• Clinical and Experimental Pediatrics
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• v.63 no.7
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• pp.239-250
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• 2020

The novel coronavirus disease 2019 (COVID-19) is spreading globally. Although its etiologic agent is discovered as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), there are many unsolved issues in COVID-19 and other infectious diseases. The causes of different clinical phenotypes and incubation periods among individuals, species specificity, and cytokine storm with lymphopenia as well as the mechanism of damage to organ cells are unknown. It has been suggested that in viral pneumonia, virus itself is not a direct cause of acute lung injury; rather, aberrant immune reactions of the host to the insults from viral infection are responsible. According to its epidemiological and clinical characteristics, SARS-CoV-2 may be a virus with low virulence in nature that has adapted to the human species. Current immunological concepts have limited ability to explain such unsolved issues, and a presumed immunopathogenesis of COVID-19 is presented under the protein-homeostasis-system hypothesis. Every disease, including COVID-19, has etiological substances controlled by the host immune system according to size and biochemical properties. Patients with severe pneumonia caused by SARS-CoV-2 show more severe hypercytokinemia with corresponding lymphocytopenia than patients with mild pneumonia; thus, early immunomodulator treatment, including corticosteroids, has been considered. However, current guidelines recommend their use only for patients with advanced pneumonia or acute respiratory distress syndrome. Since the immunopathogenesis of pneumonia may be the same for all patients regardless of age or severity and the critical immune-mediated lung injury may begin in the early stage of the disease, early immunomodulator treatment, including corticosteroids and intravenous immunoglobulin, can help reduce morbidity and possibly mortality rates of older patients with underlying conditions.

• Clinical and Experimental Pediatrics
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• v.61 no.9
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• pp.291-300
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• 2018

Purpose: Understanding changes in pathogen and pneumonia prevalence among pediatric pneumonia patients is important for the prevention of infectious diseases. Methods: We retrospectively analyzed data of children younger than 18 years diagnosed with pneumonia at 117 Emergency Departments in Korea between 2007 and 2014. Results: Over the study period, 329,380 pediatric cases of pneumonia were identified. The most frequent age group was 1-3 years old (48.6%) and the next was less than 12 months of age (17.4%). Based on International Classification of Diseases, 10th revision diagnostic codes, confirmed cases of viral pneumonia comprised 8.4% of all cases, pneumonia due to Mycoplasma pneumoniae comprised 3.8% and confirmed cases of bacterial pneumonia 1.3%. The prevalence of confirmed bacterial pneumonia decreased from 3.07% in 2007 and 4.01% in 2008 to 0.65% in 2014. The yearly rate of pneumococcal pneumonia also decreased from 0.47% in 2007 to 0.08% in 2014. A periodic prevalence of M. pneumoniae pneumonia (MP) was identified. Conclusion: The increased number of patients with pneumonia, bacterial pneumonia, pleural effusion, and empyema in 2011 and 2013-2014 resulted from an MP epidemic. We provide evidence that the frequency of confirmed cases of bacterial pneumonia and pneumococcal pneumonia has declined from 2007 to 2014, which can simultaneously reflect the effectiveness of the pneumococcal conjugate vaccine.

• Journal of Yeungnam Medical Science
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• v.34 no.2
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• pp.182-190
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• 2017

Background: Respiratory viruses play a significant role in the etiology of acute respiratory infections and exacerbation of chronic respiratory illnesses. This study was conducted to identify the epidemiological and clinical characteristics of children with acute viral lower respiratory infections. Methods: This study investigated 1,168 children diagnosed with acute viral lower respiratory tract infections (RTIs) between January 2012 and December 2014. Specimens of respiratory viruses were collected using a nasopharyngeal swab and analyzed by reverse transcriptase polymerase chain reaction. We retrospectively reviewed the medical records and analyzed the clinical features of children hospitalized for acute lower respiratory infections. Results: Respiratory syncytial virus (RSV), the main cause of infection in children aged <5 years, was the most commonly detected pathogen in children with bronchiolitis and pneumonia, and resulted in high proportions of children requiring oxygen treatment and intensive care unit admission. Rhinovirus was preceded by RSV as the second most common cause of bronchiolitis and pneumonia, and was detected most frequently in the children aged ${\geq}6$ years. In addition, asthma was predominantly caused by rhinovirus in children aged ${\geq}6$ years, whereas croup was mostly caused by parainfluenza virus in those aged <5 years. Rhinovirus infection (p<0.001) and history of asthma (p=0.049) were identified as significant risk factors for readmission within a month. Conclusion: We identified the epidemiological and clinical characteristics of respiratory viruses in children with acute lower respiratory infections during the last 3 years. Our findings may provide useful clinical insight to comprehend the acute viral lower RTIs in children.

• Korean Journal of Radiology
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• v.21 no.5
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• pp.545-549
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• 2020

The 2019 novel coronavirus (2019-nCoV) outbreak in Wuhan, Hubei Province, China in 2019 led to large numbers of people being infected and developing atypical pneumonia (coronavirus disease 2019, COVID-19). Typical imaging manifestations of patients infected with 2019-nCoV has been reported, but we encountered an atypical radiological manifestation on baseline computed tomography (CT) images in three patients from Wuhan, China infected with the 2019-nCoV. Surprisingly, the only similar CT finding was a solitary sub-centimeter ground-glass nodule adjacent to bronchovascular bundles, which could be easily overlooked. In addition, the follow-up images in these patients showed how COVID-19 pneumonia evolved from these small nodules. The radiologic manifestation of the three cases will expand contemporary understanding of COVID-19.

