Pathology of Idiopathic Interstitial Pneumonias

Challenges in recognizing airway-centered fibrosis: Observer concordance and its role in fibrotic hypersensitivity pneumonitis

BACKGROUND

The interobserver agreement regarding airway-centered fibrosis (ACF), the key diagnostic feature of fibrotic hypersensitivity pneumonitis (fHP) has not been sufficiently addressed to date. We applied digital image analysis to investigate this issue and extracted histological features of ACF to correlate with fHP diagnosis.

METHODS

A total of 111 selected glass slides from 17 fHP and 30 idiopathic pulmonary fibrosis (IPF) were scanned and seven expert pulmonary pathologists were tasked with digital annotation of ACF. Interobserver agreement on annotated ACF was assessed using Fleiss' kappa value. ACF recognized by majority of pathologists (4 or more) were considered as consensus ACF (cACF), and their frequencies were compared between fHP and IPF cases.

RESULTS

Fleiss' kappa agreement in ACF recognition was 0.32 among seven pathologists. A significant difference between cryobiopsy and VATS specimens regarding an average ACF count per slide (p = 0.012) was found. The number of cACFs in a single case ranged from 0 to 20 (mean 5.71) for fHP cases and 0 to 13 (mean 1.80) for IPF cases (p = 0.011). When limited to surgical biopsies, the average number of cACF was 10.3 for fHP vs. 1.68 for IPF (p < 0.001). The common characteristic features of cACF in fHP were their confinement to the vicinity of respiratory bronchioles, frequent association with peribronchiolar metaplasia, and mild to moderate lymphocytic infiltration.

CONCLUSIONS

The recognition of ACF varies widely among pathologists. We identified common histologic features of ACF in fHP cases, proposing criteria for ACF recognition in fHP.

Integrated multi-omics profiling landscape of organising pneumonia

BACKGROUND

Organising pneumonia (OP) is one of the most common and lethal diseases in the category of interstitial pneumonia, along with lung cancer. Reprogramming of lipid metabolism is a newly recognized hallmark of many diseases including cancer, cardiovascular disorders, as well as liver fibrosis and sclerosis. Increased levels of ceramides composed of sphingosine and fatty acid, are implicated in the development of both acute and chronic lung diseases. However, their pathophysiological significance in OP is unclear. The aim of this study was to investigate the role of lipid metabolism reprogramming in OP, focusing on inflammation and fibrosis.

METHODS

Comprehensive multi-omics profiling approaches, including single-cell RNA sequencing, Visium CytAssist spatial transcriptomics, proteomics, metabolomics and mass spectrometry, were employed to analyze the tissues. OP mice model was utilized and molecular mechanisms were investigated in macrophages.

RESULTS

The results revealed a significant association between OP and lipid metabolism reprogramming, characterized by an abnormal expression of several genes related to lipid metabolism, including CD36, SCD1, and CES1 mainly in macrophages. CD36 deficiency in alveolar macrophages, led to an increased expression of C16/24 ceramides that accumulated in mitochondria, resulting in mitophagy or mitochondrial dysfunction. The number of alveolar macrophages in OP was significantly reduced, which was probably due to the ferroptosis signaling pathway involving GSH/SLC3A2/GPX4 through CD36 downregulation in OP. Furthermore, macrophage secretion of DPP7 and FABP4 influenced epithelial cell fibrosis.

CONCLUSIONS

CD36 inhibited the ferroptosis pathway involving SLC3A2/GPX4 in alveolar macrophages of OP tissue by regulating lipid metabolism, thus representing a new anti-ferroptosis and anti-fibrosis effect of CD36 mediated, at least in part, by ceramides.

HIGHLIGHTS

Our findings reveal a significant association between organising pneumonia and lipid metabolism reprogramming and will make a substantial contribution to the understanding of the mechanism of organising pneumonia in patients.

Multidisciplinary Approach to the Diagnosis of Idiopathic Interstitial Pneumonias: Focus on the Pathologist's Key Role

Idiopathic Interstitial Pneumonias (IIPs) are a heterogeneous group of the broader category of Interstitial Lung Diseases (ILDs), pathologically characterized by the distortion of lung parenchyma by interstitial inflammation and/or fibrosis. The American Thoracic Society (ATS)/European Respiratory Society (ERS) international multidisciplinary consensus classification of the IIPs was published in 2002 and then updated in 2013, with the authors emphasizing the need for a multidisciplinary approach to the diagnosis of IIPs. The histological evaluation of IIPs is challenging, and different types of IIPs are classically associated with specific histopathological patterns. However, morphological overlaps can be observed, and the same histopathological features can be seen in totally different clinical settings. Therefore, the pathologist's aim is to recognize the pathologic-morphologic pattern of disease in this clinical setting, and only after multi-disciplinary evaluation, if there is concordance between clinical and radiological findings, a definitive diagnosis of specific IIP can be established, allowing the optimal clinical-therapeutic management of the patient.

