Nagoya Journal of Medical Science

Although retroperitoneal sarcoma (RPS) is a rare malignancy, it is unlikely that a general surgeon would go through their career without encountering at least one case. Surgical resection remains the only potentially curative treatment and is performed in many institutions worldwide. However, given its low incidence, most centers manage only one or two cases annually, resulting in limited operative experience among surgeons. The clinical presentation of RPS varies widely depending on the tumor location and extent of invasion into adjacent organs and major vessels. This heterogeneity poses a challenge in standardizing surgical techniques and demands a high level of intraoperative adaptability. RPS is commonly found as large tumors, precluding the use of minimally invasive approaches, such as laparoscopy or robotic surgery. The retroperitoneal space also contains critical vascular structures, and inappropriate surgical approaches may lead to life-threatening hemorrhage. At Nagoya University Rare Cancer Center, numerous RPS surgeries have been performed. Through this experience, various technical considerations essential for safe and effective surgery were identified. This article introduces key operative strategies for RPS, including technical “knacks and pitfalls,” derived from extensive clinical experience with RPS surgery. Part 1 discusses general preparations that are specifically required for RPS surgery. Part 2 focuses on the details of the practical techniques of the RPS surgery. Finally, part 3 discusses resection of the tumor involving large retroperitoneal vessels, which need special preparations.

This article provides a detailed account of the practical techniques and precautions regarding the surgical resection of retroperitoneal sarcoma (RPS). As there is no standardized procedure for RPS surgery, the operative approach must be flexible, depending on tumor location and extent. Stepwise dissection from multiple directions is emphasized, as well as decision-making regarding combined resection of adjacent organs, such as the intestine, pancreas, kidney, liver, and adrenal gland. Strategies for managing tumor-associated feeding arteries and drainage veins to minimize intraoperative bleeding are also discussed. Nephrectomy is recommended when the tumor invades the renal hilum or adjacent structures; however, kidney preservation is considered whenever possible. The paper also addresses the extent of resection required, noting that in retroperitoneal liposarcoma, compartmental fat tissue removal is often preferred over strict margin-based resection, considering the high rate of microscopic infiltration. Distinguishing well-differentiated from dedifferentiated components is partially achievable using imaging and intraoperative findings. Given the complexity of these procedures, multidisciplinary collaboration and the anesthesiologist’s understanding of the surgical strategy are essential. This comprehensive overview highlights the technical depth and adaptability required for large RPS resections.

Retroperitoneal sarcomas (RPSs) often involve major vessels such as the iliac arteries/veins, inferior vena cava (IVC), and abdominal aorta, posing significant surgical challenges. Resection of RPSs involving large vessels requires advanced vascular techniques and multidisciplinary collaboration. In Part 3 of this series, technical strategies, pitfalls, and case-based insights for managing RPSs with large vessel involvement are described based on operative experience at a high-volume sarcoma center. Surgical approaches to iliac vessels, IVC resection with or without tumor thrombus, and aortic contact are described. Iliac vessel involvement may require in situ or staged vascular grafting. IVC resection with or without reconstruction is feasible in the presence of a thrombus or direct invasion, but the resection depends on hemodynamic tolerance and collateral circulation. Tumors with IVC thrombus extending into the right atrium require cardiopulmonary bypass. Preoperative arterial embolization and intraoperative ultrasound help minimize blood loss and guide resection margins. Dissection without aortic resection is often possible even when the tumor is close to the abdominal aorta. RPSs with vascular invasion can be safely resected using tailored strategies if the institution is prepared. Surgical expertise in retroperitoneal vascular anatomy and collaboration across specialties are essential to ensure safe and effective oncologic outcomes.

