Histologic features and predicting prognosis in ulcerative colitis patients with mild endoscopic activity

Background/Aims@#We aimed to evaluate the histologic features predictive of prognosis and correlate them with endoscopic findings in patients with ulcerative colitis (UC) having complete or partial mucosal healing (MH). @*Methods@#We prospectively collected and reviewed data from patients with UC who underwent colonoscopy or sigmoidoscopy with biopsy. Complete and partial MH were defined as Mayo endoscopic subscores (MESs) of 0 and 1, respectively. Histologic variables, including the Nancy index (NI), predicting disease progression (defined as the need for medication upgrade or hospitalization/surgery), were evaluated and correlated with endoscopic findings. @*Results@#Overall, 441 biopsy specimens were collected from 194 patients. The average follow-up duration was 14.7 ± 7.4 months. There were 49 (25.3%) and 68 (35.1%) patients with MESs of 0 and 1, respectively. Disease progression occurred only in patients with an MES of 1. NI ≥ 3 was significantly correlated with disease progression during follow-up. Mucosal friability on endoscopy was significantly correlated with NI ≥ 3 (61.1% in NI < 3 vs. 88.0% in NI ≥ 3; p = 0.013). @*Conclusions@#Histological activity can help predict the prognosis of patients with UC with mild endoscopic activity. Mucosal friability observed on endoscopy may reflect a more severe histological status, which can be a risk factor for disease progression.

The Impact of Slow Infusion Intermittent Feeding on Gavage Feeding-Associated Cardiorespiratory Deterioration in Neonatal Intensive Care Unit Infants

Purpose@#Infants in the neonatal intensive care unit (NICU) often show cardiorespiratory deterioration during gavage feeding. We aimed to determine whether slow infusion intermittent feeding (SIIF) can reduce respiratory deterioration during gavage feeding in preterm infants in the NICU. @*Methods@#Data on preterm infants whose gavage feeding method was changed to SIIF (1-­­hour infusion with an infusion pump and 2-­hour rest within a 3­-hour interval) from bolus gravity feeding (2-­ or 3-­hour interval) due to feeding­-associated cardiorespiratory deterioration were retrospectively reviewed. A significant cardiorespiratory event was defined as a saturation level below 80% or heart rate below 80 bpm. We compared the frequency of cardiorespiratory events and the level of respiratory support 24 hours before and after the application of SIIF. @*Results@#A total of 34 infants were enrolled and analyzed. The total frequency of desaturation or bradycardia significantly decreased after SIIF application (8.94 vs. 5.03, P=0.001). The frequency of feeding-­related bradycardia and desaturation also significantly decreased (4.15 vs. 1.68, P=0.008). Out of 34 patients, 11 (32.4%) had a decreased level of ventilator support within 1 day after SIIF. The respiratory severity scores of the 10 patients who received invasive ventilator support decreased significantly after SIIF (5.24 vs. 4.59, P=0.032). @*Conclusion@#SIIF significantly decreased gavage feeding­-associated cardiorespiratory events and reduced respiratory support in approximately one-­third of subjects. Therefore, SIIF may be a therapeutic option for gavage feed-­associated respiratory deterioration in preterm infants in the NICU.

Cholesterol side-chain cleavage enzyme deficiency caused by a novel homozygous variant in P450 sidechain cleavage enzyme gene (CYP11A1) in a 46,XX Korean girl

The CYP11A1 gene encodes for the cholesterol side-chain cleavage enzyme (P450scc), which initiates steroid hormone biosynthesis. Defective P450scc activity results in severe glucocorticoid and mineralocorticoid deficiencies. We describe a case of P450scc deficiency due to a novel homozygous CYP11A1 variant inherited from the mother with a possibility of uniparental disomy (UPD). The patient was a female, had no family history of endocrine disease, and showed adrenal insufficiency at 13 days of age. Hormonal analysis with an adrenocorticotropic hormone stimulation test showed both glucocorticoid and mineralocorticoid deficiencies, presumed to be a defect of the early stage of steroidogenesis. Exome sequencing reported a novel homozygous frameshift variant of CYP11A1 (c.284_285del, p.Asn95Serfs*10), which was inherited from the mother.Additionally, homozygosity in 15q22.31q26.2, which included CYP11A1, was identified using a chromosomal microarray. It was suggested that the possibility of maternal UPD was involved as the cause of a P450scc deficiency by unmasking the maternally derived affected allele. To our understanding, P450scc deficiency associated with UPD encompassing CYP11A1 had not been reported in Korea before. Genetic analysis can help diagnose rare causes of primary adrenal insufficiency, including P450scc deficiency.

