Pathological study on severe acute respiratory syndrome

OBJECTIVE

To study the pathological characteristics of severe acute respiratory syndrome (SARS) and its relationship to clinical manifestation.

METHODS

Tissue specimens from 3 autopsies of probable SARS cases were studied by microscope, and the clinical data was reviewed.

RESULTS

The typical pathological changes of lungs were diffuse hemorrhaging on the surface. A combination of serous, fibrinous and hemorrhagic inflammation was seen in most of the pulmonary alveoli with the engorgement of capillaries and detection of micro-thrombosis in some of these capillaries. Pulmonary alveoli thickened with interstitial mononuclear inflammatory infiltrates, suffered diffuse alveolar damage, experienced desquamation of pneumocytes and had hyaline-membrane formation, fibrinoid materials, and erythrocytes in alveolar spaces. There were thromboembolisms in some bronchial arteries. Furthermore, hemorrhagic necrosis was also evident in lymph nodes and spleen with the attenuation of lymphocytes. Other atypical pathological changes, such as hydropic degeneration, fatty degeneration, interstitial cell proliferation and lesions having existed before hospitalization were observed in the liver, heart, kidney and pancreas.

CONCLUSION

Severe damage to the pulmonary and immunological systems is responsible for the clinical features of SARS and may lead to the death of patients.

The clinical pathology of severe acute respiratory syndrome (SARS): a report from China

In order to investigate the clinical pathology of severe acute respiratory syndrome (SARS), the autopsies of three patients who died from SARS in Nan Fang Hospital Guangdong, China were studied retrospectively. Routine haematoxylin and eosin (H&E) staining was used to study all of the tissues from the three cases. The lung tissue specimens were studied further with Macchiavello staining, viral inclusion body staining, reticulin staining, PAS staining, immunohistochemistry, ultrathin sectioning and staining, light microscopy, and transmission electron microscopy. The first symptom was hyperpyrexia in all three cases, followed by progressive dyspnoea and lung field shadowing. The pulmonary lesions included bilateral extensive consolidation, localized haemorrhage and necrosis, desquamative pulmonary alveolitis and bronchitis, proliferation and desquamation of alveolar epithelial cells, exudation of protein and monocytes, lymphocytes and plasma cells in alveoli, hyaline membrane formation, and viral inclusion bodies in alveolar epithelial cells. There was also massive necrosis of splenic lymphoid tissue and localized necrosis in lymph nodes. Systemic vasculitis included oedema, localized fibrinoid necrosis, and infiltration of monocytes, lymphocytes, and plasma cells into vessel walls in the heart, lung, liver, kidney, adrenal gland, and the stroma of striated muscles. Thrombosis was present in small veins. Systemic toxic changes included degeneration and necrosis of the parenchyma cells in the lung, liver, kidney, heart, and adrenal gland. Electron microscopy demonstrated clusters of viral particles, consistent with coronavirus, in lung tissue. SARS is a systemic disease that injures many organs. The lungs, immune organs, and systemic small vessels are the main targets of virus attack, so that extensive consolidation of the lung, diffuse alveolar damage with hyaline membrane formation, respiratory distress, and decreased immune function are the main causes of death.

[A clinicopathological study on 3 cases of severe acute respiratory syndrome]

OBJECTIVE

To study the pathological characteristics of severe acute respiratory syndrome (SARS) and its relationship to clinical manifestation.

METHODS

Tissue specimens from 3 autopsy cases of diagnosed SARS were studied under microscopy and the clinical data were reviewed.

RESULTS

The typical pathological changes of lungs were diffuse hemorrhage on surface. A mixture features of serous, fibrinous and hemorrhagic inflammation were seen in most pulmonary alveoli with engorgement of capillary and there were microthrombosis in some capillary. Pulmonary alveoli became thick with interstitial mononuclear inflammatory infiltration, diffused alveoli damage, desquamation of pneumocytes and hyaline-membrane formation. Fibrinoid materials and erythrocytes could be found in alveolar spaces. There were thrombo-embolisms in some bronchial artery. Meanwhile, haemorrhagic necrosis was showed in lymph nodes and spleen with attenuation of lymphocytes. Other atypical pathological changes, such as hydropic degeneration, fatty degeneration, interstitial cell proliferation and some lesions observed in liver, heart, kidney, pancreas may have existed before the hospitalization.

