Presenting clinical and imaging features of patients with clinically amyopathic interstitial lung disease associated with myositis-specific autoantibodies.

Background: Lung involvement in the context of idiopathic inflammatory myopathies has significant impact on outcome; early and accurate diagnosis is important but can be difficult to achieve. In particular, patients without clinically evident muscle involvement pose a significant diagnostic challenge. Methods: A computer-assisted search was conducted to identify patients with amyopathic interstitial lung disease associated with the presence of myositis-specific autoantibodies. Medical records and chest imaging studies were reviewed to identify clinical and radiologic features at presentation. Results: Of the 35 patients with amyopathic interstitial lung disease associated with myositis-specific autoantibodies, the median age was 65 years (range 43-78) and 20 were women (57%). Of the patients, 34% had previously visited the rheumatology department. Presenting symptoms consisted of dyspnea (94%), cough (43%), and arthritis (23%). Raynaud phenomenon, "mechanic hands," Gottron papules, and inspiratory crackles were present in 23, 31, 9, and 74% of patients, respectively. After a detailed history, none of the patients reported muscle weakness, while four (11%) exhibited increased CK levels; of these four, two had a concomitant increase in aldolase levels. Median FVC was 79% predicted (range: 49-135) and median DLco was 50% predicted (range: 17-103). HRCT pattern was suggestive of an alternative to UIP pattern in 31/33 (94%) patients; the most common imaging patterns were NSIP (49%) and NSIP/OP (39%). Conclusion: In patients with NSIP and NSIP/OP pattern, the presence of amyopathic interstitial lung disease associated with myositis-specific autoantibodies should be considered even in the absence of clinical evident myositis.

A 74-Year-Old Man With Waldenström Macroglobulinemia and Progressive Dyspnea.

CASE PRESENTATION: A 74-year-old man presented to our department with progressive dyspnea on exertion over the last year. The patient did not report any other symptoms. He had previously smoked with a 60 pack-year history. He worked in an office and did not report any environmental, occupational, or domestic exposures. His history included asymptomatic Waldenström's macroglobulinemia that was diagnosed 18 months before respiratory symptoms. He was not receiving any treatment and was monitored regularly by the hematology department.

Expression of PD-1/PD-L1 axis in mediastinal lymph nodes and lung tissue of human and experimental lung fibrosis indicates a potential therapeutic target for idiopathic pulmonary fibrosis.

BACKGROUND: Mediastinal lymph node enlargement is prevalent in patients with idiopathic pulmonary fibrosis (IPF). Studies investigating whether this phenomenon reflects specific immunologic activation are lacking. METHODS: Programmed cell death-1 (PD-1)/ programmed cell death ligand-1 (PD-L1) expression in mediastinal lymph nodes and lung tissues was analyzed. PD-1, PD-L1 mRNA expression was measured in tracheobronchial lymph nodes of mice following bleomycin-induced injury on day 14. Finally, the effect of the PD-1 inhibitor, pembrolizumab, in bleomycin-induced pulmonary fibrosis was investigated. RESULTS: We analyzed mediastinal lymph nodes of thirty-three patients (n = 33, IPF: n = 14, lung cancer: n = 10, concomitant IPF and lung cancer: n = 9) and lung tissues of two hundred nineteen patients (n = 219, IPF: 123, controls: 96). PD-1 expression was increased, while PD-L1 expression was decreased, in mediastinal lymph nodes of patients with IPF compared to lung cancer and in IPF lungs compared to control lungs. Tracheobronchial lymph nodes isolated on day 14 from bleomycin-treated mice exhibited increased size and higher PD-1, PD-L1 mRNA levels compared to saline-treated animals. Pembrolizumab blunted bleomycin-induced lung fibrosis, as indicated by reduction in Ashcroft score and improvement in respiratory mechanics. CONCLUSIONS: Mediastinal lymph nodes of patients with IPF exhibit differential expression profiles than those of patients with lung cancer indicating distinct immune-mediated pathways regulating fibrogenesis and carcinogenesis. PD-1 expression in mediastinal lymph nodes is in line with lung tissue expression. Lower doses of pembrolizumab might exert antifibrotic effects. Clinical trials aiming to endotype patients based on mediastinal lymph node profiling and accordingly implement targeted therapies such as PD-1 inhibitors are greatly anticipated.