Associations between Maternal sFlt-1/PlGF Ratio and Perinatal and Neonatal Outcomes in Newborns Born to Mothers with Preeclampsia

Purpose@#The ratio of soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF) is considered a predictive marker of preeclampsia. However, the relationship between the sFlt-1/PlGF ratio and perinatal and neonatal outcomes remains unknown. This study aimed to determine the associations of the sFlt-1/PlGF ratio with perinatal and neonatal outcomes in newborns born to mothers with preeclampsia. @*Methods@#This retrospective cohort study reviewed singleton neonates born to mothers with preeclampsia who underwent testing for the sFlt-1/PlGF ratio. We investigated the relationship between maternal sFlt-1/PlGF ratios and gestational age (GA), birth weight (Bwt), Bwt z-score, morbidities, and mortality of neonates born to mothers tested for the sFlt-1/PlGF ratio. Maternal sFlt-1/PlGF ratios examined within 30 days before delivery were used for analysis. Neonatal morbidities and mortality were investigated only in preterm infants born earlier than 32 weeks GA. @*Results@#A total of 225 neonates were included, of which 163 (72.4%) were preterm infants. GA (R=– 0.577, p<0.001), Bwt (R=–0.713, p<0.001), and Bwt z-score (R=–0.608, p<0.001) exhibited significant negative correlations with the sFlt-1/PlGF ratios. Among the 50 preterm infants born earlier than 32 weeks GA, neonatal morbidities were not significantly associated with the sFlt-1/PlGF ratio after adjusting for GA and Bwt. @*Conclusion@#In mothers with preeclampsia, a higher sFlt-1/PlGF ratio was associated with the delivery of newborns with lower GA and lower Bwt. However, this ratio was not associated with increased morbidity or mortality in premature infants born earlier than 32 weeks GA.

Source Investigation and Control of Ralstonia mannitolilytica Bacteremia in a Neonatal Intensive Care Unit: A Case Report

A case of persistent Ralstonia mannitolilytica bacteremia in the neonatal intensive care unit prompted source investigation due to its rarity. After an extensive investigation, a contaminated ultrasonic nebulizer was identified as the source, and the infection was controlled by removing the source. This study emphasizes the importance of further investigations, even in single cases of rare pathogens.

The Effect of Incompletely Administered Antenatal Corticosteroids on Neonatal Pulmonary Outcomes in Late Preterm Infants

Purpose@#Recent obstetric guidelines recommend the administration of antenatal corticosteroids in pregnant women at risk of delivering infants at a gestational age between 34 and 36 weeks. We examined the effect of incompletely administered antenatal corticosteroids on the neonatal pulmonary outcomes in late preterm infants. @*Methods@#Late preterm infants (34+0 to 36+6 weeks gestational age) born at the Seoul National University Bundang Hospital from January 2019 to June 2020 were retrospectively enrolled. We excluded multiple births except twins, those with major congenital anomalies, deaths, or transfers to other hospitals. An incomplete course of antenatal corticosteroids was defined as one in which the first or the second dose of betamethasone was administered within 24 hours before delivery. The rates of neonatal pulmonary morbidities were compared between late preterm infants given incomplete courses antenatal corticosteroids and their peers who not given antenatal corticosteroids; these morbidities included respiratory distress syndrome and transient tachypnea of the newborn, assisted ventilation including invasive mechanical ventilation, nasal continuous positive airway pressure and high-flow nasal cannula, and admission to neonatal intensive care unit. @*Results@#Logistic regression models were constructed while adjusting for factors which were significant in bivariate models. After adjusting for baseline maternal and neonatal characteristics, we found no significant differences in the rates of neonatal pulmonary morbidities, assisted ventilation, or admission to the neonatal intensive care unit between late preterm infants who received incomplete antenatal corticosteroid therapy and their peers who were not given any antenatal corticosteroids. @*Conclusion@#Incompletely administered antenatal corticosteroids did not significantly alter the neonatal pulmonary outcomes in late preterm infants.

