizes (Figure 6), as well as diffuse colonization with rod-shaped bacteria, but without the expected tissue response (Figures 7, 8 and 9).
General autopsy revealed a similar diffuse bacterial colonization of the lungs, kidneys, liver, and bowel (Figure 10), without an inflammatory response. The kidneys also showed stigmata of HUS, including numerous occlusive thrombi within the glomerular capillaries (Figure 11). There was also necrotizing colitis (Figure 10) and pneumatosis of the abdominal viscera including the colon, spleen, and retroperitoneal tissues.