CONCLUSION

Severe damages of pulmonary and immunological system damage are responsible for clinical features of SARS and may lead to death of patients.

Severe acute respiratory syndrome and its lesions in digestive system

Severe acute respiratory syndrome (SARS) is an infectious atypical pneumonia that has recently been recognized in the patients in 32 countries and regions. This brief review summarizes some of the initial etiologic findings, pathological description, and its lesions of digestive system caused by SARS virus. It is an attempt to draw gastroenterologists and hepatologists' attention to this fatal illness, especially when it manifests itself initially as digestive symptoms.

Early X-ray and CT appearances of severe acute respiratory syndrome: an analysis of 28 cases

OBJECTIVE

To study the early X-ray and CT findings of patients with severe acute respiratory syndrome (SARS).

METHODS

Chest radiography and CT were performed in 28 patients with SARS within one to three days after onset of the disease. CT examinations included conventional spiral CT and high-resolution CT (HRCT). The radiographic and CT findings of these patients were analyzed retrospectively.

RESULTS

Abnormal CT findings were noted in all the patients, but abnormal chest radiographic findings in 17 cases (60.7%, 17/28). CT showed single small focal patchy opacities in 23 patients (82.1%, 23/28), including oval ground-glass opacities in 20 patients, lobular distribution ground-glass opacities in 2 and small patchy consolidation in one. Multi-focal ground-glass opacities were found in 2 patients and extensive opacities in three. In the 28 patients, a total of 31 lesions were found in the upper (7, 22.6%), middle (3, 9.7%), and lower lobes (21, 67.7%). The diameter of the lesions ranged from 20 to 35 mm.

CONCLUSION

The dominant feature of early SARS patients is focal patchy opacity in the lung, and oval small ground-glass opacities are the common morphological findings on CT.

[Severe acute respiratory syndrome]

OBJECTIVE

Severe acute respiratory syndrome(SARS), caused by SARS- associated coronavirus(SCV), is the first severe infectious disease in this century. SARS is pathologically characterized by interstitial exudative inflammation of lung with the formation of hyaline membrane in acute phase. Haemorrhagic inflammation exists in extrapulmonary organs. Clinical diagnosis is a dynamic process and includes the suspected case, probable case and definite case. Diagnostic standard of SARS will be revised with further understanding of the disease. Chinese term of SARS has been recommended in the paper.

[Analysis of chest X-ray manifestations in 118 patients with severe acute respiratory syndrome]

OBJECTIVE

To investigate the chest X-ray features and kinetic changes in patients with severe acute respiratory syndrome (SARS).

METHODS

The appearing time, site, range and imaging features of pulmonary lesions in chest radiograms were observed in 118 patients with clinically confirmed SARS treated in our hospital. Meanwhile, their relation to clinical manifestations was also evaluated.

RESULTS

Abnormal image appeared in the radiogram in 99.2% of the patients, and it was found in 79.7% of the patients within 4 days after onset of SARS. Lesions in both lungs and multi-lobe pathological changes were noted in 52.2% of the patients. In seven non-survivors, the lesions were included multi-lung lobes, revealing earlier appearance and faster progression compared with the others.

CONCLUSION

The more serious clinical symptoms and poor prognosis are found in patients with earlier appearance, larger scope and faster progression of SARS lesions in the chest radiogram.

[Evaluation of glucocorticoid in treatment for patients with acute respiratory distress syndrome]

OBJECTIVE

To value of glucocorticoid (GC) in treatment for patients with acute respiratory distress syndrome (ARDS) was evaluated.