First Successful Application of Preimplantation Genetic Diagnosis for Lethal Neonatal Rigidity and Multifocal Seizure Syndrome in Korea: A Case Report

Lethal neonatal rigidity and multifocal seizure syndrome (RMFSL) is a severe autosomal recessive epileptic encephalopathy characterized by rigidity, intractable multifocal seizures, microcephaly, apnea, and bradycardia immediately after birth. RMFSL is related to a mutation in breast cancer 1-associated ataxia telangiectasia mutated activation-1 protein (BRAT1). We report a case of a female infant born to non-consanguineous Korean parents who developed hypertonia, dysmorphic features, progressive encephalopathy with refractory seizures at birth, and worsening intermittent apnea, leading to intubation and death at 137 days of age. The initial repeated electroencephalographic findings were normal; however, a pattern of focal seizures emerged at 35 days of life. Rapid trio whole-exome sequencing revealed heterozygous mutations c.1313_1314delAG p.(Gln438Argfs*51) and c.1276C>T p. (Gln426*) in BRAT1. After genetic counseling for pregnancy planning, a preimplantation genetic diagnosis for targeted BRAT1 mutations was successfully performed, and a healthy baby was born. To our knowledge, this is the first reported case of a Korean patient with compound heterozygous mutations in BRAT1. An early and accurate genetic diagnosis can help provide timely treatment to patients and indicate the need for reproductive counseling for parents for family planning.

Factors Associated with Clinical Response to Low-Dose Dexamethasone Therapy for Bronchopulmonary Dysplasia in Very Low Birth Weight Infants

Purpose@#To identify factors associated with the clinical response to low-dose dexamethasone therapy (LDDT) in preterm infants for bronchopulmonary dysplasia (BPD). @*Methods@#We used a retrospective medical record review to evaluate preterm infants who were born before 32 weeks of gestation or with a birth weight less than 1,500 g. All infants were admitted to the neonatal intensive care unit at a tertiary academic hospital between January 2010 and June 2019, and received LDDT for BPD. The preterm infants’ respiratory severity scores (RSS) were calculated from the first day of LDDT to the day of extubation, or the last day of LDDT. A good response was defined as a decreasing RSS with a slope greater than 0.181. A poor response was defined as a non-decreasing RSS, or a decreasing RSS with a slope less than 0.181 during LDDT. A total dose of 1.1 mg/kg was administered for 10 days for each single course of LDDT. @*Results@#A total of 51 preterm infants were included in the final analysis. Thirty preterm infants (58.8 %) were in the good response group, and 21 preterm infants (41.2%) were in the poor response group. There were no significant differences in gestational age, birth weight, and sex between the good response group and poor response group. Preterm premature rupture of membrane and histologic chorioamnionitis were significantly associated with a poor response to LDDT. Higher RSS on the first day of the LDDT was associated with a good response to LDDT. @*Conclusion@#Antenatal infection and/or inflammation may be associated with an unfavorable response to postnatal LDDT for BPD. Preterm infants with more severe respiratory failure seem to benefit more from LDDT for BPD.

Strategies to improve outcomes of bronchopulmonary dysplasia / 소아과

No abstract available.

Three Cases of Pierre Robin Sequence with Upper Airway Obstruction Relieved by Nasopharyngeal Airway Insertion

Pierre Robin sequence (PRS), also called Robin sequence, is a congenital anomaly characterized by a triad of micrognathia, glossoptosis, and upper airway obstruction. Infants with PRS can present with varying degrees of respiratory difficulty secondary to upper airway obstruction. There has been no consensus for the treatment of upper airway obstruction in infants with PRS, but recent studies recommend attempting non-surgical interventions before surgical treatment. In this case report, we present 3 cases of infants diagnosed with PRS who showed persistent respiratory difficulties after birth. Before considering surgical intervention, insertion of a nasopharyngeal airway was attempted in these infants. Following this procedure, symptoms of upper airway obstruction were relieved, and all infants were discharged without surgical interventions; the nasopharyngeal airway was removed 1 to 2 months later. To date, no infant has shown signs of upper airway obstruction. Nasopharyngeal airway insertion is a highly effective and less invasive treatment option for infants with PRS. However, it is not widely known and used in Korea. Nasopharyngeal airway insertion can be preferentially considered before surgical intervention for upper airway obstruction in such infants.

