Background: Erythema multiforme (EM) is typically a self-limited, acute hypersensitivity reaction. However, a subset of patients experiences chronic, recurrent episodes, for which clinical features and treatment strategies differ depending on the underlying etiology, especially in herpes simplex virus (HSV)-associated cases. Objective: To investigate the clinical and phenotypic features of chronic recurrent EM and assess treatment responses, with a focus on differences based on HSV association. Methods: This retrospective study included pathology-confirmed cases of suspected EM from 2010 to 2023. Forty patients with chronic EM (≥3 recurrences or persistent disease for ≥12 months) were included. Clinical, histopathologic, and serologic data were analysed.Patients were stratified into herpes simplex virus-associated erythema multiforme (HAEM) and non-HAEM groups. Clustering analysis was performed to identify clinical phenotypes.Treatment responses to antivirals and immunomodulators were evaluated. Results: Of the 40 patients, 24 (60%) were classified as HAEM. HAEM patients showed more mucosal involvement, smaller targetoid lesions, and acral predominance, while nonHAEM patients had larger, coalescing lesions with more trunk involvement. Cluster analysis supported HSV as the major discriminating factor. Antiviral agents were effective in 87.5% of HAEM cases but ineffective in 76.9% of non-HAEM patients. Immunosuppressants such as cyclosporine and mycophenolate mofetil showed variable responses. Baricitinib induced complete remission in all 3 refractory cases. Conclusion HSV association defines a distinct clinical subtype of chronic recurrent EM, with differences in lesion morphology, distribution, and treatment response. Recognizing these patterns may guide targeted therapeutic strategies, including the potential use of Janus kinase inhibitors in refractory cases.

Background: As nationwide government-led whole-genome sequencing (WGS) projects progress, optimizing the clinical integration of large-scale WGS results is crucial. We explored how the initial analysis from Korea’s First WGS Pilot Study for Rare Diseases was applied in clinical practice, and then we reanalyzed the data comprehensively at Samsung Medical Center (SMC) Seoul, Korea. Methods: A prospective cohort study designed to collect WGS data under a Korean national initiative was conducted from August 2020 to December 2021. We focused on patients with rare diseases recruited from 16 university hospitals. The participants included 5,000 individuals (2,200 probands and 2,800 family members). The initial WGS data and diagnostic reference reports (from 682 probands and 484 family members), generated based on the First Korean WGS Pilot Study for Rare Diseases, were subsequently reanalyzed by SMC. Results: The initial analysis of the First Korean WGS Pilot Study data revealed a diagnostic rate of 17%. Upon receiving these results, the SMC conducted two rounds of reanalysis, increasing the diagnostic rate from 15% in the first analysis, to 18% in the second, and finally to 24% in the third (P = 1.6 × 10 −5 ). Key factors in improving the genetic diagnosis included increased detection of novel (likely) pathogenic variants (P = 1.0 × 10 −4 ), improved diagnostic rates with larger family recruitment (P = 0.004), and refined clinical information for more precise genotype–phenotype correlation analysis (40%). Conclusions Although national WGS projects lay a foundation for rare disease diagnosis, hospital-level reanalysis and multidisciplinary collaborations are crucial for optimizing diagnostic outcomes.

Although splenomegaly is typically uncommon in myelodysplastic syndromes (MDS), it is associated with reduced engraftment rates and poor survival outcomes. Despite its clinical significance, the incidence and genetic associations of splenomegaly in MDS remain understudied. To address this, we conducted a retrospective study of 27 patients with MDS at the Veterans Health Service Medical Center in South Korea. Based on computed tomography scan evaluation, splenomegaly was identified in 26% of patients with MDS, and significant associations with variants in ASXL1 (P = 0.0089 for null and missense/inframe variants) and RUNX1 (P = 0.042 for null variants) were observed, suggesting that these variants are linked to an increased risk of splenomegaly. Notably, one patient with ASXL1 and TET2 variants developed severe splenomegaly (spleen size, 29 cm) following granulocyte colony-stimulating factor (G-CSF) treatment, requiring splenectomy. This case suggests a potential interaction between specific genetic variants and G-CSF sensitivity, potentially exacerbating splenomegaly. Our findings suggest that the incidence of splenomegaly in patients with MDS, including mild cases, is likely underestimated and that ASXL1 and RUNX1 variants increase the risk of splenomegaly. Furthermore, careful monitoring for the development of severe splenomegaly during G-CSF treatment may be warranted in genetically susceptible individuals with MDS.