METHODS

The clinical data from all patients with ARDS in medical ICU (MICU) during May 2000 to Aug. 2002 were collected. They were divided into two groups, GC and non-GC groups, in order to compare their age, sex, acute physiology and chronic health evaluation II (APACHE II) score, PaO2/FiO2, Qs/Qt, level of positive end-expiratory pressure(PEEP), mortality and dead reason of death, depending on whether GC was given or not. In cases with administration of GC, the dosage, as well as duration of treatment was analyzed in terms of the overcome.

RESULTS

There were 77 cases totally, among them 60 cases were of GC group and 17 of non -GC. Their age, sex, APACHE II score, PaO2/FiO2, Qs/Qt, use of artificial ventilation and its duration, level of PEEP, and the extent of relief from hypoxemia showed no significant differences between two groups (P>0.05). Even the mortality for patients who were treated with GC was higher than those without (71.7% vs. 52.9%), though there was no statistically significant difference (P>0.05). The percentage of patients died primarily of ARDS was low in both groups (7.0% and 11.1%). The age, APACHE II score and underlying diseases for non-survivors were older and higher than survivors (P<0.001 or P<0.005) and their duration of staying in ICU was shorter than the latter (P<0.05). The mortality of patients who were given GC before or during 24 hours of the establishment of the diagnosis of ARDS (66.7% and 68.2%) was lower than those who were given GC 24 hours after the diagnosis of ARDS (90.0%).

CONCLUSION

GC could be one of effective treatments for ARDS, and it should be given without hesitation when refractory hypoxemia and shock were found.

[Lung pathology of severe acute respiratory syndrome]

OBJECTIVE

To study the morphological features of the lungs obtained from autopsies of severe acute respiratory syndrome (SARS) patients.

METHODS

Bilateral lungs from 7 patients died from SARS were carefully studied grossly and microscopically. All tissues from these cases were routinely processed and carefully studied.

RESULTS

All lungs from these cases were extremely expanded and became solid. Microscopically, the edema and fibrin exudates in the alveoli was the most common findings, especially in the early phase of the disease. The hyaline membrane was almost always present in the lungs of these cases. The organization of intra-alveolar fibrin exudates along with the interstitial fibrosis led to obliteration of alveoli and consolidation of lungs. The desquamation and hyperplasia of alveolar lining cells was also apparent. Foci of haemorrhage and lobular pneumonia, even diffuse fungal infection were frequently seen in these specimens. Micro-thrombus were easily found in these lungs.

CONCLUSIONS

The lung of SARS from autopsy is characterized by edema, intra-alveolar fibrin exudates, hyaline membrane formation, organization of intra-alveolar exudates and fibrosis, which lead to the obliteration of alveoli and consolidation of lungs.

[Pathological and ultramicrostructural changes of tissues in a patient with severe acute respiratory syndrome]

OBJECTIVE

To study the morphological, ultramicrostructural and pathological changes of tissues from a patient with severe acute respiratory syndrome (SARS).

METHODS

One autopsy case of diagnosed SARS was investigated. Lung puncture was performed immediately after the patient died, and the autopsy was done after 12 h. The specimens from lymph nodes, spleen, small intestine, colon and bone marrow were studied by immunohistochemical technique. The antibodies used included CD20, CD45RO (UCHL-1), CD4, CD8, CD68 and CD34.

RESULTS

The principal lesions of the SARS case consisted of acute lobular intrastitial pneumonia, hyaloid membranes of pulmonic alveoli and hyperplasia and shedding of alveolar epithelium of. Virus-like inclusions occasionally contained cytoplasm of the alveolar epithelium, which were positive by histochemical staining. The adjacent blood-vessels were changed by hyperplasia and enlargement. The structures of lymph nodes and spleen were damaged with lymph follicles depletion and splenic nodules atrophy. The specific changes included reduction of lymphocytes and hyperplasia of histiocytes, depletion of the follicles of small intestine and colon wall, decreased hyperplasia of the bone marrow and increased number of the megakaryocyte. Meanwhile, in the immunohistochemical study, CD(20)(+) B cells were fully expressed in lymph nodes and spleen, and the CD45RO (UCHL-1)(+) T cells were scatteredly expressed. The number of CD4(+) help T cell was markedly decreased, while the number of CD8+ poisonal T cells increased, and the ratio of the former and latter was no more than 0.5. Under the electronic microscopy observation, virus-like particles with 80 - 160 nm diameter and halo or garland envelope were found in mononuclear macrophage and cytoplasm of alveolar epithelium.