• Korean Journal of Radiology
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• v.21 no.10
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• pp.1161-1164
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• 2020

The epidemic of 2019 novel coronavirus, later named as coronavirus disease (COVID-19), began in Wuhan, China in December 2019 and has spread rapidly worldwide. Early diagnosis is crucial for the management of the patients with COVID-19, but the gold standard diagnostic test for this infection, the reverse transcriptase polymerase chain reaction, has a low sensitivity and an increased turnaround time. In this scenario, chest computed tomography (CT) could play a key role for an early diagnosis of COVID-19 pneumonia. Here, we have reported a confirmed case of COVID-19 with an atypical CT presentation showing a "double halo sign," which we believe represents the pathological spectrum of this viral pneumonia.

• Clinical and Experimental Pediatrics
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• v.59 no.3
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• pp.132-138
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• 2016

Purpose: Acute respiratory infection, particularly pneumonia, is the most common cause of hospitalization and death among children in developing nations. This study aimed to investigate the characteristics of children and adolescents with pneumonia who visited Emergency Department (ED) in South Korea in 2012. Methods: We analyzed National Emergency Department Information System (NEDIS) records from 146 EDs in South Korea for all pediatric patients aged ${\leq}18years$ who were diagnosed with pneumonia between January and December 2012. Results: Among 38,415 subjects, the male-to-female ratio was 1:0.8. Patients aged <12 months comprised 18.0% of the study population; those aged 1 to 3 years, 54.4%; those aged 4 to 6 years, 16.8%; those aged 7 to 12 years, 7.4%; and those aged 13 to 18 years, 3.4%. Presentation rates were highest in April, followed by January, March, and May. The hospital admission rate was 43.5%, of which 2.6% were in intensive care units. The mortality rate was 0.02%. Based on the International Classification of Diseases, 10th Revision, diagnostic codes, the types of pneumonia according to cause were viral pneumonia (29.0%), bacterial pneumonia (5.3%), Mycoplasmal pneumonia (4.5%), aspiration pneumonia (1.3%), and pneumonia of unknown origin (59.3%). Conclusion: Despite the limited data due to the ED data from the NEDIS lacking laboratory results and treatment information, this study reflects well the outbreak patterns among children and adolescents with pneumonia. Our results provide a basis for future studies regarding ED treatment for children and adolescents with pneumonia.

• Pediatric Infection and Vaccine
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• v.4 no.1
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• pp.167-173
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• 1997

Acute infectious mononucleosis, caused by Epstein-Barr virus(EBV), is a self limited lymphoproliferative illness that is common in adolescents and young adults. It shows many complications in multiple organ systems, but the hepatobiliary and the respiratory complication is uncommon. We report a case with thickened gallbladder wall and pneumonia as complications of acute infectious mononucleosis in a child. Also the related literature were reviewed. A 4 year old boy presented with a history of high fever, cough, and abdominal distension for 20days. Physical Examination revealed audible crackles in whole lung field and gross hepatomegaly. Chest X-ray showed pneumonia and liver function tests were abnormal. Ultrasonography and computed tomography revealed a thickened gallbladder wall and hepatosplenomegaly. The diagnosis of primary Epstein-Barr viral infection was eventually made by specific serologic tests. The patients's fever subsided 6 weeks later and pneumonia was recovered around this time. Liver function tests returned near normal 2 months later and ultrasonography of gallbladder was normal at this time.

• Tuberculosis and Respiratory Diseases
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• v.80 no.4
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• pp.392-400
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• 2017

Background: Most patients with influenza recover spontaneously or following treatment with an anti-viral agent, but some patients experience pneumonia requiring hospitalization. We conducted a retrospective review to determine the incidence and risk factors of pneumonia in hospitalized patients with influenza A or B. Methods: A total of 213 patients aged 18 years or older and hospitalized with influenza between January 2012 and January 2015 were included in this study. A reverse-transcriptase polymerase chain reaction assay was used to detect the influenza A or B virus in the patients' sputum samples. We collected demographic and laboratory data, combined coexisting diseases, and radiologic findings. Results: The incidence of pneumonia was higher in patients in the influenza A group compared to those in the influenza B group (68.6% vs. 56.9%), but this difference was not statistically significant. The presence of underlying respiratory disease was significantly associated with pneumonia in the influenza A group (adjusted odds ratio [OR], 3.975; 95% confidence interval [CI], 1.312-12.043; p=0.015). In the influenza B group, the white blood cell count (adjusted OR, 1.413; 95% CI, 1.053-1.896; p=0.021), platelet count (adjusted OR, 0.988; 95% CI, 0.978-0.999; p=0.027), and existence of an underlying medical disease (adjusted OR, 15.858; 95% CI, 1.757-143.088; p=0.014) were all significantly associated with pneumonia in multivariate analyses. Conclusion: The incidence of pneumonia was 65.7% in hospitalized patients with influenza A or B. The risk factors of pneumonia differed in hospitalized patients with influenza A or B.

• Korean Journal of Radiology
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• v.21 no.5
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• pp.537-540
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• 2020

Recently, some global cases of 2019 novel coronavirus (COVID-19) pneumonia have been caused by second- or third-generation transmission of the viral infection, resulting in no traceable epidemiological history. Owing to the complications of COVID-19 pneumonia, the first symptom and imaging features of patients can be very atypical and early diagnosis of COVID-19 infections remains a challenge. It would aid radiologists and clinicians to be aware of the early atypical symptom and imaging features of the disease and contribute to the prevention of infected patients being missed.

• Tuberculosis and Respiratory Diseases
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• v.81 no.4
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• pp.349-349
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• 2018