Background: Mycoplasma pneumoniae is a major cause of community-acquired pneumonia (CAP) in children, with a rising incidence of macrolide resistance. Early diagnosis is crucial for reducing the disease burden; however, current diagnostic tools have limitations.We evaluated the diagnostic accuracy of serological assays and their performance based on symptom onset in children with CAP. Methods: From September 2023 to September 2024, we prospectively enrolled children with CAP, classified as M. pneumoniae pneumonia (MPP) or non-MPP, from 16 hospitals in Korea. Serological testing included chemiluminescence immunoassay (CLIA) and ELISA for detecting IgM and IgG, along with particle agglutination (PA) for total antibody measurements. Serological responses were analyzed at different times after symptom onset (0–4, 5–9, and 10–21 days). Results: Among 472 children with CAP (362 MPP, 110 non-MPP), 138 (29.2%) underwent PA testing, and 334 (70.8%) underwent IgM testing. PA at a 1:640 cutoff showed 48.0% sensitivity and 100% specificity. CLIA and ELISA showed comparable sensitivities (69.1% vs. 69.2%) and specificities (76.9% vs. 66.7%) for IgM testing. Seropositivity increased significantly with time since symptom onset (P for trend < 0.001), reaching 97.9% for IgM, 62.5% for IgG, and 94.7% for PA at 10–21 days. Conclusions The time post-symptom onset significantly influenced the diagnostic utility of serological tests for pediatric MPP, which showed limited value during the early stage of illness. These findings emphasize the importance of symptom onset-based interpretation of serological test results and their utility in complementing PCR when optimizing MPP diagnosis in children.

Background: This study aims to investigate the associations between work-related activities during free time, including frequency of working during free time and use of communication devices for work during free time, and sleep disturbance. It further explores the underlying mechanisms through mediation analysis. Methods: Data were analyzed from 21,473 participants of the seventh Korean Working Conditions Survey (KWCS, 2023). Multivariable logistic regression was employed to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for sleep disturbance. Three sequential models were constructed to evaluate the effects of weekly working hours and shift work on sleep disturbance risk. Mediation analysis was conducted to identify pathways linking work-related activities during free time and sleep disturbance. Results: Those who worked during their free time daily showed significantly higher risk of sleep disturbance (OR: 4.17; 95% CI: 2.64–6.58). Similarly, daily use of communication devices for work during free time was associated with an increased risk (OR: 1.83; 95% CI: 1.57–2.13). These associations remained robust even after adjusting for weekly working hours and shift work. Mediation analysis revealed that "worry about work while at home" was the primary mediator for device use (13.7%; 95% CI: 0.11–0.18), while "feeling too tired for housework after work" was the strongest mediator for working during free time (26.6%; 95% CI: 0.22–0.32). Conclusions The results indicate that engaging in work-related activities during free time elevates the risk of sleep disturbance, independent of long working hours or shift patterns. Mediation analysis revealed that the strongest effects were driven by the behavioral and psychological dimensions of work–family conflict. These findings suggest that sleep disturbance arises primarily from the erosion of work–life boundaries, fueled by persistent work-related rumination and the spillover of professional burdens into free time.