Clinical Features of Late-Onset Circulatory Collapse in Preterm Infants

PURPOSE: This study aimed to investigate the incidence and clinical features of late-onset circulatory collapse (LCC) in preterm infants. METHODS: Medical records of 327 preterm infants (born before 32 gestational weeks) admitted to the neonatal intensive care unit of Seoul National University Bundang Hospital between January 2014 and December 2017 were reviewed. LCC was defined as sudden onset of refractory hypotension occurring after 7 days of life without obvious causes, which responded to glucocorticoid administration. Clinical characteristics and outcomes in infants with LCC were compared with those in infants with hypotension associated with identifiable causes, which developed after 7 days of life. RESULTS: Among 327 preterm infants who enrolled in this study, 65 infants developed hypotension with oliguria after 7 days of life. Among these 65 infants, 35 (53.8%) met the criteria for LCC and 30 (46.2%) were diagnosed with hypotension associated with other identifiable causes. No statistically significant differences were observed in the baseline pre- and perinatal characteristics between infants with LCC and those with hypotension associated with other causes. Infants with hypotension associated with other causes showed a higher mortality rate than those with LCC (33.3% vs. 5.7%, P=0.004). The mean gestational age and birth weight of infants with LCC were 27+5±2+1 weeks and 963±245 g, respectively. LCC occurred at a mean postnatal age of 18 days. The median body weight at the time of diagnosis of LCC was 1,200 g. No association was observed between LCC and gestational age. CONCLUSION: Among preterm infants born before 32 gestastional weeks who developed hypotension after 7 days of life, nearly 50% were diagnosed with LCC without apparent identifiable causes. Infants with LCC showed a lower mortality rate than those with hypotension associated with other causes.

A Case of Zenker's Diverticulum Mimicking a Right Side Thyroid Nodule

Zenker's diverticulum, a pulsion diverticulum of the hypopharynx, is a rare lesion that commonly occurs in left side of hypopharynx. The incidence of esophageal diverticula is much lower than that of focal lesions or nodules of thyroid. In an ultrasonography, the outpouching just like a focal thyroid lesion, may present as an oval or circular structure. The food remnants or gas bubbles present in the diverticulum may mimic microcalcifications presented in papillary thyroid carcinoma. We reported a case of right side Zenker's diverticulum mimicking a thyroid cancer in thyroid ultrasonography.

Antenatal Corticosteroids and Clinical Outcomes of Preterm Singleton Neonates with Intrauterine Growth Restriction

PURPOSE: We assessed the influence of antenatal corticosteroid (ACS) on the inhospital outcomes of intrauterine growth restriction (IUGR) infants. METHODS: A retrospective study was conducted with singletons born at 23⁺⁰ to 33⁺⁶ weeks of gestation at Seoul National University Hospital from 2007 to 2014. We compared clinical outcomes between infants who received ACS 2 to 7 days before birth (complete ACS), at 7 days (incomplete ACS), and those who did not receive ACS in IUGR and AGA infants. Multivariate logistic regression using Firth's penalized likelihood was performed. RESULTS: 304 neonates with 91 IUGR neonates were eligible. Among AGA neonates, mortality (adjusted odds ratio [aOR], 0.13; 95% confidence interval [CI], 0.02 to 0.78), hypotension within 7 postnatal days (aOR, 0.20; 95% CI, 0.06 to 0.64), and severe bronchopulmonary dysplasia (BPD) or death (aOR, 0.24; 95% CI, 0.07 to 0.77) were lower in complete ACS group after adjusting for pregnancy induced hypertension and uncontrolled preterm labor. Mortality (aOR, 0.18; 95% CI, 0.04 to 0.78), hypotension (aOR, 0.26; 95% CI, 0.09 to 0.70), and severe BPD or death (aOR, 0.33; 95% CI, 0.12 to 0.92) were also lower in the incomplete ACS group. Among IUGR infants, after adjusting for birth weight and 5-minute Apgar score, inhaled nitric oxide use within 14 postnatal days was lower in both complete ACS (aOR, 0.07; 95% CI, 0.01 to 0.67) and incomplete ACS (aOR, 0.04; 95% CI, 0.01 to 0.37) groups. CONCLUSION: ACS was not effective in reducing morbidities in IUGR preterm infants.

