Search Results (359)

Hypothermia-related deaths present significant diagnostic challenges due to non-specific and often inconsistent autopsy findings. This study investigated the histological and immunohistochemical alterations associated with primary and secondary hypothermia in an experimental Rattus norvegicus model, focusing on the effects of benzodiazepine and alcohol ingestion. Twenty-one male rats were divided into three groups: control (K), benzodiazepine-treated (B), and alcohol-treated (A). After two weeks of substance administration, hypothermia was induced and multiple organ samples were analyzed. Histologically, renal tissue showed hydropic and vacuolar degeneration, congestion, and acute tubular injury across all groups, with no significant differences in E-cadherin expression. Lung samples revealed congestion, emphysema, and hemorrhage, with more pronounced vascular congestion in the alcohol and benzodiazepine groups. Cardiac tissue exhibited vacuolar degeneration and protein denaturation, particularly in substance-exposed animals. The spleen showed preserved architecture but increased erythrocyte infiltration and significantly elevated myeloperoxidase (MPO)-positive granulocytes in the intoxicated groups. Liver samples demonstrated congestion, focal necrosis, and subcapsular hemorrhage, especially in the alcohol group. Immunohistochemical analysis revealed statistically significant differences in MPO expression in both lung and spleen tissues, with the highest levels observed in the benzodiazepine group. Similarly, CK7 and CK20 expression in the gastroesophageal junction was significantly elevated in both alcohol- and benzodiazepine-treated animals compared to the controls. In contrast, E-cadherin expression in the kidney did not differ significantly among the groups. These findings suggest that specific histological and immunohistochemical patterns, particularly involving pulmonary, cardiac, hepatic, and splenic tissues, may help differentiate primary hypothermia from substance-related secondary hypothermia. The study underscores the value of integrating toxicological, histological, and molecular analyses to enhance the forensic assessment of hypothermia-related fatalities. Future research should aim to validate these markers in human autopsy series and explore additional molecular indicators to refine diagnostic accuracy in forensic pathology. Full article

Fat embolism is a critical medical emergency often resulting from long bone fractures or amputations, leading to acute respiratory distress syndrome (ARDS). The NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome, a key regulator of innate immunity, is activated by reactive oxygen species and tissue damage, contributing to inflammatory responses. This study examines the role of NLRP3 in fat embolism-induced ARDS and evaluates the therapeutic potential of MCC950, a selective NLRP3 antagonist. Fat embolism was induced by fatty micelle injection into the tail vein of Sprague Dawley rats. Pulmonary injury was assessed through lung weight gain as an edema indicator, NLRP3 expression via Western blot, and IL-1β levels using ELISA. Histological damage and macrophage infiltration were evaluated with hematoxylin and eosin staining. Fat embolism significantly increased pulmonary NLRP3 expression, lipid peroxidation, IL-1β release, and macrophage infiltration within four hours, accompanied by severe pulmonary edema. NLRP3 was localized in type I alveolar cells, co-localizing with aquaporin 5. Administration of MCC950 significantly reduced inflammatory responses, lipid peroxidation, pulmonary edema, and histological damage, while attenuating MAPK cascade phosphorylation of ERK and Raf. These findings suggest that NLRP3 plays a critical role in fat embolism-induced acute respiratory distress syndrome, and its inhibition by MCC950 may offer a promising therapeutic approach. Full article

Background/Objective: The COVID-19 pandemic profoundly transformed social life worldwide, indiscriminately affecting individuals across all age groups. Children have not been exempted from the risk of severe illness and death caused by COVID-19. Objective: This paper sought to describe the clinical findings, laboratory and imaging results, and hospital care provided for severe and critical cases of COVID-19 in unvaccinated children, with or without severe asthma, hospitalized in a public referral service for COVID-19 treatment in the Brazilian state of Pernambuco. Methods: This was a case series study of severe and critical COVID-19 in hospitalized, unvaccinated children, with or without severe asthma, conducted in a public referral hospital between March 2020 and June 2021. Results: The case series included 80 children, aged from 1 month to 11 years, with the highest frequency among those under 2 years old (58.8%) and a predominance of males (65%). Respiratory diseases, including severe asthma, were present in 73.8% of the cases. Pediatric multisystem inflammatory syndrome occurred in 15% of the children, some of whom presented with cardiac involvement. Oxygen therapy was required in 65% of the cases, mechanical ventilation in 15%, and 33.7% of the children required intensive care in a pediatric intensive care unit. Pulmonary infiltrates and ground-glass opacities were common findings on chest X-rays and CT scans; inflammatory markers were elevated, and the most commonly used medications were antibiotics, bronchodilators, and corticosteroids. Conclusions: This case series has identified key characteristics of children with severe and critical COVID-19 during a period when vaccines were not yet available in Brazil for the study age group. However, the persistence of low vaccination coverage, largely due to parental vaccine hesitancy, continues to leave children vulnerable to potentially severe illness from COVID-19. These findings may inform the development of public health emergency contingency plans, as well as clinical protocols and care pathways, which can guide decision-making in pediatric care and ensure appropriate clinical management, ultimately improving the quality of care provided. Full article