Acute exacerbation of idiopathic pulmonary fibrosis after bivalent {tozinameran and famtozinameran} mRNA COVID-19 vaccination

An 82-year-old man diagnosed with interstitial lung disease through computed tomography (CT) 1 year prior received a bivalent (tozinameran and famtozinameran) mRNA COVID-19 vaccine. He developed respiratory symptoms 1.5 months later, and chest high-resolution CT revealed new ground-glass opacities showing traction bronchiectasis. Transbronchial lung cryobiopsy revealed organizing acute lung injury and fibrosis with architectural destruction. The patient was diagnosed with an acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF). The bivalent mRNA COVID-19 vaccination was determined as the cause of the AE-IPF based on detailed medical history and examination findings. High-dose corticosteroid therapy improved the patient's symptoms and radiological findings.

Case report: Idiopathic pulmonary fibrosis induced by nab-paclitaxel: A rare complication

Background: Ovarian cancer is one of the deadliest gynecological cancers, with the most advanced disease and poor survival. Although BRCA genes play a key role in maintaining genomic stability and providing the possibility of clinically individualized treatments, with the emergence of new and more appropriate treatment options, new treatment-related adverse events are challenging and difficult for clinicians. Case presentation: An 80-year-old Chinese woman was diagnosed with stage IIIC ovarian high-grade serous adenocarcinoma (CT3cN1MX) with BRCA2 as the causative gene. She underwent three courses of neoadjuvant chemotherapy with nab-paclitaxel 400 mg and carboplatin 450 mg before surgery. Chest HRCT prior to chemotherapy demonstrated bilateral interstitial pneumonia. During chemotherapy, there were four episodes of dry cough, shortness of breath, dyspnea, and three episodes of bone marrow suppression. The symptoms became intermittent and progressively worse, and after three sessions of empirical cough and phlegm relief, oxygen inhalation, corticosteroids, anti-infectives, and leukopenia therapy, the symptoms became intermittent and progressively worse. The diagnosis of idiopathic pulmonary fibrosis came a week after the third round of chemotherapy. After a strong dose of corticosteroids and nintedanib anti-fibrosis therapy, the pulmonary symptoms abated, and intermediate tumor starvation was performed. The combination therapy was subsequently discontinued, and the patient experienced significant relief from pulmonary symptoms. Treatment response was positive following single-agent nab-paclitaxel 400 mg chemotherapy in combination with nintedanib 150 mg anti-fibrosis therapy. Conclusion: In this report, we describe a rare case of idiopathic pulmonary fibrosis associated with the use of nab-paclitaxel and carboplatin in ovarian cancer. During treatment, it is necessary to maintain a high level of vigilance for patients with interstitial pneumonia and engage the attention of clinicians to improve medication safety. Early diagnosis and anti-fibrosis therapy can reverse lung damage.

Exploring the Value of Features of Lung Texture in Distinguishing Between Usual and Nonspecific Interstitial Pneumonia

RATIONALE AND OBJECTIVES

This article aims to explore the potential use of lung texture assessed in CT images in distinguishing between the usual interstitial pneumonia and the nonspecific interstitial pneumonia.

MATERIALS AND METHODS

A retrospective analysis of 96 cases of interstitial pneumonia was performed. Among these cases, there were 40 cases of usual interstitial pneumonia (UIP) and 56 cases of the nonspecific interstitial pneumonia (NSIP) . All of the patients underwent computed tomography (CT) scans. A lung intelligence kit (LK) was utilized to perform lung segmentation and texture feature extraction. The significant variables were determined by variance analysis, least absolute shrinkage and selection operator (LASSO) and multivariate logistic regression. Finally, a multivariate logistic regression model was established to distinguish between the two types of interstitial pneumonia. Receiver operating characteristic (ROC) curves, area under the curve (AUC) values, sensitivity, and specificity were used to evaluate the performance of the established model.

RESULTS

A total of 100 texture features were extracted from the whole lung that was segmented by LK, and 8 features remained after feature reduction. The AUC, sensitivity, and specificity of the multivariate logistic regression model in the training group and the test group were 0.952 and 0.838, 0.821 and 0.667, and 0.949 and 0.824, respectively.

