Relapsing bronchopneumonia due to community-associated methicillin-resistant Staphylococcus aureus: a case report.

BACKGROUND: The emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has increased the incidence of community-onset MRSA infection. Respiratory tract infections caused by MRSA has been noted for their severity; however, repeated relapses that require extended antibiotic therapy are rare. CASE PRESENTATION: We report a case of relapsing bronchopneumonia caused by CA-MRSA in a 56-year-old man. The patient responded to antibiotics, but repeatedly relapsed after stopping treatment. MRSA was consistently isolated from airway specimens during each relapse. Extended oral antibiotic treatment with trimethoprim/sulfamethoxazole (TMP/SMX) for 6 months achieved infection control. Whole-genome sequencing of the isolated strain revealed that the causative agent was sequence type (ST)1/staphylococcal cassette chromosome mec (SCCmec) type IVa, a clone that is rapidly increasing in Japan. DISCUSSION AND CONCLUSIONS: This patient had an unusual course of MRSA bronchopneumonia with repeated relapses. Although the choice of antibiotics for long-term use in MRSA respiratory tract infections has not been well established, TMP/SMX was effective and well tolerated for long-term therapy in this case. The clinical course of infections related to the rapid emerging clone, ST1/SCCmec type IVa warrants further attention.

A Case of Solitary Pure Ground-glass Opacity Suspected of Being the Initial Presentation of Nonfibrotic Hypersensitivity Pneumonitis.

We herein report a rare case of hypersensitivity pneumonitis (HP) that was initially demonstrated as solitary pure ground-glass opacity (GGO) on chest computed tomography (CT). A 51-year-old woman with a history of breast cancer underwent follow-up CT, which revealed solitary pure GGO. The patient developed exertional dyspnea after two years, and CT revealed diffuse centrilobular nodules in addition to GGO, which had increased in size. An antigen avoidance test was performed to diagnose HP, leading to the resolution of CT abnormalities, including the GGO. Our findings suggested that nonfibrotic HP can present as solitary pure GGO.

Assessment of clinical relevance of antigen improves diagnostic accuracy of hypersensitivity pneumonitis.

BACKGROUND: Exposure assessment is integral to the diagnosis of hypersensitivity pneumonitis (HP). Although the clinical relevance of exposed antigens is essential for the assessment, many of the previous guidelines or reports have only evaluated simple exposure histories or immunological tests. To overcome this problem, the Exposure Assessment Form (EAF) was developed as an assessment tool for classifying the exposure grade from G0 to G4. The EAF was modified from the description in the Japanese clinical practice guide 2022 for HP published by the Japanese Respiratory Society. METHODS: One hundred and seventy-two consecutive patients with interstitial lung disease who underwent multidisciplinary discussion (MDD) at our hospital were retrospectively examined. We assessed whether the use of the EAF improved the diagnostic performance of the international guideline of HP. We also evaluated whether the exposure grade affected the prognosis of HP. RESULTS: Even when a HP diagnosis was made with a confidence of 70% or higher according to the international guideline, less than half of these cases resulted in a final diagnosis of HP when the exposure grades were lower than G3. When the result of the EAF was integrated into the exposure definition of the international guideline, the specificity of the diagnostic performance improved, while sensitivity was maintained. Furthermore, HP patients with an exposure grade of G3 or higher showed a tendency to take a longer time to initiate medication. CONCLUSIONS: This is the first study to evaluate the clinical relevance of possible antigens using the EAF. Assessing the exposure grade prevents overdiagnosis and improves the diagnostic performance of the international guideline.

Deep convolutional neural network for differentiating between sarcoidosis and lymphoma based on [18F]FDG maximum-intensity projection images.

