Pleuroparenchymal Fibroelastosis Research Articles

Pleuroparenchymal Fibroelastosis: Case Study

Pleuroparenchymal fibroelastosis is a rare and recently recognized condition, first described by Amitani et al. in the 1990s as fibrosis of the upper lobes and later recognized as a new clinicopathological entity by Frankel. In 2013, idiopathic pleuroparenchymal fibroelastosis was classified as a rare subtype in the international classification of idiopathic interstitial pneumonias. The disease can occur at any age, and the diagnosis issuspected in a patient with dyspnea and radiological presentation, characterized by fibrosis of the upper lobe of the pleural and subpleural pulmonary parenchyma. A definitive diagnosis is histopathological, characterized by dense intra-alveolar fibrosis with elastosis of the alveolar walls and fibrous thickening of the subpleural pleura, predominantly in the upper lobes. The disease progresses, with a poor prognosis, and currently, the only therapeutic option is lung transplantation. We describe a rare case of pleuroparenchymal fibroelastosisdiagnosed radiologically in an 83-year-old man

Prognostic value of coexisting conditions and complications in pleuroparenchymal fibroelastosis: a single-center retrospective study.

Pleuroparenchymal fibroelastosis (PPFE) is a rare idiopathic interstitial lung disease (ILD) characterized by subpleural parenchymal fibrosis and elastosis mainly in the upper lobes. PPFE occurs in a secondary form that overlaps with underlying medical conditions or complications. This study evaluated the clinical impact of coexisting factors on the survival of patients with PPFE. Fifty-five PPFE patients were retrospectively evaluated. The patients' diagnoses were categorized as "idiopathic PPFE" with no known cause or "secondary PPFE" with underlying medical conditions or complications. The clinical characteristics and survival rates of these groups were compared. Twenty-eight patients (50.9%) were diagnosed with idiopathic PPFE and 27 (49.1%) with secondary PPFE, including cases of occupational dust exposure, connective tissue disease (CTD), post-hematopoietic stem cell transplantation (HSCT), and a family history of ILD. The idiopathic and secondary PPFE groups had similar clinical features, laboratory tests, and pulmonary function profiles, including a low body mass index, normal Krebs von den Lungen-6, high surfactant protein-D, and high residual volume/total lung capacity. In the secondary PPFE group, post-HSCT was associated with a worse prognosis, and CTD was associated with better prognosis. A multivariate analysis demonstrated that post-HSCT and a reduced forced vital capacity were significantly associated with a worsened survival in patients with PPFE. The prognosis of PPFE is highly influenced by underlying medical conditions or complications. Patients with post-HSCT PPFE should be monitored particularly closely, as they are at higher risk of a poor prognosis than others.

Prognostic significance of body mass index and weight loss in patients with idiopathic pleuroparenchymal fibroelastosis.

Idiopathic pleuroparenchymal fibroelastosis (IPPFE) is a rare form of idiopathic interstitial pneumonias; its physical characteristics include a slender build with platythorax and progressive weight loss. However, the clinical significance of body mass index (BMI) and weight loss remains unclear in patients with IPPFE. Therefore, we aimed to clarify the association between baseline BMI, weight loss after diagnosis, and the prognosis of patients with IPPFE. This retrospective study included 71 patients diagnosed with IPPFE at our institution between 2005-2021. BMI at diagnosis was classified into three: underweight (<18.5 kg/m2), normal weight (≥18.5 to <25.0 kg/m2), or overweight (≥25.0 kg/m2). An annual rate of weight change after the diagnosis was evaluated, and ≥5% per year decrease was defined as a significant weight loss. We investigated clinical features and prognosis based on baseline BMI and weight loss. Of the 71 patients, 48 (67.6%) and 23 (32.4%) were classified as underweight and normal weight, respectively, and none were overweight. Significant weight loss occurred in 24 (33.8%) patients, and they tended to have more cases of dyspnea and had significantly older age, lower BMI, higher rates of co-existence of lower-lobe interstitial lung disease, lower pulmonary function test results and higher incidence of pneumothorax after the diagnosis than those without weight loss. Patients with BMI <18.5 kg/m2 and those with weight loss had a significantly worse prognosis than those with BMI ≥18.5 kg/m2 or those without weight loss, respectively (p=0.005, p<0.001). Multivariate analysis revealed that low BMI and weight loss were independent poor prognostic factors. Low BMI and weight loss are associated with poor prognosis in patients with IPPFE.