CONCLUSION

The specific lesions of SARS consist of lobular intrastitial pneumonia with the formation of hyaline membranes of lung, haemorrhage, necrosis, inflammation of blood vessels and the damages of extralung lymphohemopioetic system. The damages were very similar to the pathological features of tissues infected by human immunodeficiency virus, in which numbers of T cells decreased and CD(4)(+) T cell/CD(8)(+) T cell ratio was no more than 0.5. According to the virus-like particles found in lung of the SARS case, it is considered that these virus-like particles may be a new kind of coronavirus which caused the "atypical pneumonia".

[Study on etiology and pathology of severe acute respiratory syndrome]

OBJECTIVE

To investigate the clinicopathologic characteristics of severe acute respiratory syndrome (SARS).

METHODS

Three autopsy cases were studied retrospectively. Routine HE stain was used to study all the cases. Part of the lung tissue specimens were studied further with Macchiavello's stain, viral inclusion body stain, reticulin and PAS stains, immunohistochemistry, thin sections with staining, light microscopy and transmission electronic microscope investigation.

RESULTS

The earliest symptom of all 3 cases was hyperpyrexia and followed by progressive dyspnea and appearance of lung field shadows in X rays findings. Pulmonary lesions included: bilateral and extensive consolidation, localized hemorrhage and necrosis, desquamative alveolitis and bronchitis, alveolar proliferation and desquamation, accumulation of protein exudates, mononuclear cells, lymphocytes, and plasma cells as well as hyaline membrane formation in alveoli and viral inclusion bodies were seen in the alveolus epithelial cells. The exudated organization tended to become glomeruloid organizing pneumonitis in a few avaoli. Lesions of the immune organs included: large patchy necrosis in the spleens and localized necrosis in the lymph nodes were seen. Bone marrow became restrained. There were lesions of systemic small vasculitis including edema of the perivascular tissue and vascular wall of the small veins with localized fibrinoid necrosis distributing in the heart, lungs, kidneys, adrenal glands and the striated muscles accompanying with mononuclear cells and lymphocytes infiltration. Thrombosis was seen in part of the small veins. In addition, there were also the systemic poisonous changes including: degeneration and necrosis of the parenchyma cells in lungs, liver, kidneys, heart and adrenals. Electronic microscopy demonstrated clusters of virus particles seen in the lung tissue.

CONCLUSION

SARS is a systemic disease. Lungs, immune system and systemic small vessels are the main target organs attacked by the virus. Extensive consolidation of lungs, formation of hyaline membrane to a large extent, respiratory distress and decrease of immune function are the main causes of death.

Lung pathology of fatal severe acute respiratory syndrome

BACKGROUND

Severe acute respiratory syndrome (SARS) is a novel infectious disease with global impact. A virus from the family Coronaviridae has been identified as the cause, but the pathogenesis is still unclear.

METHODS

Post-mortem tissue samples from six patients who died from SARS in February and March, 2003, and an open lung biopsy from one of these patients were studied by histology and virology. Only one full autopsy was done. Evidence of infection with the SARS-associated coronavirus (SARS-CoV) and human metapneumovirus was sought by reverse-transcriptase PCR and serology. Pathological samples were examined by light and electron microscopy and immunohistochemistry.

FINDINGS

All six patients had serological evidence of recent infection with SARS-CoV. Diffuse alveolar damage was common but not universal. Morphological changes identified were bronchial epithelial denudation, loss of cilia, and squamous metaplasia. Secondary bacterial pneumonia was present in one case. A giant-cell infiltrate was seen in four patients, with a pronounced increase in macrophages in the alveoli and the interstitium of the lung. Haemophagocytosis was present in two patients. The alveolar pneumocytes also showed cytomegaly with granular amphophilic cytoplasm. The patient for whom full autopsy was done had atrophy of the white pulp of the spleen. Electron microscopy revealed viral particles in the cytoplasm of epithelial cells corresponding to coronavirus.