CONCLUSION

It is possible to distinguish between UIP and NSIP using lung texture features obtained from CT images.

Interobserver agreement of interstitial lung fibrosis Reporting and Data System (ILF-RADS) at high-resolution CT

PURPOSE

To assess the interobserver agreement of interstitial lung fibrosis Reporting and Data System (ILF-RADS) in interpretation and categorization of interstitial lung disease (ILD) at high-resolution CT (HRCT).

METHODS

Retrospective analysis was performed on 65 consecutive patients (36 male and 29 female), median age 53 years, who were referred to the Radiology Department, Mansoura University, in the period from July 2016 to February 2020. They were expected clinically to have diffuse lung disease and underwent HRCT of the chest. Patients had some investigations like serology, and when required surgical lung biopsy. Image analysis was done by two independent and blinded readers for the pulmonary and extra-pulmonary finding of ILF-RADS. The pulmonary findings were 13 items and extrapulmonary findings were 5 items. The score was 5 types according to ILF-RADS: ILF-RADS 0 (incomplete assessment), ILF-RADS 1 (typical UIP), ILF-RADS 2 (probable UIP), ILF-RADS 3 (indeterminate UIP), ILF-RADS 4 (CT features most consistent with non-UIP diagnosis).

RESULTS

There was an excellent interobserver agreement of both reviewers for overall ILF-RADS (K = 0.88, P = 0.001) with 95.4% agreement. There was an excellent interobserver agreement for overall pulmonary findings (K = 0.901, 95% CI = 0.877-0.926, P = 0.001), excellent interobserver agreement for seven items including lung volume, traction bronchiectasis, nodules, cysts, consolidation, emphysema, and complications and moderate interobserver agreement for six items including reticulations, honeycomb, ground glass, mosaic attenuation, and axial and zonal distribution. There was excellent interobserver agreement for overall extra-pulmonary findings (K = 0.902, 95% CI = 0.852-0.952, P = 0.001), excellent interobserver agreement for four items including mediastinum, pleura, visible abdomen, and soft tissue and bone and moderate interobserver agreement for trachea and main bronchi. There was excellent interobserver agreement for ILF-RADS score: ILF-RADS 1 (K = 0.84, P = 0.001), ILF-RADS 3 (K = 0.881, P = 0.001), and ILF-RADS 4 (K = 0.878, 95% CI = 0.743-1.0, P = 0.001) and moderate interobserver agreement for ILF-RADS 2 (K = 0.784, P = 0.001).

CONCLUSION

ILF-RADS is a reliable reporting system which can be routinely performed for standard interpretation of ILD.

Interstitial Lung Disease in Connective Tissue Disease: A Common Lesion With Heterogeneous Mechanisms and Treatment Considerations

Connective tissue disease (CTD) related interstitial lung disease (CTD-ILD) is one of the leading causes of morbidity and mortality of CTD. Clinically, CTD-ILD is highly heterogenous and involves rheumatic immunity and multiple manifestations of respiratory complications affecting the airways, vessels, lung parenchyma, pleura, and respiratory muscles. The major pathological features of CTD are chronic inflammation of blood vessels and connective tissues, which can affect any organ leading to multi-system damage. The human lung is particularly vulnerable to such damage because anatomically it is abundant with collagen and blood vessels. The complex etiology of CTD-ILD includes genetic risks, epigenetic changes, and dysregulated immunity, which interact leading to disease under various ill-defined environmental triggers. CTD-ILD exhibits a broad spectra of clinical manifestations: from asymptomatic to severe dyspnea; from single-organ respiratory system involvement to multi-organ involvement. The disease course is also featured by remissions and relapses. It can range from stability or slow progression over several years to rapid deterioration. It can also present clinically as highly progressive from the initial onset of disease. Currently, the diagnosis of CTD-ILD is primarily based on distinct pathology subtype(s), imaging, as well as related CTD and autoantibodies profiles. Meticulous comprehensive clinical and laboratory assessment to improve the diagnostic process and management strategies are much needed. In this review, we focus on examining the pathogenesis of CTD-ILD with respect to genetics, environmental factors, and immunological factors. We also discuss the current state of knowledge and elaborate on the clinical characteristics of CTD-ILD, distinct pathohistological subtypes, imaging features, and related autoantibodies. Furthermore, we comment on the identification of high-risk patients and address how to stratify patients for precision medicine management approaches.

Progression of traction bronchiectasis/bronchiolectasis in interstitial lung abnormalities is associated with increased all-cause mortality: Age Gene/Environment Susceptibility-Reykjavik Study

PURPOSE

The aim of this study is to assess the role of traction bronchiectasis/bronchiolectasis and its progression as a predictor for early fibrosis in interstitial lung abnormalities (ILA).

