Type 4 renal tubular acidosis (RTA) is an uncommon but clinically significant complication in kidney transplant recipients, leading to hyperkalemia and non-anion gap metabolic acidosis due to aldosterone deficiency or resistance. Calcineurin inhibitors, especially tacrolimus, can contribute to this disorder by impairing distal tubular potassium secretion. We describe a 47-year-old male who underwent living donor kidney transplantation from his biological mother. Despite good early graft function, he developed severe recurrent hyperkalemia, requiring hemodialysis on postoperative days 11 and 23. Laboratory evaluation revealed non-anion gap metabolic acidosis (anion gap 10.8 mEq/L), urine pH 5.5, and a low transtubular potassium gradient of 2.5, consistent with type 4 RTA. At diagnosis, serum creatinine was 1.39 mg/dL (estimated glomerular filtration rate, 54.8 mL/min/1.73 m 2 ). The patient was treated with fludrocortisone (starting at 0.2 mg/day and tapered to 0.05 mg/day), a thiazide diuretic (12.5 mg twice daily), and reduction of tacrolimus dose with addition of sirolimus (2.5 mg/day). Electrolyte abnormalities resolved, and graft function remained stable without rejection. This case underscores the importance of recognizing tacrolimus-induced type 4 RTA early and using individualized treatment strategies to correct hyperkalemia and preserve allograft function.

Varicella, caused by the varicella-zoster virus, was once nearly universal in childhood before the advent of vaccination and may lead to severe complications and even fatalities. Monitoring varicella vaccine effectiveness is crucial yet often overlooked in settings with limited surveillance infrastructure. The Korean Varicella Immunization Monitoring (K-VIM) Scheme was established to address this gap by assembling a national, insurance-based birth cohort of children born between 2011 and 2022 (n=4,505,165). This cohort leverages comprehensive healthcare databases in Korea to capture vaccination records, medical visits, and varicella infection outcomes for virtually all children within the target birth years. We describe the enrollment and key characteristics of the K-VIM cohort, including vaccination coverage, demographic features, and varicella incidence to date. The structure and completeness of Korea’s national health insurance and immunization registries enable robust longitudinal tracking of varicella infections among vaccinated versus unvaccinated children. Early findings demonstrate distinct patterns in infection rates and disease severity according to vaccination status. The K-VIM Scheme provides a foundation for ongoing epidemiological studies of varicella vaccine effectiveness and public health impact in Korea. Future plans include evaluating the long-term effects of varicella vaccination, including potential impacts on herpes zoster incidence, using diverse study designs to strengthen causal inference and inform immunization policy.

In patients with differentiated thyroid cancer (DTC), initial recurrence risk stratification based on clinical, histopathological, and perioperative data remains the key determinant for guiding management strategies during the first 1-2 years post-treatment. However, the adoption of ongoing risk stratification (ORS), which dynamically reassesses risk by integrating longitudinal clinical data and treatment response, enables more precise long-term prognostic assessment and facilitates highly individualized management. Building upon recent guidelines, the 2026 KTA guideline has been further refined by incorporating robust evidence from large-scale national cohorts and comprehensive systematic reviews. These updated recommendations outline contemporary concepts of ORS, risk-adapted TSH suppression targets, optimized surveillance modalities for recurrence detection, and disease-specific long-term follow-up strategies. Reflecting the paradigm shift toward de-escalated treatment, this revision integrates evolved perspectives on TSH suppression intensity, the clinical interpretation of thyroglobulin levels, and tailored follow-up intervals. These evidence-based recommendations aim to minimize unnecessary treatment and excessive surveillance in the large proportion of patients with excellent prognosis after initial therapy, while ensuring that each patient receives appropriately tailored and effective long-term management.