Tracheobronchial adenoid cystic carcinoma (ACC) is a rare malignant disease of the central airways. Complete resection is the primary goal for this tumor; however, it remains challenging due to the complexity of reconstruction, tumor submucosal spread, and the risk of dehiscence. Conversely, tracheobronchial ACC has relatively favorable long-term outcomes due to its indolent growth. Due to the rarity of this tumor, a clear treatment guideline has yet to be established. This study aimed to evaluate treatment strategies, perioperative outcomes, and long-term prognosis of tracheobronchial ACC cases at our institution to identify the optimal therapeutic strategy for this challenging disease. We retrospectively analyzed 11 patients who underwent surgical intervention for tracheobronchial ACC at our institution from 2000 to 2024. Clinical, surgical, and oncologic outcomes were assessed, including the impact of surgical margins and adjuvant therapy. Complete resection was achieved in two cases, while nine patients had positive margins requiring postoperative radiotherapy. No local recurrences were observed, but distant metastases occurred in 54.5% of cases. Oligometastatic disease was effectively managed with local therapy. The 5-year and 10-year overall survival rates were 90% and 75%, respectively. Surgical resection remains the cornerstone of treatment for tracheobronchial ACC, however achieving negative surgical margins is not always feasible. In such cases, postoperative radiotherapy is considered an effective strategy to mitigate the risk of local recurrence. Local treatment of oligometastatic disease may provide a survival. These results indicate the importance of a multimodal treatment approach tailored to the specific challenges of tracheobronchial ACC.

Partial-thickness rotator cuff tears (PTRCTs) are classified into intratendinous tears (ITT), bursal-side tears (BST), and articular-side tears (AST). ITT is relatively rare, and many aspects of its clinical presentation remain unknown. Moreover, there are few reports on arthroscopic rotator cuff repair (ARCR) of ITTs. To the best of our knowledge, few reports have compared the treatment outcomes of ARCR with those of BST, AST, and ITT. Patients who were diagnosed with ITT based on intraoperative findings and who could be followed up for at least 1 year postoperatively were included in this study. In all patients with PTRCTs, a complete tear was created and repaired via suture bridge techniques. Among the ITT, BST, and AST groups, the frequency of PTRCTs (ITT, BST, AST), patient background (age, sex, history of trauma), acromiohumeral distance (AHD), critical shoulder angle (CSA), lateral acromial angle (LAA), acromial morphology, Japanese Orthopaedic Association (JOA) score, and re-tear rate were compared. Fifteen patients underwent ARCR on ITT, 95 patients underwent BST, and 39 patients underwent AST. There were no significant differences in age, sex, or frequency of traumatic rotator cuff tears. The preoperative CSA showed significant differences; however, no significant differences were observed among the three groups for AHD, LAA, and acromion morphology. There were no significant differences in operation time, JOA score, or re-tear rate. The results of ARCR for ITT were good and may be a viable option for patients resistant to conservative treatment.

Japan has a higher prevalence of low birthweight infants (LBW, < 2500 g) than other developed countries. In this study, we aimed to clarify the descriptive epidemiological characteristics of LBW prevalence in Japan from 1980 to 2020. LBW prevalence data were obtained from the Vital Statistics of Japan. Trends in crude and age-standardized LBW prevalence rates for total and singleton births separately and rates for full-term births, as well as age-specific prevalence rates by maternal age at delivery, were analyzed using joinpoint regression. The crude LBW rate increased slowly from 5.18 per 100 births in 1980, rose sharply from the late 1980s, peaked at 9.62 in 2007, and then declined slowly to 9.22 in 2020 for the total births. The annual percent changes were 1.35% (1980–1987), 3.37% (1987–2000), 1.81% (2000–2006), and –0.24% (2006–2020), with an average annual percent change (APC) of 1.51%. Age-standardized rates for the singleton and full-term births showed a similar trend. Age-specific rates showed a sharp increase for approximately 10 years after 1985, followed by a decline in the group > 35 years of age. The rate for the 15–19 age group increased gradually, with no change point (APC = 0.60). These findings likely reflect changes in maternal and socio-environmental factors—such as increased maternal age, undernutrition, lower body mass index (BMI), and expanded use of assisted reproductive technology and perinatal care—and emphasize the importance of preconception care and maternal health care, including nutrition and life-course approaches, to reduce low birthweight risk.