Proposed Clinical Algorithm for Pleuroparenchymal Fibroelastosis (PPFE).

Pleuroparenchymal fibroelastosis (PPFE) is characterized by fibrosis involving the pleura and subpleural lung parenchyma, predominantly in the upper lobes. As PPFE appears to occur in patients with heterogeneous etiologies, the disease course is thus also heterogenous, with some patients showing rapid progression while others have slow progression. Therefore, it is very difficult to predict prognosis with PPFE. Needless to say, this problematic matter has influenced the treatment strategy of PPFE patients. In fact, until now no evidence has been shown for use in creating an appropriate management algorithm for PPFE. We speculate that "uncoordinated breathing" is the most important reason for dyspnea in PPFE patients. Because monitoring of physique and not just pulmonary function and radiological evaluation is also very important, particularly in PPFE patients, this review focused on the characteristics of PPFE through an overview of previous studies in this field, and we proposed an algorithm as precision medicine based on the current evidence. Multiple views by the pulmonologist are needed to standardize a clinical algorithm that is necessary to correctly assess PPFE patients under the premise of maintenance of physique by providing appropriate nutritional care and pulmonary rehabilitation.

Outcomes of lung transplantation for pleuroparenchymal fibroelastosis: A French multicentric retrospective study

BackgroundPleuroparenchymal fibroelastosis (PPFE) has no currently available specific treatment. Benefits of lung transplantation (LT) for PPFE are poorly documented. MethodsWe conducted a nation-wide multicentric retrospective study in patients who underwent lung or heart-lung transplantation for chronic end-stage lung disease secondary to PPFE between 2012 and 2022 in France. ResultsThirty-one patients were included. At transplantation, median age was 48 years [IQR 35 – 55]. 64.5% were women. Twenty-one (67.7%) had idiopathic PFFE. Sixteen (52%) had bilateral LT, 10 (32%) had single LT, 4 (13%) had lobar transplantation and one (3%) had heart-lung transplantation. Operative mortality was 3.2%. Early mortality (< 90 days or during the first hospitalization) was 32%. Eleven patients (35.5%) underwent reoperation for hemostasis. Eight (30.8%) experienced bronchial complications. Mechanical ventilation time was 10 days [IQR 2–55]. Length of stay in intensive care unit and hospital were 34 [IQR 18–73] and 64 [IQR 36–103] days, respectively. Median survival was 21 months. Post-transplant survival rates after 1, 2, and 5 years were 57.9%, 42.6% and 38.3% respectively. Low albuminemia (p=0.046), FVC (p=0.021), FEV1 (p=0.009) and high emergency lung transplantation (p=0.04) were associated with increased early mortality. Oversized graft tended to be correlated to a higher mortality (p=0.07). ConclusionLT for PPFE is associated with high post-operative morbi-mortality rates. Patients requiring high emergency lung transplantation with advanced disease, malnutrition, or critical clinical status experienced worse outcomes. ClinicalTrials.gov IdentifierNCT05044390.

Clinical, radiological and histopathological features of patients with familial pulmonary fibrosis