Acute lymphoblastic leukemia (ALL) primarily affects the bone marrow and peripheral blood. Extramedullary manifestations, especially in the sinonasal cavity, are rare and difficult to diagnose. We report a case of B-cell ALL in a 4-year-old girl who initially presented with a sinonasal mass mimicking a primary malignant neoplasm. The patient developed right eye protrusion upon nasal blowing over a period of 2 weeks. Imaging studies revealed an aggressive-appearing mass in the right maxillary sinus with extensive local invasion. The radiologic differential diagnosis included rhabdomyosarcoma, lymphoma, and other pediatric sinonasal malignancies. Histopathologic examination of the biopsy specimen and subsequent bone marrow evaluation established the diagnosis of B-cell ALL with BCR/ABL1 fusion. This case highlights the importance of including ALL in the differential diagnosis of sinonasal masses in pediatric patients, particularly when imaging features suggest an aggressive malignancy accompanied by hematologic abnormalities. A comprehensive evaluation, including imaging studies, routine laboratory tests, tissue biopsy, and bone marrow examination, is crucial for establishing an accurate diagnosis and initiating appropriate treatment.

Objective: This study compared clinical and cosmetic outcomes of cranioplasty using customized three-dimensional (3-D) printed implants versus autologous bone in patients with aneurysmal subarachnoid hemorrhage (aSAH) after decompressive craniectomy (DC). Methods: We retrospectively reviewed 50 patients who underwent cranioplasty after DC for aSAH between July 2018 and December 2023. Patients were divided into the three-dimensional cranioplasty(3-DC, n=26) and autologous bone cranioplasty (AC, n=24) groups. Demographics, aneurysm characteristics, surgical parameters, morphometric analysis of defect coverage, complications, and functional outcomes assessed by the modified Rankin Scale (mRS) were compared. Results: A total of 54 hemispheres underwent cranioplasty. Compared with AC, the 3-DC group had larger defects but achieved higher coverage (96.7% vs. 93.4%, p=0.044) and smaller residual defects (338.7±274.2 mm² vs. 528.5±331.3 mm², p=0.049). Complication rates were lower in 3-DC (9 cases) than AC (15 cases, p=0.0994). Wound dehiscence and fluid collection were more frequent with 3-DC, while bone flap resorption and epidural abscess occurred only with AC. Revision surgery was required in six patients, five initially treated with autologous bone. Neurological outcomes (mRS) were maintained or improved in both groups. Conclusions In aSAH patients undergoing cranioplasty after DC, customized 3-D printed implants achieved significantly better anatomical restoration and showed a numerical trend toward fewer complications compared with autologous bone. While AC remains feasible, its risks of resorption and infection often necessitate revision. 3-D printed implants may be considered a reasonable alternative, particularly in aSAH patients at higher risk of complications.

Salvage surgery is an emerging option for carefully selected patients with advanced epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) whose disease remains controlled on tyrosine kinase inhibitor (TKI) therapy. Fourteen retrospective series report median progression-free survival (PFS) of 14–52 months and overall survival (OS) often exceeding 3 years, suggesting better disease control than continued TKI therapy alone. Although PFS generally improves, some cohorts show no OS advantage, probably because effective post-progression treatments dilute survival differences. Non-surgical local consolidative therapies remain essential for oligometastatic disease; nevertheless, resection yields intact specimens for comprehensive pathologic and molecular analysis.Access to tissue permits earlier identification of resistance mechanisms—most commonly the T790M mutation—more accurate prognostication, and more precise systemic-therapy selection. Comprehensive sampling can also identify histologic transformation and compound mutations that precede radiologic progression. Adverse prognostic factors include older age, high preoperative carcinoembryonic antigen levels, advanced pathological T stage, programmed death-ligand 1 ≥1%, and spread through air spaces. Salvage surgery is feasible and effective in carefully selected patients, especially those with oligoresidual disease and favorable tumor biology. Patient selection should integrate performance status, anatomic extent, histopathology, and genomic profile through multidisciplinary discussions. Despite regional differences (e.g., higher EGFR-mutation prevalence and wider adoption of minimally invasive approaches in East Asia) oncologic outcomes are comparable when selection criteria are applied consistently. Prospective trials are warranted to validate these retrospective observations, refine selection algorithms, establish optimal timing, and clarify how surgery can best be integrated with next-generation targeted agents and immunotherapies.