Diagnostic Utility of Bronchoalveolar Lavage Lymphocytosis in Patients with Interstitial Lung Diseases.

BACKGROUND: Interstitial lung diseases (ILDs) are extremely challenging in terms of diagnosis. Extreme bronchoalveolar lavage (BAL) lymphocytosis is thought to strongly point towards the diagnosis of hypersensitivity pneumonitis (HP). OBJECTIVES: Explore the range of different ILD that can present with BAL lymphocytosis, including cases of pronounced lymphocytosis and its diagnostic utility. METHODS: Patients with ILD that were subjected to BAL were identified retrospectively from a cohort of consecutive patients. RESULTS: BAL lymphocytosis ≥20% was recorded in 106 patients (27%), while pronounced BAL lymphocytosis ≥40% was recorded in 49 patients (12.5%). The most common diagnoses in patients with BAL lymphocytosis ≥20% and ≥40%, were HP (32.1%), connective tissue disease (CTD)-ILD (26.4%), sarcoidosis (16%), and HP (38.8%), CTD-ILD (24.5%), sarcoidosis (14.3%), respectively. CONCLUSIONS: Neither the presence nor the degree of BAL lymphocytosis can point to a specific diagnosis.

COVID-19 and protection of vaccination in patients with systemic sclerosis-associated interstitial lung disease.

Objectives: Data on COVID-19 in patients with interstitial lung disease are scarce and whether SARS-CoV-2 may trigger interstitial lung disease progression remains unknown. We aimed to analyze outcomes of COVID-19 in patients with systemic sclerosis-associated interstitial lung disease, including possible thoracic radiographic progression. Patients and Methods: All 43 patients with systemic sclerosis-associated interstitial lung disease followed in our center (mean ± SD, 55.2 ± 11.6 years, 36 female) with confirmed SARS-CoV2 infection up to 1 September 2022 were analyzed. Individual interstitial lung disease extent on high resolution CT (HRCT) performed before (up to 3 months) and after COVID-19 (2-5 months) was compared. Results: At SARS-CoV-2 infection, 9/43 patients were unvaccinated, whereas 5, 26, and 3 had received 2, 3, or 4 doses of an mRNA vaccine, respectively. Thirty-one patients were either on monotherapy with immunosuppressives (mycophenolate, n = 7; cyclophosphamide, n = 2; methotrexate, n = 10; tocilizumab, n = 7; rituximab, n = 1; etanercept, n = 1), or their combinations (n = 3). Eight patients (20%), of whom four unvaccinated, required hospitalization for pneumonia and three (7%) died of acute respiratory failure (n = 2, both unvaccinated) or cardiac arrest. Lack of vaccination was the only independent predictor for hospitalization (OR = 7.98, 95% CI: 1.25-51.09) and marginally for death (OR = 32.7, 95% CI: 0.97-1110.98), regardless of the presence of diffuse systemic sclerosis, interstitial lung disease extent greater than 20% or immunosuppressive treatment. In 22 patients with available HRCT pairs (vaccinated = 20), the interstitial lung disease extent before COVID-19 (20.4%± 17.8%) remained unchanged (22.4% ± 18.5%) in all but one patient. Conclusion: SARS-CoV-2 vaccination is of outmost importance for every systemic sclerosis patient with interstitial lung disease. COVID-19 does not seem to promote progression of systemic sclerosis-associated interstitial lung disease in vaccinated patients, but further studies are warranted.