BackgroundIn familial pulmonary fibrosis (FPF) at least two biological relatives are affected. Patients with FPF have diverse clinical features.Research questionWe aimed to characterize demographic and clinical features, re-evaluate high-resolution computed tomography (HRCT) scans and histopathology of surgical lung biopsies, assess survival and investigate the suitability of risk prediction models for FPF patients.Study designA retrospective cohort study.MethodsFPF data (n = 68) were collected from the medical records of Oulu University Hospital (OUH) and Oulaskangas District Hospital between 1 Jan 2000 and 11 Jan 2023. The inclusion criterion was pulmonary fibrosis (PF) (ICD 10-code J84.X) and at least one self-reported relative with PF. Clinical information was gathered from hospital medical records. HRCT scans and histology were re-evaluated.ResultsThirty-seven (54.4%) of the patients were men, and 31 (45.6%) were women. The mean ages of the women and men were 68.6 and 61.7 years, respectively (p = 0.003). Thirty-seven (54.4%) patients were nonsmokers. The most common radiological patterns were usual interstitial pneumonia (UIP) (51/75.0%), unclassifiable (8/11.8%) and nonspecific interstitial pneumonia (NSIP) (3/4.4%). Pleuroparenchymal fibroelastosis (PPFE) was observed as a single or combined pattern in 13.2% of the patients. According to the 2022 guidelines for idiopathic pulmonary fibrosis (IPF), the patients were categorized as UIP (31/45.6%), probable UIP (20/29.4%), indeterminate for UIP (7/10.3%) or alternative diagnosis (10/14.7%). The histopathological patterns were UIP (7/41.2%), probable UIP (1/5.9%), indeterminate for UIP (8/47.2%) and alternative diagnosis (1/5.9%). Rare genetic variants were found in 9 patients; these included telomerase reverse transcriptase (TERT, n = 6), telomerase RNA component (TERC, n = 2) and regulator of telomere elongation helicase 1 (RTEL1, n = 1). Half of the patients died (n = 29) or underwent lung transplantation (n = 5), with a median survival of 39.9 months. The risk prediction models composite physiology index (CPI), hazard ratio (HR) 1.07 (95.0% CI 1.04–1.10), and gender-age-physiology index (GAP) stage I predicted survival statistically significantly (p<0.001) compared to combined stages II and III.ConclusionsThis study confirmed the results of earlier studies showing that FPF patients’ radiological and histopathological patterns are diverse. Moreover, radiological and histological features revealed unusual patterns and their combinations.

Pleuroparenchymal fibroelastosis as a late complication of childhood cancer therapy: A case series.

Pleuroparenchymal fibroelastosis (PPFE) is a rare interstitial pneumonia with distinct clinicopathologic features. It has been associated with exposure to hematopoietic stem cell transplantation (HSCT) and classical alkylating agents. Here, we highlight PPFE as a late complication of childhood cancer therapy by describing the cases of four survivors of childhood cancer with a diagnosis of treatment-related PPFE. All patients received high-dose alkylating agents. PPFE should be considered in the differential diagnosis of restrictive lung disease in patients with history of exposure to alkylating agents or HSCT. Development of PPFE-specific, noninvasive diagnostic tools and disease-modifying therapies will clinically benefit these patients.

Platythorax increases residual volume/total lung capacity in idiopathic pleuroparenchymal fibroelastosis.

Platythorax significantly contributes to the increase in residual volume/total lung capacity ratio in patients with idiopathic pleuroparenchymal fibroelastosis https://bit.ly/3uZ0rmP.

Genetic Testing Goes Beyond Imaging and Histological Evaluation in Pleuroparenchymal Fibroelastosis

BackgroundLung biopsy remains the gold standard in the diagnosis of fibrotic interstitial lung disease (F-ILD), but there is a growing appreciation of the role of pathogenic gene variants in telomere and surfactant protein genes, especially in familial pulmonary fibrosis (FPF). Pleuroparenchymal fibroelastosis (PPFE) is a rare disease that can coexist with different patterns of F-ILD, including FPF. It can be progressive and often leads to respiratory failure and death. This study tested the hypothesis that genetic testing goes beyond radiological and histological findings in PPFE and other F-ILD further informing clinical decision-making for patients and affected family members by identifying pathological gene variants in telomere and surfactant protein genes.MethodsThis is a retrospective review of 70 patients with F-ILD in the setting of FPF or premature lung fibrosis. Six out of 70 patients were diagnosed with PPFE based on radiological or histological characteristics. All patients underwent telomere length evaluation in peripheral blood by Flow-FISH or genetic testing using a customized exome-based panel that included telomere and surfactant protein genes associated with lung fibrosis.ResultsHerein, we identified six individuals where radiographic or histopathological analyses of PPFE were linked with telomere biology disorders (TBD) or variants in surfactant protein genes. Each case involved individuals with either personal early-onset lung fibrosis or a family history of the disease. Assessments of telomere length and genetic testing offered insights beyond traditional radiological and histopathological evaluations.ConclusionDetecting anomalies in TBD-related or surfactant protein genes can significantly refine the diagnosis and treatment strategies for individuals with PPFE and other F-ILD.