OBJECTIVES: To compare the [18F]FDG PET/CT findings of untreated sarcoidosis and malignant lymphoma (ML) and develop convolutional neural network (CNN) models to differentiate between these diseases using maximum intensity projection (MIP) [18F]FDG PET images. METHODS: We retrospectively collected data on consecutive patients newly diagnosed with sarcoidosis and ML who underwent [18F]FDG PET/CT before treatment. Two nuclear radiologists reviewed the images. CNN models were created using MIP PET images and evaluated with k-fold cross-validation. The points of interest were visualized using gradient-weighted class activation mapping (Grad-CAM). RESULTS: A total of 56 patients with sarcoidosis and 62 patients with ML were included. Patients with sarcoidosis had more prominent FDG accumulation in the mediastinal lymph nodes and lung lesions, while those with ML had more prominent accumulation in the cervical lymph nodes (all p < 0.001). For the mediastinal lymph nodes, sarcoidosis patients had significant FDG accumulation in the level 2, 4, 7, and 10 lymph nodes (all p < 0.01). Otherwise, the accumulation in ML patients tended to be in the level 1 lymph nodes (p = 0.08). The CNN model using frontal and lateral MIP images achieved an average accuracy of 0.890 (95% CI: 0.804-0.977), a sensitivity of 0.898 (95% CI: 0.782-1.000), a specificity of 0.907 (95% CI: 0.799-1.000), and an area under the curve of 0.963 (95% CI: 0.899-1.000). Grad-CAM showed that the model focused on the sites of abnormal FDG accumulation. CONCLUSIONS: CNN models based on differences in FDG accumulation sites archive high performance in differentiating between sarcoidosis and ML. CLINICAL RELEVANCE STATEMENT: We developed a CNN model using MIP images of [18F]FDG PET/CT to distinguish between sarcoidosis and malignant lymphoma. It achieved high performance and could be useful in diagnosing diseases with involvement across organs and lymph nodes. KEY POINTS: • There are differences in FDG distribution when comparing whole-body [18F]FDG PET/CT findings in patients with sarcoidosis and malignant lymphoma before treatment. • Convolutional neural networks, a type of deep learning technique, trained with maximum-intensity projection PET images from two angles showed high performance. • A deep learning model that utilizes differences in FDG distribution may be helpful in differentiating between diseases with lesions that are characteristically widespread among organs and lymph nodes.

Effect of warm and humid days on the positivity rate of anti-Trichosporon asahii antibody test for the diagnosis of summer-type hypersensitivity pneumonitis.

BACKGROUND: Summer-type hypersensitivity pneumonitis (SHP) has been reported to occur during warm and humid summer seasons in Japan; however, the effect of weather conditions on SHP remains unknown. Anti-Trichosporon asahii antibody (TaAb) test is highly specific and useful for the diagnosing SHP. Therefore, we aimed to investigate the impact of weather conditions on SHP by examining the relationship between the positivity rate of TaAb and warm and humid days. METHODS: TaAb test data from June 2013 to June 2020 were obtained from major commercial laboratories to determine the number of samples and positivity rate of TaAb by prefecture. Using the Japan Meteorological Agency database, we counted the warm and humid days (maximum temperature ≥25 °C and average humidity ≥80 %) for each prefecture. Negative binomial regression was employed to examine the relationship between the positivity rate of TaAb and the number of warm and humid days per month. RESULTS: A total of 79,211 samples and 7626 positive samples (9.6 %) were identified. We found that the number of warm and humid days, 1 or 2 months prior to testing for TaAb, was associated with the positivity rate of the test. An increase in the positivity rate by 1.6 % and 2.9 % was observed with every 1-day increase in warm and humid days 1 month and 2 months before the test, respectively. CONCLUSIONS: Our TaAb analysis revealed a significant increase in TaAb positivity 1 or 2 months after periods of warm and humid days.

Tolerability of sotorasib for KRAS positive lung adenocarcinoma patient with pre-existing interstitial pneumonia; A case report.

A 74-year-old man was referred to our hospital with an abnormal chest shadow. Computed tomography (CT) revealed a mass in the left upper lobe and interstitial pneumonia (IP). The patient underwent CT-guided needle biopsy and was diagnosed as lung adenocarcinoma with cT2aN1M1a Stage IVA (PUL). The patient was administered 6 cycles of CBDCA + nab-paclitaxel as first-line, 3 cycles of atezolizumab as second-line, and 8 cycles of S-1 as third-line treatment but finally showed tumor progression. Because comprehensive genome profiling test revealed KRAS G12C mutation, sotorasib was initiated as fourth-line treatment and showed tumor regression without exacerbation of pre-existing IP.

Pulmonary Artery Aneurysm in a Patient with Nontuberculous Mycobacteria Infection.

Nontuberculous mycobacterial (NTM) infection sometimes leads to the development of pulmonary artery aneurysm (PAA), a rare but life-threatening complication. We herein report a 64-year-old woman with a history of NTM infection who presented with severe hemoptysis. Computed tomography revealed a ruptured PAA, which was treated successfully with pulmonary artery embolization. Subsequent right total pneumonectomy was performed to control infection. This case emphasizes the need to consider PAA in patients with NTM infection who present with hemoptysis. Early detection and appropriate management are critical for preventing this fatal complication.

