Tonsillar crypt epithelium is an important extra-central nervous system site for viral replication in EV71 encephalomyelitis.

Enterovirus 71 (EV71; family Picornaviridae, species human Enterovirus A) usually causes hand, foot, and mouth disease, which may rarely be complicated by fatal encephalomyelitis. We investigated extra-central nervous system (extra-CNS) tissues capable of supporting EV71 infection and replication, and have correlated tissue infection with expression of putative viral entry receptors, scavenger receptor B2 (SCARB2), and P-selectin glycoprotein ligand-1 (PSGL-1). Formalin-fixed, paraffin-embedded CNS and extra-CNS tissues from seven autopsy cases were examined by IHC and in situ hybridization to evaluate viral antigens and RNA. Viral receptors were identified with IHC. In all seven cases, the CNS showed stereotypical distribution of inflammation and neuronal localization of viral antigens and RNA, confirming the clinical diagnosis of EV71 encephalomyelitis. In six cases in which tonsillar tissues were available, viral antigens and/or RNA were localized to squamous epithelium lining the tonsillar crypts. Tissues from the gastrointestinal tract, pancreas, mesenteric nodes, spleen, and skin were all negative for viral antigens/RNA. Our novel findings strongly suggest that tonsillar crypt squamous epithelium supports active viral replication and represents an important source of viral shedding that facilitates person-to-person transmission by both the fecal-oral or oral-oral routes. It may also be a portal for viral entry. A correlation between viral infection and SCARB2 expression appears to be more significant than for PSGL-1 expression.

[A histopathological study on Influenza A H1N1 infection in humans].

OBJECTIVE: To find histopathological changes on major organs of Influenza A H1N1-infected patients and its relationship to clinical symptoms. METHODS: The autopsies were performed following conventional protocols and strict safety procedures. Tissue samples from all major organs of three cases were collected and fixed in 4% formalin. The histopathological changes on these samples were observed under a light microscope. RESULTS: The lungs of some damaged areas of three cases showed diffuse alveolar damage (DAD) with hyaline membranes formation and intra-alveolar edema and/or fibrin. Most areas of the lungs in the three cases showed necrotizing bronchiolitis, hemorrhage, secondary infection, thrombosis and focal alveolar necrosis. The lungs exhibited proliferation of pneumocytes and fibrosis of the interstitium in one case. In one case, the brain showed focal hemorrhage and focal liquefactive necrosis. In one case, the heart showed edema. CONCLUSION: The respiratory tract is the major target of influenza A H1N1 virus. The changes of DAD with secondary infection in the lung resulted in hypoxia, leading to multiple organ failure and death.

[High-risk factors and clinical pathological analysis in 21 cases of fatal pulmonary embolism].

OBJECTIVE: To explore the clinical and pathological characteristics of fatal pulmonary thromboembolism, especially the contribution of acquired and genetic risk factors of fatal pulmonary thromboembolism, so as to provide some useful information for its clinical prevention and treatment. METHODS: The medical dispute autopsy cases performed at the Department of Pathology, School of Basic Medical Sciences, Peking University from January 1, 2002 to September 30, 2008 were retrospectively reviewed. FV ( factor V ) Leiden mutation and FII ( factor II) G20210A mutation were analyzed by using methods of PCR and restriction fragment length polymorphism (RFLP) in fatal pulmonary embolism cases and random selected control cases of adult autopsy. RESULTS: There were 21 patients who died from fatal pulmonary thromboembolism, accounting for 12.96% (21/162) of adult autopsy cases. In these cases, there was at least one of the known risk factors in each case and more than two risk factors could be found in most cases. The acquired risk factors, such as surgery, trauma and fractures, cancer, pregnancy and puerperium, the elderly, hypertension, diabetes, infections, could be found in these patients. FV Leiden mutation and FII G20210A mutation were not detected in any of the 21 cases of fatal pulmonary thromboembolism cases and six control cases. Of all the 21 cases, quantitative D-dimer measurement was performed only in six patients and D-dime level in these six samples was all significantly increased. According to the records, there was only 1 patient treated by preventive anticoagulants in the 21 patients. CONCLUSION: Fatal pulmonary thromboembolism is an important reason for medical dispute. Fractures and trauma, surgery and other acquired factors are the main reasons for fatal pulmonary embolism in Chinese. Genetic factors (FV Leiden and FII G20210A mutations) are not the reason for Chinese to suffer from fatal pulmonary thromboembolism. Assessment of risk factors (especially traumatic fractures and surgical intervention) of pulmonary thromboembolism may play an important role in taking appropriate preventive procedures, early diagnosis and reasonable treatment to reduce its mortality.