Obstructive and Restrictive Lung Disease After Hematopoietic Stem Cell Transplantation

Pulmonary complications are frequently encountered by clinicians in patients who have undergone hematopoietic stem cell transplantation and are associated with increased morbidity and mortality in these patients. Complications involving the lung are caused by both infectious and non-infectious etiologies, with non- infectious complications associated with significant long-term effect on the quality of life and can occur several years after transplantation. One manifestation of non-infectious post-transplant complication is a change in pulmonary function testing compared to pre-transplant testing. These changes can either be of an obstructive or restrictive pattern with each being associated with specific post-transplant complications. An improved understanding of obstructive and restrictive lung disease after hematopoietic stem cell transplant is necessary for both primary care physicians and specialists to recognize these diseases early in their course in order to facilitate work-up, treatment, and necessary follow-up. This review will provide an overview of obstructive and restrictive lung disease after hematopoietic stem cell transplant focusing on the etiologies, diagnosis, treatment, and outcomes. We will highlight bronchiolitis obliterans syndrome as an example of obstructive disease after transplant and will discuss pleuroparenchymal fibroelastosis as a cause for restrictive findings on pulmonary function testing. Improvements in the knowledge of the underlying etiologies and pathophysiology of obstructive and restrictive lung disease after hematopoietic stem cell transplant will allow for the identification of novel biomarkers to facilitate the diagnosis of these patients and will assist in the design of future targeted therapies to improve treatment and prognosis.

Pleuro-Parenchymal Fibroelastosis (PPFE)-A Case Report

Pleuro-parenchymal fibroelastosis (PPFE) is a rare form of interstitial lung disease with pleural and parenchymal components in the form of fibrosis and elastosis. This is often missed due to its rarity and nonspecific symptoms. Most of the cases were attributed to trivial respiratory infections in the past. Here we present a case of an elderly female who is symptomatic after COVID-19 infection and has characteristic radiological patterns in high-resolution computed tomogram (HRCT) to suggest a diagnosis of PPFE.

Neutrophil–lymphocyte ratio in patients with idiopathic pleuroparenchymal fibroelastosis

BackgroundIdiopathic pleuroparenchymal fibroelastosis (iPPFE), a progressive fibrotic disease, is characterised by upper lobe–dominant lung fibrosis involving the pleura and subpleural lung parenchyma. However, no prognostic markers have been established for...

Anti-fibrotic effects of nintedanib on lung fibroblasts derived from patients with Progressive Fibrosing Interstitial Lung Diseases (PF-ILDs)

The tyrosine kinase inhibitor nintedanib has been recently approved for the treatment of Interstitial Lung Diseases (ILDs) that manifest a progressive fibrosis phenotype other than Idiopathic pulmonary Fibrosis (IPF).Nintedanib reduces the development of lung fibrosis in various animal models resembling features of PF-ILD and in vitro, it inhibits the fibrosing phenotype of human lung fibroblasts (HLFs) isolated from patients with IPF. To get insight on the cellular and molecular mechanisms that drive the clinical efficiency of nintedanib in patients with non-IPF PF-ILD, we investigated its effects on the fibrosing functions of HLFs derived from patients with PF-hypersensitivity pneumonitis (PF-HP, n = 7), PF-sarcoidosis (n = 5) and pleuroparenchymal fibroelastosis (PPFE, n = 4).HLFs were treated with nintedanib (10 nM-1 μM) and then stimulated with PDGF-BB (25–50 ng/ml) or TGF-β1 (1 ng/ml) for 24–72 h to assess proliferation and migration or differentiation.At nanomolar concentrations, nintedanib reduced the levels of PDGF receptor and ERK1/2 phosphorylation, the proliferation and the migration of PF-HP, PF-sarcoidosis and PPFE HLFs stimulated with PDGF-BB. Moreover, nintedanib also attenuates the myofibroblastic differentiation driven by TGF-β1 but only when it is used at 1 μM. The drug reduced the phosphorylation of SMAD2/3 and decreased the induction of collagen, fibronectin and α-smooth muscle actin expression induced by TGF-β1.In conclusion, our results demonstrate that nintedanib counteracts fundamental fibrosing functions of lung fibroblasts derived from patients with PF-HP, PF-sarcoidosis and PPFE, at concentrations previously reported to inhibit control and IPF HLFs. Such effects may contribute to its clinical benefit in patients suffering from these irreversible ILDs.