Preventing osteoporosis in older populations is important for extending healthy life expectancy. Calcium is a crucial nutrient for maintaining bone health in this group. However, more than half of people aged ≥ 65 years have insufficient calcium intake. We investigated the influence of food store access on calcium intake in community-dwelling older adults. Our study employed a population-based cross-sectional design, using data from older adults aged 70–74 years living in three towns in northern Japan. Perceived food store access was assessed using a single question, while objective food store access was measured using a geographic information system. Dietary information was obtained using a brief-type self-administered diet history questionnaire. Insufficient calcium intake was defined as calcium consumption below the estimated average requirement for the participant’s age and sex. A log-binomial regression analysis was performed to determine the association between food store access and insufficient calcium intake. A total of 716 participants (mean age, 71.8 ± 1.4 years; 55.3% women) were included in this study. After adjusting for potential confounders, low objective food store access was associated with insufficient calcium intake (adjusted prevalence ratio for low vs high accessibility, 1.24; 95% confidence interval, 1.05–1.46). However, the perceived food store access was not associated with insufficient calcium intake. Our findings showed that low objective food store access is associated with insufficient calcium intake among independent older Japanese adults. Improving access to food stores may help prevent insufficient calcium intake in this population.

Patients with hematological malignancies frequently present with severe and intricate infections that pose life-threatening risks. Conventional pathogen detection methods offer limited clinical insights and therapeutic guidance. This retrospective study evaluated the clinical application of metagenomic next-generation sequencing (mNGS) in hematologic patients who remained febrile despite prolonged antibiotic therapy, which means unresponsive to antibiotic therapy. This retrospective analysis included 204 patients with hematologic malignancies, undergoing conventional pathogen detection and peripheral blood mNGS. The cohort was stratified into neutropenia and non-neutropenia groups to compare the diagnostic and therapeutic implications of mNGS versus conventional microbiological tests (CMT). Among the 204 patients with mNGS, the overall positive detection rate was significantly higher than that of CMT (68.1% vs 30.9%, P<0.001). In both the neutropenia and non-neutropenia group, mNGS demonstrated a higher positivity rate for bacteria than for CMT (bacteria, 36.4% vs 15.6%, P<0.01). mNGS proved notably advantageous for bloodstream infections with clinically relevant drug-resistant strains, particularly in the neutropenia cohort (26.4% vs 12.5%, P<0.001). Using a composite reference standard, mNGS manifested sensitivity and specificity rates of 78.4% and 61.9%, respectively. Patients in the neutropenia group derived superior clinical benefit from mNGS, including higher diagnostic accuracy and treatment efficacy (diagnosis, 56.4% vs 40.6%, P=0.036; treatment, 49.3% vs 31.3%, P = 0.016). Additionally, the 30-days mortality rate was notably higher among mNGS-positive patients who tested compared to those who tested negative (17.3% vs 1.5%, P<0.001). mNGS demonstrated clinical relevance in patients with hematologic malignancy who received prolonged antibiotic treatment and holds promise in predicting patient survival prognosis.

Oral contraceptive (OC)/low-dose estrogen progestin (LEP) affects both the coagulation and fibrinolytic systems and may cause alveolar osteitis (AO). However, whether OC/LEP discontinuation affects the incidence of AO has not been evaluated. The aim of this study was to investigate whether preoperative OC/LEP discontinuation influences the incidence of AO after wisdom tooth extraction in outpatients. A total of 130 women aged 18–47 years (median, 27 years) participated, and the total numbers of procedure days and teeth were 205 and 274, respectively. We compared the incidence of AOs between patients who discontinued OC/LEP before wisdom tooth extraction and those who did not. A total of 4/181 teeth (2.21%) in the discontinuation group and 7/93 (7.53%) in the continuation group exhibited AO, and Fisher’s exact test revealed a significant difference between the two groups (p=0.049). No serious adverse events, such as thrombosis, were observed. In conclusion, OC/LEP discontinuation was associated with a lower observed incidence of AO after third molar extraction.