Background: Patients with mastocytosis may present with exacerbated respiratory symptoms and lung diseases resulting from mast cell mediator release. However, their prevalence and severity level remain under debate. The study aims to analyze the prevalence of respiratory symptoms and the usefulness of lung function tests like spirometry, diffusing capacity of the lung for carbon monoxide (DLCO), and high-resolution computed tomography (HRCT) of the chest in mastocytosis patients presenting with dyspnea, cough, and exercise intolerance. Methods: We included 104 patients with mastocytosis and 71 healthy controls. Data collection encompassed patient interview, clinical examination, spirometry, DLCO, and chest HRCT. Diagnosis of mastocytosis included bone marrow biopsies and serum tryptase measurements. Results: Compared to controls, patients with mastocytosis exhibited significantly lower values in FEV1/VC ratio, absolute DLCO/VA, predicted DLCO/VA, absolute DLCOcSB, and predicted DLCOcSB (p < 0.001). Commonly reported respiratory symptoms included dyspnea (36.5%), chest tightness (22.1%), and wheezing (9.6%). Airway obstruction was identified in 7.7% of patients; however, it appeared to be independent of the mastocytosis subtype. A decreased DLCO/VA ratio was observed in 4.8% of patients, but HRCT did not reveal any evidence of underlying lung disease. Conclusions: Mastocytosis appears to be a risk factor for the occurrence and exacerbation of respiratory symptoms. However, airway obstruction and impairment of the alveolar–capillary membrane seem to occur independently of the clinical subtype of mastocytosis. Additionally, the causal relationship between pulmonary involvement, mast cell infiltration of the alveolar–capillary membrane, and the systemic circulation of mast cell mediators remains unclear and requires further research. Full article

Increased epithelial and endothelial permeability, along with dysregulated inflammatory responses, are key aspects of acute respiratory distress syndrome (ARDS) pathophysiology, which not only impact the lungs but also contribute to detrimental organ crosstalk with distant organs, ultimately leading to multiple organ dysfunction syndrome (MODS)—the primary cause of morbidity and mortality in patients with lung injury (LI) and ARDS. It is predominantly manifested by hypoxemic respiratory failure and bilateral pulmonary infiltrates, which cannot be fully attributed to cardiac failure or hypervolemia, but rather to alveolo-capillary barrier dysfunction, dysregulated systemic and pulmonary inflammation, immune system abnormalities, and mechanical stimuli-related responses. However, these pathological features are not uniform among patients with ARDS, as distinct subphenotypes with unique biological, clinical, physiological, and radiographic characteristics have been increasingly recognized in recent decades. The severity of ARDS, clinical outcomes, mortality, and efficacy of applied therapeutic measures appear significant depending on the respective phenotype. Acknowledging the heterogeneity of ARDS and defining distinct subphenotypes could significantly modify therapeutic strategies, enabling more precise and targeted treatments. To address these issues, a comprehensive literature search was conducted in PubMed using predefined keywords related to ARDS pathophysiology, subphenotypes, and personalized therapeutic approaches. Optimizing the identification and characterization of discrete ARDS subphenotypes—based on clinical, biological, physiological, and radiographic criteria—will deepen our understanding of ARDS pathophysiology, promote targeted recruitment in prospective clinical studies to define patient clusters with heterogeneous therapeutic responses, and support the shift toward individualized treatment strategies. Full article