Objectives: This study aimed to quantify the actual resource utilization and cost structure of homevisit oral health care services using a Time-Driven Activity-Based Costing (TDABC) approach, in response to the growing demand for efficient home-based care for older adults. Methods: An analytical framework comprising 12 domains and 78 activities, validated through a Delphi study, was applied to home‑visit oral health care records. A total of 100 home‑visit service logs recorded by ten dental hygienists participating in an integrated care program in Cheonan City between March and April 2024 were analyzed. Data collected included activity time, consumable supply, travel time and distance, and transportation expenses. A capacity cost rate incorporating both direct and indirect costs was used to estimate activity‑level costs and total costs per visit. Results: Dental hygienists conducted an average of 6.43 visits per day. The mean travel time and distance per visit were 15.04 min and 7.31 km, respectively. Transportation expenses averaged 9,740 KRW per visit, and consumable supply costs ranged from 1,428 to 9,738 KRW per patient, depending on oral health status. The calculated capacity cost rate was 487 KRW/min, resulting in activity-based costs of 66,232 KRW per visit across the 78 activities. When transportation time costs were added (7,324 KRW; 15.04 min×487 KRW/min), the total cost per visit was estimated at 73,556 KRW. Preparation and infection control activities were identified as major cost drivers. Conclusions The TDABC approach provided a comprehensive estimate of the cost structure of home-visit oral health care services, capturing expenditures associated with travel, preparation, and documentation. These findings provide evidence to support sustainable reimbursement models within long-term care and integrated care systems.

Purpose: This study aimed to develop and implement an antimicrobial stewardship education program for physician assistant nurses and to evaluate its effects on their knowledge and clinical performance. Methods: A quasi-experimental, single-group pre-post design was conducted with 50 physician assistant nurses at a university hospital in Seoul, Republic of Korea. The antimicrobial stewardship education program, developed using the ADDIE model, consisted of 12 sessions including lectures and case-based learning (CBL)-based discussions.Knowledge was measured before and immediately after the intervention, while performance was assessed pre-intervention and four weeks post-program. Data were analyzed using paired t-tests, Wilcoxon signed-rank tests, and analysis of covariance (ANCOVA). Results: Knowledge scores significantly improved from 44.65±7.45 to 58.50±10.11 (p<.001), and all subdomains showed significant increases (p<.001). Performance scores increased from 3.68±0.77 to 4.28±0.68 (p<.001). Knowledge gain did not differ significantly between the medical and surgical departments (p=.710). Likewise, after adjusting for pre-test scores, no significant difference in performance improvement was observed between the two departments (ANCOVA, p=.170). These results indicate that the program was effective across both departments regardless of their characteristics. Conclusion The antimicrobial stewardship education program improved both knowledge and performance among physician assistant nurses. This program may contribute to the standardization of antimicrobial stewardship education and to appropriate antimicrobial use and the reduction of antimicrobial resistance.

Purpose: This study compared the efficacy of different irrigation methods for the removal of Ca(OH)2 paste from the root canal. Materials and Methods: The root canals of 75 human mandibular premolars with standardized 15-mm canal lengths were prepared using nickel-titanium rotary files. After drying, the canals were filled with Ca(OH)2 paste. The teeth were divided into five groups: Control group (Group C), conventional irrigation; Group EA, sonic activation (EndoActivator); Groups EQA and EQB, sonic activation (EQ-S with metal tips A and B, respectively); and Group EU, ultrasonic activation (EndoUltra).The Ca(OH)2 paste volume before and after irrigation was measured using micro-computed tomography (CT) images. One specimen from each group was bisected along the long axis, and the canal walls were evaluated at 100× magnification using a scanning electron microscope. Statistical analyses were performed using Kruskal-Wallis and Mann-Whitney U tests. Results: Overall, Ca(OH)2 paste removal was higher in Group EQA than in Group C. In the coronal third, removal rate was higher in Group EQA than in Group C. In the middle third, Groups EQB and EU outperformed Group C. Removal from the apical third was higher in Group EQA than in Group C. All groups showed greater removal from the coronal and middle thirds than from the apical third. Conclusion Sonic and ultrasonic irrigation methods demonstrated higher efficacy than conventional irrigation method for the removal of Ca(OH)2 paste from the root canal. All groups demonstrated better effectiveness in removal from the coronal and middle thirds than from the apical third.