SH2 Domain-Containing Phosphatase-SHP2 Attenuates Fibrotic Responses through Negative Regulation of Mitochondrial Metabolism in Lung Fibroblasts.

BACKGROUND: We have previously shown that SHP2 downregulation may predispose fibroblasts to differentiate into myofibroblasts and proposed a role for SHP2 downregulation in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Recent data have shown that SHP2 localizes to the mitochondrial intercristae, and its overexpression enhances mitochondrial metabolism leading to oxidative stress and senescence. OBJECTIVE: To determine the effect of SHP2 on fibrotic responses. METHODS AND RESULTS: Primary mouse lung fibroblasts derived from mice carrying a conditional knock-in mutation (D61G/+), rendering the SHP2 catalytic domain constitutively active, had reduced proliferation (1.6-fold, p < 0.05), migration (2-fold, p < 0.05), as well as reduced responsiveness of TGFB-1 induced fibroblasts-to-myofibroblasts differentiation, compared to wild-type ones. Electron microscope analysis revealed that SHP2 D61G/+ mouse lung fibroblasts were characterized by mitochondrial abnormalities, including swollen mitochondria with disrupted electron-lucent cristae and an increased number of autophagosomes compared to wild-type ones. SHP2 D61G/+ MLFs exhibited increased protein levels of autophagy markers, including LC3B-II and p-62, evidence that was confirmed by immunofluorescence analysis. Mitochondrial function analysis revealed that stable (genotype D61G/+) overexpression of SHP2 led to impaired mitochondrial function, as assessed by decreased mitochondrial membrane potential (1.29-fold, p < 0.05), coupling efficiency (1.82 fold, p < 0.05), oxygen consumption rate (1.9-fold, p < 0.05), and increased reactive oxygen species production both at baseline (1.75-fold, p < 0.05) and following H2O2 stimulation (1.63-fold, p < 0.05) compared to wild-type ones (SHP2+/+). SHP2 D61G/+ mouse lung fibroblasts showed enhanced AMPK activity, as well as decreased activation of the mTORC1 signaling pathway, potentially leading to ineffective mitochondrial metabolism and increased autophagy. CONCLUSIONS: SHP2 attenuates fibrotic responses in fibroblast cell lines through negative regulation of mitochondrial metabolism and induction of autophagy. SHP2 activation may represent a promising therapeutic strategy for patients with fibrotic lung diseases.

Lung cancer in patients with idiopathic pulmonary fibrosis: A retrospective multicentre study in Europe.

BACKGROUND AND OBJECTIVE: There remains a paucity of large databases for patients with idiopathic pulmonary fibrosis (IPF) and lung cancer. We aimed to create a European registry. METHODS: This was a multicentre, retrospective study across seven European countries between 1 January 2010 and 18 May 2021. RESULTS: We identified 324 patients with lung cancer among 3178 patients with IPF (prevalence = 10.2%). By the end of the 10 year-period following IPF diagnosis, 26.6% of alive patients with IPF had been diagnosed with lung cancer. Patients with IPF and lung cancer experienced increased risk of all-cause mortality than IPF patients without lung cancer (HR: 1.51, [95% CI: 1.22-1.86], p < 0.0001). All-cause mortality was significantly lower for patients with IPF and lung cancer with a monocyte count of either <0.60 or 0.60-<0.95 K/µl than patients with monocyte count ≥0.95 K/µl (HR [<0.60 vs. ≥0.95 K/µl]: 0.35, [95% CI: 0.17-0.72], HR [0.60-<0.95 vs. ≥0.95 K/µl]: 0.42, [95% CI: 0.21-0.82], p = 0.003). Patients with IPF and lung cancer that received antifibrotics presented with decreased all cause-mortality compared to those who did not receive antifibrotics (HR: 0.61, [95% CI: 0.42-0.87], p = 0.006). In the adjusted model, a significantly lower proportion of surgically treated patients with IPF and otherwise technically operable lung cancer experienced all-cause mortality compared to non-surgically treated patients (HR: 0.30 [95% CI: 0.11-0.86], p = 0.02). CONCLUSION: Lung cancer exerts a dramatic impact on patients with IPF. A consensus statement for the management of patients with IPF and lung cancer is sorely needed.