Introduction: Pertussis, a vaccine-preventable disease caused by Bordetella pertussis, is resurging globally due to declining immunization rates. This study explores the clinical and epidemiological features of pediatric pertussis cases in a regional Romanian hospital amid growing vaccine hesitancy. Methods: We conducted a retrospective cohort study on 99 children diagnosed with pertussis and admitted to Ploiești Pediatric Hospital between January 2024 and January 2025. Demographic, clinical, laboratory, and radiological data were analyzed using SPSS 25.0. Results: The median age was 11 months (IQR 4–25), with 12.1% under two months, and ineligible for the first DTaP dose. Notably, 72.7% of children were unvaccinated; 59.4% had missed scheduled doses. None of the mothers received the DTaP vaccination during pregnancy. Most cases (55.6%) had bilaterally accentuated interstitial patterns on chest X-ray, significantly associated with vaccination status (p = 0.019). The leukocyte count was higher in children with alveolar infiltrates (p = 0.028), and as the number of vaccine doses increased, the leukocyte count tended to slightly decrease (p = 0.022, R = −0.229). PCR confirmation was obtained after a mean of 2.2 days, with 12.1% of cases confirmed post-discharge. Azithromycin was used in 74.7% of cases, with good tolerability. Conclusions: Low pediatric and maternal vaccine uptake was a major contributor to pertussis resurgence in this cohort. Radiological severity correlated with vaccination status, suggesting that vaccination may confer protection not only against infection but also against severe pulmonary involvement. These findings support urgent public health efforts to restore vaccine confidence and coverage, particularly among vulnerable infant populations and expectant mothers. Full article

Platelet-rich plasma (PRP) has become an increasingly valuable biologic approach for personalized regenerative medicine because of its potent anti-inflammatory/healing effects. It is thought to be an excellent source of growth factors that can promote tissue healing and lessen fibrosis. Although this treatment has demonstrated effectiveness in numerous disease areas, its impact on pulmonary fibrosis (PF) caused by silver nanoparticles (AgNPs) via its antiapoptotic effects remains to be explored. AgNPs were synthesized biologically by Bacillus megaterium ATCC 55000. AgNP characterization was carried out via UV–Vis spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) imaging to reveal monodispersed spheres with a mean diameter of 45.17 nm. A total of 48 male Wistar rats divided into six groups, with 8 rats per group, were used in the current study on the basis of sample size and power. The groups used were the PRP donor, control, AgNP, AgNP + PRP, AgNP + dexamethasone (Dexa) rat groups, and a recovery group. Body weights, hydroxyproline (HP) levels, and CASP3 and TWIST1 gene expression levels were assessed. H&E and Sirius Red staining were performed. Immunohistochemical studies for inducible nitric oxide synthase (iNOS) and cluster of differentiation 68 (CD68) with histomorphometry were conducted. A significant reduction in body weight (BWt) was noted in the AgNP group compared with the AgNP + PRP group (p < 0.001). HP, CASP3, and TWIST1 expression levels were significantly increased by AgNPs but decreased upon PRP (p < 0.001) treatment. Compared with those in the control group, the adverse effects of AgNPs included PF, lung alveolar collapse, thickening of the interalveolar septa, widespread lymphocytic infiltration, increased alveolar macrophage CD68 expression, and iNOS positivity in the cells lining the alveoli. This work revealed that PRP treatment markedly improved the histopathological and immunohistochemical findings observed in the AgNP group in a manner comparable to that of the Dexa. In conclusion, these results demonstrated the therapeutic potential of PRP in a PF rat model induced via AgNPs. This study revealed that PRP treatment significantly improved the histopathological and immunohistochemical alterations observed in the AgNP-induced group, with effects comparable to those of the Dexa. In conclusion, these findings highlight the therapeutic potential of PRP in a rat model of AgNP-induced PF. Full article

Primary graft dysfunction (PGD) remains a major complication after lung transplantation. Donor lung ischemia followed by reperfusion drives oxidative stress and inflammatory responses. The pathophysiology is influenced by various donor-, procedure-, and recipient-related factors, which complicates the identification of biomarkers for evaluation of donor lung injury or therapeutic interventions to minimize PGD. This review provides an overview of the molecular pathways that contribute to PGD pathophysiology, including those involved in loss of endothelial–epithelial membrane integrity, neutrophil infiltration, and the development of pulmonary edema. Full article