RNA-Seq for Gene Expression Profiling of Human Necrotizing Enterocolitis: a Pilot Study

Necrotizing enterocolitis (NEC) characterized by inflammatory intestinal necrosis is a major cause of mortality and morbidity in newborns. Deep RNA sequencing (RNA-Seq) has recently emerged as a powerful technology enabling better quantification of gene expression than microarrays with a lower background signal. A total of 10 transcriptomes from 5 pairs of NEC lesions and adjacent normal tissues obtained from preterm infants with NEC were analyzed. As a result, a total of 65 genes (57 down-regulated and 8 up-regulated) revealed significantly different expression levels in the NEC lesion compared to the adjacent normal region, based on a significance at fold change ≥ 1.5 and P ≤ 0.05. The most significant gene, DPF3 (P < 0.001), has recently been reported to have differential expressions in colon segments. Our gene ontology analysis between NEC lesion and adjacent normal tissues showed that down-regulated genes were included in nervous system development with the most significance (P = 9.3 × 10⁻⁷; P(corr) = 0.0003). In further pathway analysis using Pathway Express based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, genes involved in thyroid cancer and axon guidance were predicted to be associated with different expression (P(corr) = 0.008 and 0.020, respectively). Although further replications using a larger sample size and functional evaluations are needed, our results suggest that altered gene expression and the genes' involved functional pathways and categories may provide insight into NEC development and aid in future research.

Chorioamnionitis: Is a major player in the development of bronchopulmonary dysplasia? / 소아과

Chorioamnionitis is an inflammation in the fetal membranes or placenta. When chorioamnionitis develops, fetal lungs are exposed to inflammatory cytokines and mediators via amniotic fluid. Because inflammation plays a pivotal role in the development of bronchopulmonary dysplasia (BPD), a chronic lung disease of prematurity, fetal lung inflammation induced by chorioamnionitis has been considered to be one of the major pathogenetic factors for BPD. Although there have been a number of studies that demonstrated the relationship between chorioamnionitis and BPD, there are still controversies on this issue. The controversies on the relationship between chorioamnionitis and BPD arise from not-unified definitions of chorioamnionitis and BPD, different study populations, and the proportion of contribution between inflammation and infectious microorganisms. The publication bias also contributes to the controversies. Clinical trials targeting chorioamnionitis or microorganisms that cause chorioamnionitis will answer on the actual relationship between chorioamnionitis and BPD and provide a novel prophylactic strategy against BPD based on that relationship.

Comparison of the Mortality and In-Hospital Outcomes of Preterm Infants Treated with Ibuprofen for Patent Ductus Arteriosus with or without Clinical Symptoms Attributable to the Patent Ductus Arteriosus at the Time of Ibuprofen Treatment

The aim of this study was to assess the differences in the mortality and in-hospital outcomes of preterm infants with < 28 weeks of gestation who received ibuprofen treatment according to the presence of clinical symptoms (any of oliguria, hypotension, or moderate to severe respiratory difficulty) attributable to hemodynamically-significant patent ductus arteriosus (hsPDA) at the time of first ibuprofen treatment. In total, 91 infants born from April 2010 to March 2015 were included. Fourteen infants (15.4%) received ibuprofen treatment when there were clinical symptoms due to hsPDA (clinical symptoms group). In clinical symptoms group, infants were younger (25 [23–27] vs. 26 [23–27] weeks; P = 0.012) and lighter (655 [500–930] vs. 880 [370–1,780] grams; P < 0.001). Also, the clinical risk index for babies (CRIB)-II scores were higher and more infants received invasive ventilator care ≤ 2 postnatal days. More infants received multiple courses of ibuprofen in clinical symptoms group. Although the frequency of secondary patent ductus arteriosus (PDA) ligation and the incidence of bronchopulmonary dysplasia (BPD) was higher in the clinical symptoms group in the univariate analysis, after multivariate logistic regression analysis adjusting for the CRIB-II score, birthweight, birth year, and the invasive ventilator care ≤ 2 postnatal days, there were no significant differences in mortality, frequency of secondary ligation and in-hospital outcomes including necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), BPD or death. Our data suggest that we can hold off on PDA treatment until the clinical symptoms become prominent.

A Case of Congenital Lymphatic Dysplasia Complicated by Hydrops Fetalis

Congenital lymphatic dysplasia is a rare congenital maldevelopment of the lymphatic system, in which dysfunction of the lymphatic system may cause leakage of lymph fluid into the limbs and the pleural, pericardial, or peritoneal cavity. We experienced a case of hydrops fetalis with subcutaneous lymphedema, chylothorax, chylous ascites and pericardial effusion. Lymphangiography revealed a critical defect of lymphatic system. Here, we report the first case of premature infant with congenital lymphatic dysplasia confirmed by lymphangiography, which is the first reported in Korea.