Background: This study investigated the relationship between work-life balance (WLB), effort-reward imbalance (ERI), and presenteeism among Korean wageworkers through two models used simultaneously. Methods: Data from the 6th Korean Working Conditions Survey for 28,669 Korean workers, including 13,513 men and 15,156 women, were analyzed. All analyses were performed with pre-designed weight. Multiple logistic regression analysis was used to analyze the association between WLB, ERI, and presenteeism among Korean workers. The participants were classified into the following four groups: group 1, status of both WLB and ERI is “balanced”; group 2, WLB and ERI status are “imbalanced” and “balanced”, respectively; group 3, WLB and ERI status are “balanced” and “imbalanced”, respectively; group 4: status of both WLB and ERI is “imbalanced.” Results: We found that WLB and ERI were associated with presenteeism in both men and women. Depending on their WLB and ERI status, women generally had a higher tendency of presenteeism than men. Multiple logistic regression shows that, in most models and groups, there is an increased odds ratio (OR) for presenteeism in both men and women compared to the reference value. Moreover, the OR in both men and women gradually increased in groups 2, 3, and 4 compared with group 1. When considering both WLB and ERI status simultaneously, ERI had a greater impact on presenteeism than WLB. Furthermore, it was found that a synergistic effect of presenteeism manifests when both WLB and ERI are in a state of imbalance simultaneously. Conclusions Using the two models simultaneously, we found an association between WLB, ERI, and presenteeism according to sex with a synergistic effect among Korean workers. Our research suggests that active interventions targeting WLB and ERI are necessary to reduce presenteeism, which ultimately leads to decreased productivity.

Purpose: Early differentiation between transient congenital hypothyroidism (TCH) and permanent congenital hypothyroidism (PCH) is crucial for optimizing the duration of treatment. This retrospective cohort study aimed to evaluate whether levothyroxine (LT4) dose requirements over time can predict TCH and guide earlier discontinuation of treatment. Methods: We retrospectively analyzed 105 infants with congenital hypothyroidism and normal thyroid glands confirmed by imaging at a single tertiary care center (Inha University Hospital) between January 2013 and December 2022. Patients were classified into TCH (n=70) or PCH (n=35) based on thyroid function after LT4 withdrawal at 3 years of age. LT4 dose/kg at 6, 12, and 24 months, along with clinical and biochemical parameters, were compared between the 2 groups. Receiver operating characteristic (ROC) curve analysis was used to assess the predictive performance of LT4 dose thresholds. Results: The LT4 dose was significantly lower in the TCH group at 6 (3.16±0.83 μg/kg vs. 3.75±0.99 μg/kg, P=0.005), 12 (2.51±0.82 μg/kg vs. 3.37±1.17 μg/kg, P<0.001), and 24 months (2.02±0.61 μg/kg vs. 3.09±1.19 μg/kg, P<0.001). ROC curve analysis showed an area under the curve (AUC) of 0.649, 0.746, and 0.794 at 6, 12, and 24 months, respectively. A logistic regression model incorporating LT4 dose, birth weight, and thyroid-stimulating hormone (TSH) levels improved prediction accuracy (AUC: 0.740, 0.782, 0.833 at 6, 12, and 24 months, respectively). Conclusion LT4 dose requirements at 6, 12, and 24 months serve as useful indicators for differentiating TCH from PCH. A combined predictive model incorporating LT4 dose, birth weight, and TSH levels may improve diagnostic accuracy, supporting earlier discontinuation of treatment.