Background: Diabetic lung disease, characterized by inflammation and fibrosis, is an emerging chronic complication of type 2 diabetes mellitus (T2DM). However, systematic studies on the effects of exercise interventions remain limited. This study aimed to investigate the impact of different exercise types (swimming, resistance training, and high-intensity interval training [HIIT]) on pulmonary inflammation and fibrosis in T2DM mice, and to explore underlying molecular mechanisms. Methods: A T2DM mouse model was established by a high-fat diet (HFD) combined with streptozotocin (STZ) induction. Mice were randomly divided into sedentary control, swimming, resistance training, and HIIT groups, and underwent 8 weeks of exercise intervention. After the intervention, body composition was assessed. Lung histopathological changes were evaluated by hematoxylin&eosin (HE) and Masson staining. Inflammatory cytokines, fibrosis markers, and the expression of the TGF-β1/Smad signaling pathway were detected. Macrophage infiltration and polarization were also analyzed. Results: Exercise intervention improved body composition and reduced oxidative stress in T2DM mice. All three exercise modalities downregulated inflammatory cytokine expression, inhibited macrophage activation and M1 polarization, and promoted M2 polarization. Additionally, exercise improved lung tissue structure, reduced collagen deposition, and decreased the expression of fibrosis-related markers. Furthermore, anti-fibrotic effects were mediated by suppression of the TGF-β1/Smad signaling pathway and inhibition of epithelial-mesenchymal transition (EMT). Among the interventions, HIIT demonstrated the strongest inhibitory effect on the TGF-β1/Smad pathway, while swimming showed the most significant anti-inflammatory benefits. Conclusions: Different types of exercise effectively alleviate pulmonary inflammation and fibrosis in T2DM mice. These effects are closely related to the inhibition of oxidative stress, regulation of macrophage polarization, and suppression of TGF-β1/Smad signaling activation, with swimming and HIIT demonstrating superior protective benefits. Full article

Background/Objectives: Pulmonary lymphangitic carcinomatosis (PLC) is a rare, aggressive manifestation of metastatic cancer characterized by lymphatic infiltration of the lungs, typically indicating advanced disease and poor prognosis. Methods: This comprehensive narrative review evaluates the role of [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomography (PET) imaging in assessing PLC. Results: Current evidence demonstrates that [18F]FDG PET/CT achieves high diagnostic accuracy, with sensitivity and specificity ranging from 86 to 97% and 84 to 100%, respectively, particularly when employing semiquantitative metrics such as peritumoral standardized uptake value (SUVmax) thresholds (e.g., ≥2.1). PET/CT surpasses high-resolution computed tomography (HRCT) in distinguishing PLC from mimics like pulmonary sarcoidosis by identifying distinct metabolic patterns: bronchovascular hypermetabolism in PLC versus subpleural nodular uptake in sarcoidosis. Prognostically, metabolic tumor burden (e.g., SUVmax × involved lobes) and novel cPLC classifications (localized to the ipsilateral or contralateral lung) independently predict progression-free survival. However, challenges persist, including non-specific tracer uptake in inflammatory conditions and variability in SUV measurements due to technical factors. Emerging digital PET/CT systems, with enhanced spatial resolution, may improve the detection of focal PLC and reduce false negatives. While [18F]FDG PET/CT is invaluable for whole-body staging, therapeutic monitoring and biopsy guidance, the standardization of protocols and multicenter validation of prognostic models are critical for clinical integration. Future research should explore novel tracers (e.g., PSMA for prostate cancer-related PLC) and machine learning approaches to refine diagnostic and prognostic accuracy. Conclusions: This review underscores the role and the transformative potential of [18F]FDG PET/CT in PLC management while advocating for rigorous standardization to maximize its clinical utility. Full article