Decreased Incidence of Necrotizing Enterocolitis after Introduction of Exclusive Breast Milk Feeding in a Single Neonatal Intensive Care Center

PURPOSE: To evaluate the effects of exclusive breast milk feeding (BMF) on the incidence of necrotizing enterocolitis (NEC) in preterm infants. METHODS: All newborn infants, born at <32 weeks of gestation and weighing <1,500 g, admitted to the neonatal intensive care center at Seoul National University Bundang Hospital during the study period, were included. The study was divided into period I: pre-exclusive BMF (January 2010–March 2014) and period II: exclusive BMF (April 2014–December 2016). RESULTS: A total of 374 infants were enrolled in this study, with 174 in period I and 174 in period II. The incidence of NEC was 11.5% in period I and 3.4% in period II. As the mean gestational age and birth weight were significantly greater in infants in period II, the difference in the incidence of NEC between the two periods was adjusted by gestational age. After adjustment, the incidence of NEC in period II was significantly lower than in period I (P=0.024). CONCLUSION: Exclusive BMF significantly reduced the incidence of NEC in a single neonatal intensive care center.

Bronchial Artery Aneurysm Presenting Hemoptysis, Initially Mis-diagnosed as Bronchial Arterio-venous Malformation: A Case Report

Normal bronchial arteries are small vessels that arise mostly from the descending thoracic aorta. Bronchial artery aneurysm is defined as a dilatation of the bronchial arteries with a diameter over 2 mm, and is reported in less than 1% of bronchial arterial angiography. A 70-year-old male patient was presented with hemoptysis. He had been treated for pulmonary tuberculosis 50 years ago. He also had a history of admission with hemoptysis 10 years ago, for which he was diagnosed as bronchiectasis on computed tomography imaging. Upon arrival to our hospital, abnormal vascular structure was detected on the mediastinum, arising from the descending thoracic aorta. It was dilated to 14 mm with a saccular form. Initially, we evaluated the structure as a bronchial arteriovenous malformation because it seemed to be drained into the pulmonary vein directly. For further evaluation, he had received a trans-catheter bronchial artery angiography. Both bronchial arteries were hypertrophied, but direct arteriovenous shunt was not detected; as such, we concluded this structure to be bronchial artery aneurysm. We performed embolization for both bronchial arteries and filled the aneurysm with coiling. He had no recurrence of hemoptysis and was discharged on 4 days post embolization. Our case reports an incidental bronchial artery aneurysm, which was initially misdiagnosed as bronchial arteriovenous anomaly, and finally treated with embolization and coiling.

Venous thromboembolism in pediatric patients: a single institution experience in Korea

BACKGROUND: While venous thromboembolism (VTE) is uncommon, its incidence is increasing in children. We aimed to evaluate the incidence, risk factors, treatment, and outcome of pediatric VTE cases at a single tertiary hospital in Korea. METHODS: We retrospectively analyzed the records of consecutive pediatric VTE patients admitted to the Seoul National University Bundang Hospital between April 2003 and March 2016. RESULTS: Among 70,462 hospitalizations, 25 pediatric VTE cases were identified (3.27 cases per 10,000 admissions). Fifteen patients (60%) were male, 8 were neonates (32%), and the median age at diagnosis was 10.9 years (range, 0 days‒17 yr). Doppler ultrasonography was the most frequently used imaging modality. Thrombosis occurred in the intracerebral (20%), upper venous (64%), lower venous (12%), and combined upper and lower venous systems (4%). Twenty patients (80%) had underlying clinical conditions including venous catheterization (24%), malignancy (20%), and systemic diseases (12%). Protein C, protein S, and antithrombin deficiencies occurred in 2 of 13, 4 of 13, and 1 of 14 patients tested, respectively. Six patients were treated with heparin followed by warfarin, while 4 were treated with heparin or warfarin. Thrombectomy and inferior vena cava filter and/or thrombolysis were performed in 5 patients. Two patients died of pulmonary embolism, and 2 developed a post-thrombotic syndrome. CONCLUSION: Compared with the reports from Western countries, VTE occurrence was lower in the Korean pediatric population under study, although similar clinical characteristics including bimodal age distribution, underlying diseases, treatment pattern, and outcomes were observed.