INTERPRETATION

SARS is associated with epithelial-cell proliferation and an increase in macrophages in the lung. The presence of haemophagocytosis supports the contention that cytokine dysregulation may account, at least partly, for the severity of the clinical disease. The case definition of SARS should acknowledge the range of lung pathology associated with this disease.

A novel coronavirus associated with severe acute respiratory syndrome

BACKGROUND

A worldwide outbreak of severe acute respiratory syndrome (SARS) has been associated with exposures originating from a single ill health care worker from Guangdong Province, China. We conducted studies to identify the etiologic agent of this outbreak.

METHODS

We received clinical specimens from patients in seven countries and tested them, using virus-isolation techniques, electron-microscopical and histologic studies, and molecular and serologic assays, in an attempt to identify a wide range of potential pathogens.

RESULTS

None of the previously described respiratory pathogens were consistently identified. However, a novel coronavirus was isolated from patients who met the case definition of SARS. Cytopathological features were noted in Vero E6 cells inoculated with a throat-swab specimen. Electron-microscopical examination revealed ultrastructural features characteristic of coronaviruses. Immunohistochemical and immunofluorescence staining revealed reactivity with group I coronavirus polyclonal antibodies. Consensus coronavirus primers designed to amplify a fragment of the polymerase gene by reverse transcription-polymerase chain reaction (RT-PCR) were used to obtain a sequence that clearly identified the isolate as a unique coronavirus only distantly related to previously sequenced coronaviruses. With specific diagnostic RT-PCR primers we identified several identical nucleotide sequences in 12 patients from several locations, a finding consistent with a point-source outbreak. Indirect fluorescence antibody tests and enzyme-linked immunosorbent assays made with the new isolate have been used to demonstrate a virus-specific serologic response. This virus may never before have circulated in the U.S. population.

CONCLUSIONS

A novel coronavirus is associated with this outbreak, and the evidence indicates that this virus has an etiologic role in SARS. Because of the death of Dr. Carlo Urbani, we propose that our first isolate be named the Urbani strain of SARS-associated coronavirus.

[Chlamydia-like and coronavirus-like agents found in dead cases of atypical pneumonia by electron microscopy]

OBJECTIVE

To explore the causative agents of the atypical pneumonia (also SARS) occurred recently in some regions of our country.

METHOD

Organ samples of 7 dead cases of SARS were collected from Guangdong, Shanxi, Sichuan Provinces and Beijing for electron microscopic examination. 293 cell line was inoculated with the materials derived from the lungs to isolate causative agent(s). The agents in the organs and cell cultures were revealed by immunoassay.

RESULTS

Both Chlamydia-like and coronavirus-like particles were found in EM. Inclusion bodies containing elementary bodies, reticulate antibodies and intermediate bodies of Chlamydia-like agent were visualized in multiple organs from the 7 dead cases, including lungs (7 cases), spleens (2 cases), livers (2 cases), kidneys (3 cases) and lymph nodes (1 cases), by ultrathin section electron microscopy (EM). In some few sections, coronavirus-like particles were concurrently seen. A coronavirus RNA- polymerase segment (440 bp) was amplified from the lung tissues of two cases of the SARS. After inoculated with materials from the lung samples, the similar Chlamydia-like particles were also found in the inoculated 293 cells. Since the Chlamydia-like agents visualized in both organs and cell cultures could not react with the genus specific antibodies against Chlamydia and monoclonal antibodies against C. pneumoniae and C. psittaci, the results might well be suggestive of a novel Chlamydia-like agent.

CONCLUSION

Since the novel Chlamydia-like agent was found co-existing with a coronavirus-like agent in the dead cases of SARS, it looks most likely that both the agents play some roles in the disease. At the present time, however, one can hardly determining how did these agents interact each other synergetically, or one follows another, need further study.