Background and Objectives: Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease with limited therapeutic options. Current therapies (pirfenidone, nintedanib) exhibit modest efficacy and significant side effects, underscoring the need for novel strategies targeting early pathogenic drivers. Saroglitazar (SGZ), a dual PPARα/γ agonist with anti-inflammatory properties approved for diabetic dyslipidemia, has not been explored for IPF. We aimed to investigate SGZ’s therapeutic potential in pulmonary fibrosis and elucidate its mechanisms of action. Materials and Methods: Using a bleomycin (BLM)-induced murine pulmonary fibrosis model, we administered SGZ therapeutically. A histopathological assessment (H&E, Masson’s trichrome, collagen I immunofluorescence), Western blotting, and qRT-PCR analyzed the fibrosis progression and inflammatory markers. Flow cytometry evaluated the macrophage polarization. In vitro studies used RAW264.7 macrophages stimulated with BLM/LPS and MRC-5 fibroblast co-cultures. The NF-κB/NLRP3 pathway activation was assessed through protein and gene expression. Results: SGZ significantly attenuated BLM-induced histopathological hallmarks, including alveolar wall thickening, collagen deposition, and inflammatory infiltration. Fibrotic markers (OPN, α-SMA) and pro-inflammatory cytokines (IL-1β, TNF-α, IL-6) were downregulated in the SGZ-treated mice. Mechanistically, SGZ suppressed the M1 macrophage polarization (reduced CD86⁺ populations) and inhibited the NF-κB/NLRP3 pathway activation in the alveolar macrophages. In the RAW264.7 cells, SGZ decreased the NLRP3 inflammasome components (ASC, cleaved IL-1β) and cytokine secretion. Co-cultures demonstrated that the SGZ-treated macrophage supernatants suppressed the fibroblast activation (α-SMA, collagen I) in MRC-5 cells. Conclusions: SGZ attenuates pulmonary fibrosis by suppressing macrophage-driven inflammation via NF-κB/NLRP3 inhibition and disrupting the macrophage–fibroblast crosstalk. These findings nominate SGZ as a promising candidate for preclinical optimization and future clinical evaluation in IPF. Full article

Since the COVID-19 pandemic, the utilization of transthoracic ultrasonography (TTU) in the evaluation of pulmonary field artefacts has become standard practice among clinicians. However, there is a considerable lack of knowledge regarding the assessment of diaphragm mobility in the context of various lung diseases. Although numerous conditions are known to affect diaphragm mobility, including neurological, cardiovascular, and infectious diseases, it appears that pulmonary diseases may also limit the mobility of this major respiratory muscle. Despite the evidence of diaphragm mobility disorders in patients diagnosed with lung cancer, there is a discrepancy in the literature regarding the function of the diaphragm in individuals with chronic obstructive pulmonary disease (COPD). A shared aetiological factor frequently results in the co-occurrence of the aforementioned diseases. It is, however, possible to detect patients whose obstructive airway disease is caused only by the compression of infiltrative and nodal lesions rather than COPD. Bilateral TTU of diaphragmatic mobility in correlation with other available pulmonary function tests and radiological imaging may prove to be a valuable approach to isolating lung cancer patients with COPD overdiagnosis. Conversely, the overdiagnosis of COPD has been implicated in the potentially unnecessary and harmful use of inhaled medications with their adverse effects (e.g., cardiac arrhythmias, limb tremor, cough, and pneumonia), the failure to decrease obstruction in cases of other lung disorders, and the potential to contribute to the delayed diagnosis of the underlying condition responsible for the respiratory symptoms. This paper aims to provide a comprehensive overview of the utilization of ultrasound in the evaluation of diaphragm movement impairments for the detection of obstructions while also delineating the underlying limitations of this technique. Moreover, we propose a diagnostic algorithm for the purpose of excluding unilateral obstruction resulting from infiltrative neoplastic masses based on the ultrasound assessment of diaphragmatic mobility. Full article

Background/Objectives: In preclinical research of airway inflammation, the endotoxin (lipopolysaccharide: LPS)–induced acute interstitial pneumonitis is the most commonly used mechanism model. However, studies apply different LPS serotypes, doses, administration routes, and reference compounds, making result interpretation challenging and drawing conclusions difficult. Therefore, here we aimed to optimize, characterize, and validate this model with dexamethasone in mice. Methods: Pneumonitis was induced by intratracheal LPS (0.25, 1, 2.5, 5 mg/kg; E. coli O111:B4) in C57BL/6J and NMRI mice; controls received phosphate-buffered saline (PBS). Dexamethasone (5 mg/kg i.p.) was used as a positive control. Respiratory functions were measured by restrained plethysmography 24 h after induction, and core body temperature was monitored. Lungs were excised and weighed, and then myeloperoxidase (MPO) activity and histopathological analysis were performed to assess pulmonary inflammation. Results: LPS-induced significant body weight loss, perivascular pulmonary edema, MPO activity increase, neutrophil infiltration, and respiratory function impairment in a dose-independent manner. However, LPS-induced hypothermia dynamics and duration were dose-dependent. The inhibitory effects of the reference compound dexamethasone were only detectable in the case of the 0.25 mg/kg LPS dose on most inflammatory parameters. These results did not differ substantially between C57BL/6J and NMRI mouse strains. Conclusions: Very low doses of LPS induce characteristic functional and morphological inflammatory alterations in the lung, which do not worsen in response to even 20 times higher doses. Since the effect of pharmacological interventions is likely to be detectable in the case of the 0.25 mg/kg LPS dose, we suggest this protocol for testing novel anti-inflammatory agents. Full article