Reduced immunogenicity of the mRNA vaccine BNT162b2 in patients with idiopathic pulmonary fibrosis.

Patients with #IPF do not mount appreciable anti-spike antibody responses to two doses of #SARSCoV2 mRNA vaccine compared to the general population. National authorities should prioritise patients with IPF for booster doses. https://bit.ly/3K2KXQ0.

Idiopathic Pulmonary Fibrosis (an Update) and Progressive Pulmonary Fibrosis in Adults: An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline.

Background: This American Thoracic Society, European Respiratory Society, Japanese Respiratory Society, and Asociación Latinoamericana de Tórax guideline updates prior idiopathic pulmonary fibrosis (IPF) guidelines and addresses the progression of pulmonary fibrosis in patients with interstitial lung diseases (ILDs) other than IPF. Methods: A committee was composed of multidisciplinary experts in ILD, methodologists, and patient representatives. 1) Update of IPF: Radiological and histopathological criteria for IPF were updated by consensus. Questions about transbronchial lung cryobiopsy, genomic classifier testing, antacid medication, and antireflux surgery were informed by systematic reviews and answered with evidence-based recommendations using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. 2) Progressive pulmonary fibrosis (PPF): PPF was defined, and then radiological and physiological criteria for PPF were determined by consensus. Questions about pirfenidone and nintedanib were informed by systematic reviews and answered with evidence-based recommendations using the GRADE approach. Results:1) Update of IPF: A conditional recommendation was made to regard transbronchial lung cryobiopsy as an acceptable alternative to surgical lung biopsy in centers with appropriate expertise. No recommendation was made for or against genomic classifier testing. Conditional recommendations were made against antacid medication and antireflux surgery for the treatment of IPF. 2) PPF: PPF was defined as at least two of three criteria (worsening symptoms, radiological progression, and physiological progression) occurring within the past year with no alternative explanation in a patient with an ILD other than IPF. A conditional recommendation was made for nintedanib, and additional research into pirfenidone was recommended. Conclusions: The conditional recommendations in this guideline are intended to provide the basis for rational, informed decisions by clinicians.

Genotype-Phenotype Relationships in Inheritable Idiopathic Pulmonary Fibrosis: A Greek National Cohort Study.

BACKGROUND: Monogenic and polygenic inheritances are evidenced for idiopathic pulmonary fibrosis (IPF). Pathogenic variations in surfactant protein-related genes, telomere-related genes (TRGs), and a single-nucleotide polymorphism in the promoter of MUC5B gene encoding mucin 5B (rs35705950 T risk allele) are reported. This French-Greek collaborative study, Gen-Phen-Re-GreekS in inheritable IPF (iIPF), aimed to investigate genetic components and patients' characteristics in the Greek national IPF cohort with suspected heritability. PATIENTS AND METHODS: 150 patients with familial PF, personal-family extrapulmonary disease suggesting short telomere syndrome, and/or young age IPF were analyzed. RESULTS: MUC5B rs35705950 T risk allele was detected in 103 patients (90 heterozygous, 13 homozygous, allelic frequency of 39%), monoallelic TRG pathogenic variations in 19 patients (8 TERT, 5 TERC, 2 RTEL1, 2 PARN, 1 NOP10, and 1 NHP2), and biallelic ABCA3 pathogenic variations in 3. Overlapping MUC5B rs35705950 T risk allele and TRG pathogenic variations were shown in 11 patients (5 TERT, 3 TERC, 1 PARN, 1 NOP10, and 1 NHP2), MUC5B rs35705950 T risk allele, and biallelic ABCA3 pathogenic variations in 2. In 38 patients, neither MUC5B rs35705950 T risk allele nor TRG pathogenic variations were detectable. Kaplan-Meier curves showed differences in time-to-death (p = 0.025) where patients with MUC5B rs35705950 T risk allele alone or in combination with TRG pathogenic variations presented better prognosis. CONCLUSION: The Gen-Phen-Re-GreekS in iIPF identified multiple and overlapping genetic components including the rarest, underlying disease's genetic "richesse," complexity and heterogeneity. Time-to-death differences may relate to diverse IPF pathogenetic mechanisms implicating "personalized" medical care driven by genotypes in the near future.