As seen in the coronavirus pandemic, the social impact of the spread of emerging and re-emerging viral infections is significant. Whilst seasonal human coronaviruses with common cold symptoms have long been identified, there are only few studies on cellular entry pathway into host cells. Human coronavirus (HCoV)-229E, which has a positive single-stranded RNA genome, binds to the host cell surface receptor Aminopeptidase N and is taken up into the cell by endocytosis. The viral genome is then released from the endosome into the cytoplasm via uncoating step, the molecular mechanism of which remains unclear. In the uncoating of influenza A viruses, it is known that after membrane fusion in matured endosomes, unanchored ubiquitin chains present in the viral particle are exposed to the cytoplasmic side, which recruits the host factor histone deacetylase 6 (HDAC6) and promotes M1 uncoating. In this study, purified virus particles were used to investigate the involvement of ubiquitin in the uncoating of coronaviruses, and their properties were determined. The results show that there are few unanchored ubiquitin chains in coronavirus particles, suggesting that they use ubiquitin-independent uncoating different from influenza A virus. More interestingly, acidification within the endosome leads to nucleocapsid condensate formation in vitro. From these results, we would like to propose a new model that coronaviruses with long single-stranded RNA genomes efficiently uncoat their genomes by forming condensates during uncoating, thereby evading the innate immune response from the host. Understanding these molecular mechanisms is expected to lead to drug development.

Urinary trace metal elements are key biomarkers for assessing exposure to toxic metals, and are significant contributors to osteoporosis (OP). Epidemiological research examining the connection between adult bone mineral density (BMD) and trace metal elements exposure is still very scarce, nevertheless. The study aims to clarify the association between trace metal elements exposure and BMD. This cross-sectional study included 3,441 adults (aged 20 to 59) from 2011 to 2018 National Health and Nutrition Examination Survey (NHANES). Weighted multivariable logistic regression analysis, subgroup analysis, smoothing curve fitting and threshold effect analysis were conducted to explore the association between four urinary trace metal elements (barium, cesium, antimony, and tin) and BMD. We found that urinary cesium, antimony, and tin were positively associated with lumbar BMD, while urinary barium demonstrated an inverted U-shaped association in US adults. The results of this study are helpful for the development of strategies for bone mineral density management.

We report a case of a 50-year-old man referred to our department with a marked inflammatory response and severe renal dysfunction. Computed tomography scans revealed an inguinal bladder hernia with bilateral hydronephrosis. A urethral catheter was placed to relieve urinary retention, and antimicrobial therapy was initiated for pyelonephritis. Despite adequate urine output, renal function improved only partially, and hydronephrosis persisted. Further imaging and intraoperative findings confirmed that the hernia sac was adjacent to the bladder and the bilateral lower ureters, which were significantly stretched and displaced. Firm adhesions between the bladder and the hernia sac necessitated meticulous dissection to restore normal anatomy. Surgical repair of the inguinal hernia successfully repositioned the bladder. Although morphological upper urinary tract dilation persisted postoperatively, a mercaptoacetyltriglycine 3 renal scan demonstrated no evidence of functional obstruction, indicating improved ureteral patency. A urodynamic study (UDS) revealed significantly decreased bladder compliance, likely due to chronic displacement and compression within the scrotum, which impaired the detrusor function. The patient gradually regained spontaneous voiding after urethral catheter removal and initiation of clean intermittent catheterization. Follow-up UDS confirmed a substantial improvement in bladder compliance, indicating functional recovery. Follow-up imaging indicated the resolution of bilateral hydronephrosis and improvement of renal function. This case emphasizes the importance of recognizing lower ureteral entrapment in cases of bladder hernia and demonstrates that bladder dysfunction due to chronic displacement can be reversed by timely surgical intervention.

Chlorhexidine applied to the skin during catheter insertion can cause allergic reactions; however, its potential to cause perioperative anaphylaxis is often overlooked. Herein, we report a case of recurrent allergic reactions to unrecognized chlorhexidine exposure, leading to pulseless electrical activity. A 66-year-old man exhibited an allergic reaction during anesthesia induction for Y-graft replacement for an abdominal aortic aneurysm, and the planned surgery was aborted. Skin tests for anesthetics were negative. Two months later, he experienced itching after epidural catheter insertion but did not report it. During a second anesthesia induction, the patient experienced another allergic reaction of unknown etiology. Although hemodynamics stabilized after vasopressor administration, insertion of a central venous catheter 1 hour later to prevent further hypotension triggered pulseless electrical activity. Chlorhexidine was used as a skin disinfectant during catheter insertion before all four reactions and was confirmed to have caused the anaphylaxes using diagnostic tests. Chlorhexidine should be considered a potential cause of perioperative anaphylaxis.