Prognostic impact of the cross-sectional area of the erector spinae muscle in patients with pleuroparenchymal fibroelastosis

Pleuroparenchymal fibroelastosis (PPFE) progresses slowly but sometimes relatively quickly, leading to decreased activities of daily living (ADL) and muscle weakness. Skeletal muscle atrophy and muscle weakness in chronic obstructive pulmonary disease (COPD) patients may be caused by cachexia and are associated with reduced ADLs and increased risk of death. However, the association between skeletal muscle mass and the prognosis of PPFE patients remains unknown. We retrospectively analysed the clinical significance of the cross-sectional area of the erector spinae muscle (ESMCSA), a skeletal muscle index, and predictors of mortality within 3 years in PPFE 51 patients, idiopathic pulmonary fibrosis (IPF) 52 patients and COPD 62 patients. PPFE patients had significantly lower ESMCSA than IPF or COPD patients, and lower ESMCSA (< 22.57 cm2) was associated with prognosis within 3 years (log-rank test; p = 0.006), whereas lower body mass index (BMI) showed no association. Multivariate analysis showed that ESMCSA was an independent predictor of mortality within 3 years in PPFE patients (hazard ratio, 0.854; 95% confidence interval: 0.737–0.990, p = 0.036). These results suggest the importance of monitoring ESMCSA in PPFE patients and that assessing ESMCSA in PPFE patients could be a more useful prognostic indicator than BMI.

ЭФФЕКТИВНОСТЬ КРАТКОСРОЧНОЙ РАР-ТЕРАПИИ У БОЛЬНЫХ ФИБРОЗИРУЮЩИМИ ИНТЕРСТИЦИАЛЬНЫМИ ЗАБОЛЕВАНИЯМИ ЛЕГКИХ

The results of the use of non-invasive lung ventilation (NIV) with the creation of positive airway pres-sure (Positive Airway Pressure) or PAP-therapy in patients with fibrosing interstitial lung diseases (FILD) are presented. The assessment of the initial functional status and the dynamics of changes was carried out using a cardiopulmonary exercising test (CPET). Objective: to evaluate the effectiveness of PAP-therapy, as one of the methods of respiratory support, in patients with FILD using CPET. Materi-als and Methods: The study included 35 patients with clinically-radiologically or histologically veri-fied FILD, among them, 60% were idiopathic pulmonary fibrosis, 31 % – exogenous fibrosing-type allergic alveolitis, 9 % – pleuroparenchymal fibroelastosis. All patients underwent CPET at baseline, after which they were randomized into 2 groups: the main group A – 18 people who received PAP-therapy for 1 month and the control group B – 17 people who did not receive respiratory therapy. A month later, all patients repeated CPET in dynamics. Results of the study: after 1 month of PAP-therapy in patients of the study, the main group A, there was a statistically significant change in some indicators of CPET, such as an improvement in the ventilation-perfusion ratio, in the form of a de-crease in the VD/VT (p = 0,09), an increase efficiency of the work performed (decrease in VO2/WR(p=0,02)), increase in the power of the work performed (MET (p=0,02), wt/kg (p=0,03)). In patients of the control group B after 1 month no statistically significant changes in CPET indicators were found. Comparative analysis between groups also confirmed more efficient oxygen delivery in group A. Conclusion: we can assume a positive effect of a short-term course of NIV respiratory sup-port on the functional status of the respiratory system in FILD patients, in particular, an improvement in the ventilation-perfusion balance at rest and during exercise, as well as an increase in exercise toler-ance.

High prevalence of upper lung field pulmonary fibrosis radiologically consistent with pleuroparenchymal fibroelastosis in patients with round atelectasis

BackgroundUpper-lung field pulmonary fibrosis (upper-PF), radiologically consistent with pleuroparenchymal fibroelastosis (PPFE), was reported to develop in patients with a history of asbestos exposure and tuberculous pleurisy, indicating that chronic pleuritis is correlated with upper-PF development. Round atelectasis reportedly emerges after chronic pleuritis. This study aimed to clarify the association between round atelectasis and upper-PF. MethodsWe examined the radiological reports of all consecutive patients with round atelectasis between 2006 and 2018 and investigated the incidence of upper-PF development. ResultsAmong 85 patients with round atelectasis, 21 patients (24.7%) were confirmed to finally develop upper-PF lesions. Upper-PF was diagnosed after round atelectasis recognition in more than half of the patients (13/21, 61.9%), whereas upper-PF and round atelectasis were simultaneously detected in the remaining 8 patients. At the time of round atelectasis detection, almost all patients (19/21, 90.5%) had diffuse pleural thickening and round atelectasis was commonly observed in non-upper lobes of 19 patients (90.5%). Fourteen patients had round atelectasis in unilateral lung, and the remaining 7 patients had round atelectasis in bilateral lungs. Among all 14 patients with unilateral round atelectasis, upper-PF developed on the same (n = 11) or both sides (n = 3). Thus, upper-PF emerged on the same side where round atelectasis was present (14/14, 100%). The autopsy of one patient revealed a thickened parietal-visceral pleura suggestive of chronic pleuritis. Subpleural fibroelastosis was also observed. ConclusionsUpper-PF occasionally develops on the same side of round atelectasis. Upper-PF may develop as a sequela of chronic pleuritis.