Epidemiology of interstitial lung diseases and their progressive-fibrosing behaviour in six European countries.

The PERSEIDS study aimed to estimate incidence/prevalence of interstitial lung diseases (ILDs), fibrosing interstitial lung diseases (F-ILDs), idiopathic pulmonary fibrosis (IPF), systemic sclerosis-associated ILD (SSc-ILD), other non-IPF F-ILDs and their progressive-fibrosing (PF) forms in six European countries, as current data are scarce. This retrospective, two-phase study used aggregate data (2014-2018). In Phase 1, incident/prevalent cases of ILDs above were identified from clinical databases through an algorithm based on codes/keywords, and incidence/prevalence was estimated. For non-IPF F-ILDs, the relative percentage of subtypes was also determined. In Phase 2, a subset of non-IPF F-ILD cases was manually reviewed to determine the percentage of PF behaviour and usual interstitial pneumonia-like (UIP-like) pattern. A weighted mean percentage of progression was calculated for each country and used to extrapolate incidence/prevalence of progressive-fibrosing ILDs (PF-ILDs). In 2018, incidence/105 person-years ranged between 9.4 and 83.6 (ILDs), 7.7 and 76.2 (F-ILDs), 0.4 and 10.3 (IPF), 6.6 and 71.7 (non-IPF F-ILDs), and 0.3 and 1.5 (SSc-ILD); and prevalence/105 persons ranged between 33.6 and 247.4 (ILDs), 26.7 and 236.8 (F-ILDs), 2.8 and 31.0 (IPF), 22.3 and 205.8 (non-IPF F-ILDs), and 1.4 and 10.1 (SSc-ILD). Among non-IPF F-ILDs, sarcoidosis was the most frequent subtype. PF behaviour and UIP-like pattern were present in a third of non-IPF F-ILD cases each and hypersensitivity pneumonitis showed the highest percentage of progressive behaviour. Incidence of PF-ILDs ranged between 2.1 and 14.5/105 person-years, and prevalence between 6.9 and 78.0/105 persons. To our knowledge, PERSEIDS is the first study assessing incidence, prevalence and rate of progression of ILDs across several European countries. Still below the threshold for orphan diseases, the estimates obtained were higher and more variable than reported in previous studies, but differences in study design/population must be considered.

Safety and Effectiveness of Mycophenolate Mofetil in Interstitial Lung Diseases: Insights from a Machine Learning Radiographic Model.