[Molecular confirmation of enterovirus type 71 infection: a post-mortem study of two cases].

OBJECTIVE: To investigate the diagnostic application of molecular detection of enterovirus type 71 (EV71) infection using post-mortem paraffin-embedded tissue. METHODS: Two autopsy cases of EV71 infection were studied by histopathological and immunohistochemical methods. Reverse transcription polymerase chain reaction (RT-PCR) was performed to detect the viral RNA in paraffin-embedded tissue samples. RESULTS: Characteristic features of acute encephalitis were seen in the brain, with most prominent lesions found in the brain stem in both cases. Inflammatory cells were largely CD68-positive microglia with a few CD15-positive neutrophils in the areas of neuronal necrosis. The 5'-untranslated region of EV71 was detected in the medulla by RT-PCR using paraffin-embedded tissues of both cases. Sequencing analysis of the RT-PCR products showed 100% homology to the EV71 strain, recently submitted to the GenBank database from Fuyang, Anhui province. CONCLUSIONS: Molecular detection of EV71 can be performed on formalin-fixed, paraffin-embedded tissue samples from fatally infected patients. Timely and accurate diagnosis of the infection by such molecular approach is crucial for the proper clinical and public health intervention.

[Pathology of enterovirus 71 infection: an autopsy study of 5 cases].

OBJECTIVE: To study the clinicopathologic features of fatal enterovirus 71 (EV71) infection. METHODS: Autopsy was performed in 5 neonates died of EV71 infection. Tissue samples from major organs were collected, formalin-fixed and examined under light microscopy. Immunohistochemical study was carried out in selected examples. RESULTS: Four of the 5 cases showed predominant changes in central nervous system, with encephalitis and encephalomyelitis identified mainly in brainstem and upper cervical spinal cord. Histologic findings included neuronal degeneration and necrosis, neuronophagia, perivascular cuffing and diffuse or nodular hyperplasia of macrophages/microglia. Cerebral edema, brain herniation and aseptic meningitis were also noted. The lungs showed mainly pulmonary congestion, neurogenic pulmonary edema and focal hemorrhage. There were minimal changes in the intestinal epithelium. The intestinal lymphoid tissue however was hyperplastic and associated with apoptosis of follicular center cells. The remaining case had cerebral edema and mild meningitis. The lung alveolar septa were thickened with lymphocytic infiltrates. Some alveolar cells were hyperplastic and associated with diffuse hyaline membrane formation. No specific abnormalities were identified in gastrointestinal tract. In all the 5 cases studied, there was enlargement of lung hilar and mesenteric lymph nodes, coupled with apoptosis of follicular center cells. In general, no significant pathologic changes were demonstrated in heart, liver and kidneys. CONCLUSIONS: In fatal EV71 infection, the major pathologic changes lie in the central nervous system. The pulmonary lesions are mainly secondary in nature. The usual cause of death is cerebral edema complicated by brain herniation and pulmonary edema. It is also noteworthy that some cases show only lung damages, without classic neurologic changes.

Neuropathology in 2 cases of fatal enterovirus type 71 infection from a recent epidemic in the People's Republic of China: a histopathologic, immunohistochemical, and reverse transcription polymerase chain reaction study.

Between late March and June of 2008, an outbreak of hand, foot, and mouth disease caused by enterovirus 71 occurred in China. In this outbreak, more than 176,000 cases occurred, and at least 40 people died. However, there has been no description of the neuropathologic features of fatal enterovirus 71 infection cases during this outbreak. We report postmortem studies in 2 fatal cases of enterovirus 71 infection with examination of the central nervous system using histopathology, immunohistochemistry, and reverse transcription polymerase chain reaction. Characteristic features of acute encephalitis were found predominantly in the brain stem and spinal cord. Abundant numbers of inflammatory cells with unusual irregularly rod-shaped and lobulated nuclei, which mimicked neutrophil morphology, were found both in abscess-like clusters associated with necrosis, as well as in inflammatory infiltrates. Immunohistochemistry showed that most of these cells were CD68 positive and CD15 negative. Viral antigens were found in the cytoplasm of neurons, neuronal processes, and inflammatory cells, most often associated with glial nodules. The presence of enterovirus 71 was confirmed by reverse transcription polymerase chain reaction and sequencing. Results indicate that immunohistochemistry with CD68 and CD15 may offer some help in the differential diagnosis of brain stem encephalitis caused by enterovirus 71. Postmortem reverse transcription polymerase chain reaction from brain stem tissues, which have already undergone fixation and histologic processing, can be an important diagnostic tool, which may be of particular value in patients who may have been misdiagnosed clinically.