METHODS

Three hundred twenty-seven ILA participants out of 5764 in the Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study who had undergone chest CT twice with an interval of approximately five-years were enrolled in this study. Traction bronchiectasis/bronchiolectasis index (TBI) was classified on a four-point scale: 0, ILA without traction bronchiectasis/bronchiolectasis; 1, ILA with bronchiolectasis but without bronchiectasis or architectural distortion; 2, ILA with mild to moderate traction bronchiectasis; 3, ILA and severe traction bronchiectasis and/or honeycombing. Traction bronchiectasis (TB) progression was classified on a five-point scale: 1, Improved; 2, Probably improved; 3, No change; 4, Probably progressed; 5, Progressed. Overall survival (OS) among participants with different TB Progression Score and between the TB progression group and No TB progression group was also investigated. Hazard radio (HR) was estimated with Cox proportional hazards model.

RESULTS

The higher the TBI at baseline, the higher TB Progression Score (P < 0.001). All five participants with TBI = 3 at baseline progressed; 46 (90 %) of 51 participants with TBI = 2 progressed. TB progression was also associated with shorter OS with statistically significant difference (adjusted HR = 1.68, P < 0.001).

CONCLUSION

TB progression was visualized on chest CT frequently and clearly. It has the potential to be the predictor for poorer prognosis of ILA.

Interstitial pneumonitis related to trastuzumab deruxtecan, a human epidermal growth factor receptor 2-targeting Ab-drug conjugate, in monkeys

Trastuzumab deruxtecan (T‐DXd: DS‐8201a) is an anti‐human epidermal growth factor receptor 2 (HER2) Ab–drug conjugated with deruxtecan (DXd), a derivative of exatecan. The objective of this study was to characterize T‐DXd‐induced lung toxicity in cynomolgus monkeys. Trastuzumab deruxtecan was injected i.v. into monkeys once every 3 weeks for 6 weeks (10, 30, and 78.8 mg/kg) or for 3 months (3, 10, and 30 mg/kg). To evaluate the involvement of DXd alone in T‐DXd‐induced toxicity, DXd monohydrate was given i.v. to monkeys once a week for 4 weeks (1, 3, and 12 mg/kg). Interstitial pneumonitis was observed in monkeys given T‐DXd at 30 mg/kg or more. The histopathological features of diffuse lymphocytic infiltrates and slight fibrosis were similar to interstitial lung diseases (ILD)/pneumonitis related to anticancer drugs in patients, with an incidence that was dose‐dependent and dose‐frequency‐dependent. Monkeys receiving DXd monohydrate did not suffer lung toxicity, although the DXd exposure level was higher than that of DXd in the monkeys given T‐DXd. The HER2 expression in monkey lungs was limited to the bronchial level, although the lesions were found at the alveolar level. Immunohistochemical analysis confirmed that T‐DXd localization was mainly in alveolar macrophages, but not pulmonary epithelial cells. These findings indicate that monkeys are an appropriate model for investigating T‐DXd‐related ILD/pneumonitis. The results are also valuable for hypothesis generation regarding the possible mechanism of T‐DXd‐induced ILD/pneumonitis in which target‐independent uptake of T‐DXd into alveolar macrophages could be involved. Further evaluation is necessary to clarify the mechanism of ILD/pneumonitis in patients with T‐DXd therapy.

Interstitial Lung Fibrosis Imaging Reporting and Data System: What Radiologist Wants to Know?

The aim of this work is to review interstitial lung fibrosis Imaging Reporting and Data System (ILF-RADS) that was designed for reporting of interstitial lung fibrosis (ILF). Findings include pulmonary and extrapulmonary findings and is subsequently designed into 4 categories. Pulmonary findings included lung volume, reticulations, traction bronchiectasis, honeycomb, nodules, cysts, ground glass, consolidation, mosaic attenuation and emphysema, and distribution of pulmonary lesions; axial (central, peripheral and diffuse), and zonal distribution (upper, middle, and lower zones). Complications in the form of acute infection, acute exacerbation, and malignancy were also assessed. Extrapulmonary findings included mediastinal, pleural, tracheal, and bone or soft tissue lesions. The lexicon of usual interstitial pneumonia (UIP) was classified into 4 categories designated as belonging in 1 of 4 categories. Lexicon of ILF-RADS-1 (typical UIP), ILF-RADS-2 (possible UIP), ILF-RADS-3 (indeterminate for UIP), and ILF-RADS-4 (inconsistent with UIP).