INTRODUCTION: Treatment of interstitial lung diseases (ILDs) other than idiopathic pulmonary fibrosis (IPF) often includes systemic corticosteroids. Use of steroid-sparing agents is amenable to avoid potential side effects. METHODS: Functional indices and high-resolution computed tomography (HRCT) patterns of patients with non-IPF ILDs receiving mycophenolate mofetil (MMF) with a minimum follow-up of 1 year were analyzed. Two independent radiologists and a machine learning software system (Imbio 1.4.2.) evaluated HRCT patterns. RESULTS: Fifty-five (n = 55) patients were included in the analysis (male: 30 [55%], median age: 65.0 [95% CI: 59.7-70.0], mean forced vital capacity %predicted [FVC %pred.] ± standard deviation [SD]: 69.4 ± 18.3, mean diffusing capacity of lung for carbon monoxide %pred. ± SD: 40.8 ± 14.3, hypersensitivity pneumonitis: 26, connective tissue disease-ILDs [CTD-ILDs]: 22, other ILDs: 7). There was no significant difference in mean FVC %pred. post-6 months (1.59 ± 2.04) and 1 year (-0.39 ± 2.49) of treatment compared to baseline. Radiographic evaluation showed no significant difference between baseline and post-1 year %ground glass opacities (20.0 [95% CI: 14.4-30.0] vs. 20.0 [95% CI: 14.4-25.6]) and %reticulation (5.0 [95% CI: 2.0-15.6] vs. 7.5 [95% CI: 2.0-17.5]). A similar performance between expert radiologists and Imbio software analysis was observed in assessing ground glass opacities (intraclass correlation coefficient [ICC] = 0.73) and reticulation (ICC = 0.88). Fourteen patients (25.5%) reported at least one side effect and 8 patients (14.5%) switched to antifibrotics due to disease progression. CONCLUSION: Our data suggest that MMF is a safe and effective steroid-sparing agent leading to disease stabilization in a proportion of patients with non-IPF ILDs. Machine learning software systems may exhibit similar performance to specialist radiologists and represent fruitful diagnostic and prognostic tools.

Clinical features and outcomes of patients with myositis associated-interstitial lung disease.

Introduction: Myositis associated interstitial lung disease (ILD) seems to be an under-recognized entity. Methods: In this multicenter, retrospective study, we recorded between 9/12/2019 and 30/9/2021 consecutive patients who presented in five different ILD centers from two European countries (Greece, France) and received a multidisciplinary diagnosis of myositis associated-ILD. The primary outcome was all-cause mortality over 1 year in specific subgroups of patients. Secondary outcomes included comparison of disease characteristics between patients diagnosed with the amyopathic subtype and patients with evidence of myopathy at diagnosis. Results: We identified 75 patients with myositis associated-ILD. Median age (95% CI) at the time of diagnosis was 64.0 (61.0-65.0) years. Antinuclear antibody testing was positive in 40% of the cohort (n = 30/75). Myopathy onset occurred first in 40.0% of cases (n = 30), ILD without evidence of myopathy occurred in 29 patients (38.7%), while 16 patients (21.3%) were diagnosed concomitantly with ILD and myopathy. The commonest radiographic pattern was cellular non-specific interstitial pneumonia (NSIP) and was observed in 29 patients (38.7%). The radiographic pattern of organizing pneumonia was significantly more common in patients diagnosed with the amyopathic subtype compared to patients that presented with myopathy [24.1% (n = 7/29) vs. 6.5% (n = 3/46), p = 0.03]. One year survival was 86.7% in the overall population. Kaplan-Meier analysis demonstrated significantly higher all-cause 1-year mortality in patients with the amyopathic subtype compared to patients with evidence of myopathy [H R 4.24 (95% CI: 1.16-15.54), p = 0.03]. Patients diagnosed following hospitalization due to acute respiratory failure experienced increased risk of 1-year all-cause mortality compared to patients diagnosed in outpatient setting [HR 6.70 (95% CI: 1.19-37.81), p = 0.03]. Finally, patients with positive anti-MDA5 presented with higher 1-year all-cause mortality compared to anti-MDA5 negative patients [HR 28.37 (95% CI: 5.13-157.01), p = 0.0001]. Conclusion: Specific ILD radiographic patterns such as NSIP and organizing pneumonia may herald underlying inflammatory myopathies. Hospitalized patients presenting with bilateral organizing pneumonia refractory to antibiotics should be meticulously evaluated for myositis associated-ILD even if there is no overt muscular involvement. Incorporation of ILD radiological patterns in the diagnostic criteria of inflammatory myopathies may lead to timely therapeutic interventions and positively impact patients' survival.

