Clinicopathologic features and molecular analysis of enterovirus 71 infection: report of an autopsy case from the epidemic of hand, foot and mouth disease in China

A 15-month boy with fatal hand, foot, and mouth disease (HFMD) exhibited atypical symptoms and progressed rapidly to death. An autopsy was performed the next day and tissue sections were stained for histopathological examination. His intestinal samples were tested for enterovirus 71 (EV71), and the whole-genome sequence of EV71 was analyzed. An autopsy revealed that the central nervous system, lungs, and gut displayed severe meningitis and brainstem encephalitis, remarkable pulmonary congestion, edema, moderate inflammatory infiltration, and hemorrhage as well as intestinal mucosal congestion, epithelial necrosis, thinning intestinal wall, and submucosal lymphoid follicular hyperplasia. The heart showed myocardial interstitial congestion, myocardial edema, and some inflammatory infiltrates. There were no significant alterations in the architecture of other organs. EV71 antigen and apoptotic cells were detected in brain, lung and intestine by immunohistochemical staining and TUNEL (TdT-mediated dUTP nick-end labeling) respectively. Intestinal contents and intestinal autopsy samples of this case were positive for EV71, and the EV71 strain was classified as subgenogroup C4. In China, the severe forms of HFMD were mostly caused by EV71 subgenogroup C4 infection. Severe intestinal damages may relate to EV71 subgenogroup C4 infection. Thus, children with severe EV71 HFMD may have serious pathological changes in their central nervous system, lungs, and gut. Physicians should pay special attention to infants with atypical symptoms, particularly in EV71 epidemic areas for early diagnosis and treatment.