Establishing quantitative radiographic criteria for the diagnosis of pleuroparenchymal fibroelastosis

PurposePleuroparenchymal Fibroelastosis (PPFE) is a type of pulmonary fibrosis most commonly occurring at the apices. Patients with PPFE have an increased risk of adverse effects from lung biopsy and in the post-surgical setting. Here, we investigated simple and reproducible measurements on chest CT to evaluate their predictive value in diagnosing PPFE. MethodsWe analyzed a cohort of patients with histologically-proven PPFE and compared them to a cohort of patients diagnosed with “biapical scarring” (BAS) on chest CT. We measured plueuroparenchymal thickness using several independent parameters on chest CT. We also assessed other radiologic and clinical characteristics to identify if any were predictive of PPFF. ResultsOur analysis demonstrated the average greatest apical thickness with a cut off of 4.5 mm yielded a sensitivity of 94.4% and a specificity of 88.9%, and an area under the curve of 97.2%. Single greatest apical thickness with a cut off of 7.5 mm had a sensitivity of 100% and a specificity of 88.9%, with the area under the curve of 97.8%. Average greatest upper lobe thickness with a cut off of 8.0 mm had a sensitivity of 88.9% and a specificity of 100%, with an area under the curve of 98.2%. Single greatest upper lobe thickness with a cut off of 8.5 yielded both a sensitivity and specificity of 94.4% and an area under the curve of 94.3%. ConclusionMeasurements described above are highly sensitive and specific for the diagnosis of PPFE and warrant investigation with a larger cohort of patients.

Diagnoses and treatments for participants with interstitial lung abnormalities detected in the Yorkshire Lung Screening Trial

IntroductionInterstitial lung abnormalities (ILA) are relatively common incidental findings in participants undergoing low-dose CT screening for lung cancer. Some ILA are transient and inconsequential, but others represent interstitial lung disease...

A commonly misdiagnosed rare pulmonary disease: Idiopathic pleuroparenchymal fibroelastosis

A commonly misdiagnosed rare pulmonary disease: Idiopathic pleuroparenchymal fibroelastosis

Clinical significance of para-carinal air cysts in patients with pleuroparenchymal fibroelastosis: The relationship with pneumomediastinum and pneumothorax.

Para-tracheal or para-carinal air cysts (PACs) are often asymptomatic and usually detected incidentally by methods such as computed tomography. Their clinical significance is unclear in patients with pleuroparenchymal fibroelastosis (PPFE). We evaluated the clinical significance of PACs in PPFE and their relationship with pneumomediastinum or pneumothorax. In total, 50 patients had PPFE and 34 (68%) had PACs. Most PACs were para-carinal (n = 30). A para-tracheal air cyst was detected in only nine patients, which included five patients having both para-carinal and para-tracheal air cysts. Overall median survival was 24.7months. Survival was not significantly different between the patients with [PACs(+)] and without PACs (P = 0.268). A high frequency (64%) of the complication of pneumomediastinum or pneumothorax occurred in the overall population during follow-up. Pneumomediastinum/pneumothorax occurred significantly more frequently in patients with PACs(+) than in those without (76.5% vs. 37.5%; P = 0.012). PACs(+) was the only significant risk factor for pneumomediastinum/pneumothorax. Our data showed that PACs commonly occur in patients with PPFE, and most PACs were para-carinal air cysts. Additionally, PACs(+) was a significant risk factor for pneumomediastinum/pneumothorax; therefore, clinicians should be more aware of these complications during follow-up examination, particular in PACs(+) patients with PPFE.