Epidemiological characteristics and outcomes from 187 patients with COVID-19 admitted to 6 reference centers in Greece: an observational study during the first wave of the COVID-19 pandemic.

INTRODUCTION: Epidemiological data from patients with COVID-19 has been recently published in several countries. Nationwide data of hospitalized patients with COVID-19 in Greece remain scarce. MATERIAL AND METHODS: This was an observational, retrospective study from 6 reference centers between February 26 and May 15, 2020. RESULTS: The patients were mostly males (65.7%) and never smokers (57.2%) of median age 60 (95% CI: 57.6-64) years. The majority of the subjects (98%) were treated with the standard-of-care therapeutic regimen at that time, including hydroxychlo-roquine and azithromycin. Median time of hospitalization was 10 days (95% CI: 10-12). Twenty-five (13.3%) individuals were intubated and 8 died (4.2%). The patients with high neutrophil-to-lymphocyte ratio (NLR) ( > 3.58) exhibited more severe disease as indicated by significantly increased World Health Organization (WHO) R&D ordinal scale (4; 95% CI: 4-4 vs 3; 95% CI: 3-4, p = 0.0001) and MaxFiO2% (50; 95% CI: 38.2-50 vs 29.5; 95% CI: 21-31, p < 0.0001). The patients with increased lactate dehydrogenase (LDH) levels ( > 270 IU/ml) also exhibited more advanced disease compared to the low LDH group ( < 270 IU/ml) as indicated by both WHO R&D ordinal scale (4; 95% CI: 4-4 vs 4; 95% CI: 3-4, p = 0.0001) and MaxFiO2% (50; 95% CI: 35-60 vs 28; 95% CI: 21-31, p < 0.0001). CONCLUSION: We present the first epidemiological report from a low-incidence and mortality COVID-19 country. NLR and LDH may represent reliable disease prognosticators leading to timely treatment decisions.

A 58-Year-Old Woman With Lung Nodules and Chronic Cough.

CASE PRESENTATION: A 58-year-old woman was referred to our department with a cough of 1 year duration; her condition was unresponsive to the administration of inhaled steroid and beta-2 agonists. She denied the presence of dyspnea, chest pain, or other extrapulmonary symptoms. She was a never-smoker with a negative medical history and no occupational or domestic exposures. There was no history of cancer, gastroesophageal reflux disease, asthma, allergic rhinitis, or other allergies.

Antisynthetase Syndrome Masquerading as Hypersensitivity Pneumonitis.

Interstitial lung diseases (ILDs) cover a wide heterogeneous group of disorders, both of unknown and known causes. Accurate diagnosis is essential but, at the same time, presents many challenges. Typically, the distinction between idiopathic pulmonary fibrosis and fibrotic hypersensitivity pneumonitis (HP) can prove extremely difficult. However, another major, but underestimated, challenge is the diagnosis of connective tissue disease-associated ILD (CTD-ILD), specifically when ILD is the initial manifestation or when extrapulmonary manifestations are subclinical. Antisynthetase syndrome (ASyS) is a characteristic example where lung involvement can be the predominant feature in the absence of other evidence suggestive of CTD. In ASyS, lung involvement can be the initial manifestation or muscle involvement can be subclinical with normal muscle enzymes. Furthermore, a negative antinuclear antibody test does not indicate autoantibody negativity in the context of ASyS. Imaging and pathology findings in ASyS are not specific and overlap with other ILDs. Finally, bronchoalveolar lavage can exhibit pronounced lymphocytosis (>30-40%). The latter, in combination with a history of exposure to an inciting antigen, can lead to an erroneous diagnosis of HP with obvious negative impact on patients' outcome. Herein, we report 3 female patients aged 61, 65, and 70 years and 1 male patient aged 43 years, with ASyS masquerading as HP and analyze the underlying reasons of misdiagnosis, aiming to raise awareness of the need for close collaboration between pulmonologists and rheumatologists.