We report a case of reconstruction for triple-negative metaplastic breast cancer that rapidly enlarged during neoadjuvant immunochemotherapy, requiring semi-emergency surgery. A 47-year-old female with metaplastic carcinoma (cT2N0M0, stage IIA) received pembrolizumab, paclitaxel, and carboplatin in a neoadjuvant fashion. Rapid tumor enlargement and axillary lymph node swelling occurred during the first cycle of immunochemotherapy, necessitating semi-emergency surgery to prevent tumor rupture (cT4bN1M0, stage IIIB). Right mastectomy with partial pectoralis major muscle resection and axillary lymph node dissection were performed, exposing the ribs and sternum. Reconstruction utilized an internal mammary artery perforator flap with caudal rotation-advancement, followed by meshed skin grafting. Despite partial epidermal necrosis, wound closure was achieved after 3 weeks. Chemotherapy resumed 4 weeks after surgery; radiation therapy was initiated 4.5 months later. The patient remains disease-free 18 months after surgery. To our knowledge, mastectomy with pectoralis major resection and internal mammary artery perforator flap reconstruction for a triple-negative metaplastic breast cancer that had rapidly progressed during neoadjuvant therapy has not been previously reported.

Atypical fibroxanthoma (AFX) is a rare tumor of uncertain histogenetic origin, generally seen in elderly patients’ chronically sun-damaged skin, most frequently in the head and neck region. Due to the absence of specific histopathologic features, AFX is a diagnosis of exclusion. Herein, we report clinical, histopathological, and molecular features of a young patient with a recurrent and giant AFX lesion on non-chronically sun-damaged skin. Histologically, the tumor was well-circumscribed, encapsulated, and dermal-based, composed of highly atypical and pleomorphic bizarre spindled cells with hyperchromatic and irregular nuclei and scarce multinucleated giant cells. There was no subcutaneous invasion, necrosis, or perineural/perivascular invasion. Tumoral cells were diffusely and strongly positive for CD10 but negative for melanocytic, cytokeratin, and muscle immunohistochemical markers. Almost five years after the excision, no recurrence and/or distant metastasis was observed. A pathogenic variant of a TP53 somatic mutation (c.375+1 G>A) was identified in the tumor.

Recent reforms in Japan’s medical education, particularly the revision of the Model Core Curriculum, have emphasized hands-on clinical training to improve student competencies. Despite growing awareness, implementation varies across institutions, and clinical education remains largely observational with limited procedural experience. In contrast, Germany’s medical education, rooted in practical training since the Meiji period influence, integrates structured clinical experience throughout the undergraduate curriculum, culminating in the sixth-year “Praktisches Jahr”. The present study compares undergraduate clinical training in obstetrics and gynecology (OB-GYN) between Japan and Germany, focusing on the author’s experience at the University Hospital of Düsseldorf and Nagoya University Hospital. The OB-GYN training program at Düsseldorf emphasizes direct patient care, clinical reasoning, and active learning through the Mini-Clinical Evaluation Exercise, problem-based learning, and simulation-based ultrasound practice. Educator involvement is institutionalized, and dual-feedback systems enhance accountability. The Nagoya program focuses on simulations and observations, with structured learning in professionalism, basic procedures, and journal clubs, but lacks consistent feedback mechanisms and opportunities for independent clinical reasoning. Therefore, Japan may enhance its undergraduate clinical education by incorporating Germany’s practical training approaches, including structured inpatient case assignments, bidirectional feedback systems, and the greater integration of clinical decision-making. These insights support curriculum reforms that foster student engagement and professional competence. Future efforts need to align these adaptations with Japan’s unique educational and institutional contexts to ensure sustainable improvements in medical education.