Purpose: We aimed to compare the final adult height (FAH) of male patients with central precocious puberty (CPP) after treatment with a gonadotropin-releasing hormone agonist (GnRHa). Specifically, we compared FAH with the target height (TH) and the predicted adult height (PAH) before and after GnRHa treatment to quantify height gain and identify predictive factors. Methods: We retrospectively reviewed the medical records of 92 male patients with CPP and known FAH after GnRHa treatment at the Department of Pediatrics of Severance Children’s Hospital between January 2000 and June 2024. Results: The mean duration of GnRHa treatment was 2.7±1.3 years. A significant 1.1±0.9 years narrowing was observed in the difference between bone age (BA) and chronological age (CA) during treatment (P<0.001). TH was 172.4±3.4 cm. FAH was 173.6±6.4 cm. FAH was greater than TH by 1.2±5.9 cm (P=0.047). PAH before and after treatment was 179.9±8.1 and 181.2±7.4 cm, respectively. PAH was increased by 1.3±4.9 cm (P=0.012) after treatment. As the PAH standard deviation score (SDS) before GnRHa treatment increased, FAH tended to exceed TH. In contrast, higher testosterone levels before treatment are associated with FAH falling below TH. A longer duration of treatment and taller TH are associated with an FAH SDS greater than height SDS before treatment. Conversely, a greater weight SDS, BA–CA difference, and testis size before treatment are associated with FAH SDS being less than height SDS before GnRHa treatment. Conclusion GnRHa treatment improved FAH and inhibited bone maturation in male patients with CPP.

Purpose: Endoscopic submucosal dissection (ESD) has become a standard minimally invasive treatment for selected patients with early gastric cancer (EGC). This study presents the first nationwide survey of patients with EGC treated with ESD in 2023, conducted by the Korean College of Helicobacter and Upper Gastrointestinal Research. Materials and Methods: Data were retrospectively collected from participating referral centers across Korea using a standardized case report form covering patient characteristics, tumor features, procedural details, histopathological findings, and clinical outcomes.Descriptive and comparative analyses were conducted to summarize nationwide ESD practice patterns and outcomes. Results: Data from 5,460 ESD cases from 5,250 patients across 27 institutions were analyzed. The mean age was 67.4 years, with 74.1% males. Multiple synchronous lesions were identified in 3.7%. Most lesions were located in the lower third of the stomach (64.0%), and differentiated-type adenocarcinomas accounted for 87.8%. The en bloc and complete resection rates were 99.2% and 91.4%, respectively. Curative resection was achieved in 80.5%, whereas local non-curative resection (L-NCR) and surgical non-curative resection (S-NCR) were identified in 2.8% and 16.7%, respectively. Additional surgery was performed more frequently in patients with S-NCR than in those with L-NCR (59.3% vs. 24.7%). The bleeding and perforation rates were 3.6% and 0.9%, respectively, and were mostly managed conservatively or endoscopically. The median length of hospitalization was 4.0 days. Conclusions This first nationwide survey provides a comprehensive overview of the current practice of EGC treatment using ESD in Korea, demonstrating high technical success and safety, and establishing a baseline dataset for future longitudinal research.

Purpose: This study evaluated long-term trends in gastric cancer epidemiology and survival with a focus on conditional relative survival (CRS). Materials and Methods: Using the Korea Central Cancer Registry, we analyzed 665,184 patients who were newly diagnosed with gastric cancer between 1999 and 2022.The study period was divided into four intervals: Period I (1999–2005), Period II (2006–2011), Period III (2012–2017), and Period IV (2018–2022). Temporal trends in the incidence and mortality were assessed using crude and age-standardized rates. Relative survival was estimated using the Ederer II method, and the 5-year CRS was calculated according to the survival duration after diagnosis. Results: The incidence of gastric cancer increased until 2011 and subsequently declined, with a marked decrease observed in 2020. Individuals aged ≥70 years consistently had the highest incidence rates. Mortality rates showed a sustained decline throughout the study period. The overall 5-year relative survival improved from 69.8% in Period II to 78.4% in Period IV. The 5-year CRS increased from 86.1% at 1 year after diagnosis to 96.3% at 5 years.Patients with localized stage maintained a 5-year CRS above 95% at 1 year after diagnosis, whereas those with regional and distant stages showed 5-year CRS that consistently remained below 95%. Conclusions The incidence and mortality rates of gastric cancer in Korea have declined over the past two decades, accompanied by improved survival outcomes. The CRS analysis suggests that long-term follow-up is warranted, with the optimal duration varying according to patient characteristics.