Background: Influenza B usually causes mild illness in children. Severe and fatal cases can occur when complicated by secondary Staphylococcus aureus (S. aureus) pneumonia, including community-acquired methicillin-resistant Staphylococcus aureus (MRSA). We present a rare, rapidly progressive fatal case in an adolescent with no known medical history to highlight diagnostic and therapeutic pitfalls. Case Presentation: A 16-year-old boy with no known underlying conditions (unvaccinated for influenza) presented critically ill at “Sf. Ioan” Clinical Emergency Pediatric Hospital in Galați after one week of high fever and cough. He was in respiratory failure with septic shock, requiring immediate intubation and vasopressors. Chest X-ray (CXR) showed diffuse bilateral infiltrates (acute respiratory distress syndrome, ARDS). Initial laboratory tests revealed leukopenia, severe thrombocytopenia, disseminated intravascular coagulation (DIC), rhabdomyolysis, and acute kidney injury (AKI). Reverse transcription polymerase chain reaction (RT-PCR) confirmed influenza B, and blood cultures grew MRSA. Despite maximal intensive care, including mechanical ventilation, antibiotics (escalated for MRSA), antiviral therapy, and cytokine hemoadsorption therapy, the patient developed refractory multi-organ failure and died on hospital day 6. Autopsy revealed bilateral necrotizing pneumonia (NP) without radiographic cavitation, underscoring the diagnostic challenge. Discussion: The initial chest radiography showed diffuse bilateral pulmonary infiltrates, predominantly in the lower zones, with an ill-defined, patchy, and confluent appearance. Such appearance, in our case, was more suggestive of rapid progressive NP caused by MRSA rather than the typical pneumococcal one. This is one of the few reported cases of influenza B–MRSA coinfection with fulminant rhabdomyolysis and autopsy-confirmed necrosis. Our fulminant case illustrates the synergistic virulence of influenza and MRSA. Toxin-producing MRSA strains can cause NP and a “cytokine storm,” causing capillary leak, ARDS, shock, and DIC. Once multi-organ failure ensues, the prognosis is grim despite aggressive care. The absence of early radiographic necrosis and delayed anti-MRSA therapy (initiated after culture results) likely contributed to the poor outcome. Conclusions: Influenza B–MRSA co-infection, though rare, demands urgent empiric anti-MRSA therapy in severe influenza cases with leukopenia or shock, even without radiographic necrosis. This fatal outcome underscores the dual imperative of influenza vaccination and early, aggressive dual-pathogen targeting in high-risk presentations. Full article

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the coronavirus disease 2019 (COVID-19) pandemic that devastated the world. While this is a respiratory virus, one feature of the SARS-CoV-2 infection was recognized to cause pathogenesis of other organs. Because the membrane fusion protein of SARS-CoV-2, the spike protein, binds to its major host cell receptor angiotensin-converting enzyme 2 (ACE2), which regulates a critical mediator of cardiovascular diseases, angiotensin II, COVID-19 is largely associated with vascular pathologies. The present study examined the pulmonary vasculature of COVID-19 patients using large sample sizes and provides mechanistic information through histological observations. We studied 56 postmortal lung samples from COVID-19 patients. The comparative group consisted of 17 postmortal lung samples from patients who died of influenza A virus subtype H1N1. The examination of 56 autopsy lung samples showed thickened vascular walls of small pulmonary arteries after 14 days of disease compared to H1N1 influenza patients who died before the COVID-19 pandemic started. Pulmonary vascular remodeling in COVID-19 patients was associated with hypertrophy of the smooth muscle layer, perivascular fibrosis, edema and lymphostasis, inflammatory infiltration, perivascular hemosiderosis, and neoangiogenesis. We found a correlation between the duration of hospital stay and the thickness of the muscular layer of the pulmonary arterial walls. These results demonstrate that COVID-19 significantly affected the pulmonary vasculature in fatal-course patients, also suggesting the need for careful follow-up in non-fatal cases, at risk of pulmonary hypertension. Full article