COVID-19 Pneumonia Followed by Anti-signal Recognition Particle Antibody-positive Fibrosing Interstitial Lung Disease.

Coronavirus disease 2019 (COVID-19) pneumonia is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is frequently accompanied by various sequelae. Interstitial lung diseases (ILDs) are observed in COVID-19 pneumonia patients after recovery, probably due to persistent inflammation in the lungs. We herein report a case of ILD with anti-signal recognition particle antibodies following severe COVID-19 pneumonia. The patient was diagnosed with ILD three months after COVID-19 pneumonia. Although the exact mechanism is unknown, the autoantibody-induced immune response might have been the pulmonary fibrosis trigger in this patient.

Database analysis of hypersensitivity pneumonitis in Japan.

BACKGROUND: Three epidemiological small-scale studies on hypersensitivity pneumonitis (HP) have been performed in Japan to date. Herein, we aimed to clarify the clinical characteristics of various types of HP diseases using a large nationwide database in Japan. METHODS: We used the Japanese Diagnostic Procedure Combination database that includes data from 1,031 participant hospitals. Patients with HP from 2011 to 2017 were identified using International Classification of Diseases 10th Revision codes. We analyzed patient characteristics, the yearly transition of the number of HP cases, rate per one million hospitalizations, geographical distribution, seasonality, and risk factors for in-hospital mortality. RESULTS: In total, 3,634 patients with HP were identified, including summer-type HP (SHP) (n = 490), bird fancier's lung (BFL) (n = 199), ventilation pneumonitis (n = 106), farmer's lung (n = 48), and unspecified HP (n = 2761). The length of hospital stay was significantly longer in patients with BFL (19 days) than in patients with SHP (15 days). SHP was more prevalent in the southwestern region of Japan, and hospitalization occurred mainly in summer (37.8%) and fall (37.3%). Ventilation pneumonitis was predominant in winter (28.6%) and spring (38.7%). In-hospital mortality was significantly associated with old age (p < 0.001), low body mass index (p = 0.016), severe dyspnea (p < 0.001), and BFL diagnosis on admission (p = 0.031). CONCLUSIONS: This study revealed the clinical characteristics of SHP and BFL, including the frequency of causative antigens, geographical distribution, seasonality, and risk factors for mortality, which may help in diagnosing HP and identifying causative antigens.

A case of severe respiratory failure due to interstitial pneumonia successfully bridged to lung transplantation from a brain-dead donor using 109-day veno-arterial extracorporeal membrane oxygenation.

In Japan, successful cases of a bridge to lung transplantation (BTT) by extracorporeal membrane oxygenation (ECMO) are rare. We present the case of a man in his thirties, diagnosed with interstitial pneumonia 6 years prior and registered for lung transplant 1 year prior due to disease progression despite treatment. Due to the patient's worsening respiratory failure, he was transferred to our hospital for BTT by ECMO. Since long-term management was expected and pulmonary hypertension was present, veno-arterial (V-A) ECMO was conducted using the right atrial blood outflow via the right internal jugular vein and right axillary artery inflow via a vascular graft. After tracheostomy, he was managed as "Awake ECMO". In addition, interprofessional collaboration such as physiotherapist rehabilitation, nurses, and liaison teams prevented muscle weakness and supported the mental aspect. We were able to minimize complications such as severe infections and bleeding. A compatible brain-dead donor was found on day 108 after introducing ECMO, and the patient was transferred to a transplant facility on day 109. The peripheral upper V-A ECMO is one of the configurations suitable for long-term BTT management.

Muc5b plays a role in the development of inflammation and fibrosis in hypersensitivity pneumonitis induced by Saccharopolyspora rectivirgula.

Previously we have shown that a gain-of-function MUC5B promoter variant (rs35705950) is the strongest risk factor for the development of idiopathic pulmonary fibrosis. We have also found that Muc5b overexpression reduces mucociliary clearance in mice, potentially leading to recurrent injury to the bronchoalveolar epithelia. Hypersensitivity pneumonitis (HP) is induced by inhalation of numerous causative antigens that may be affected by mucociliary clearance. We conducted this study to determine the role of Muc5b in a mouse model of HP induced by Saccharopolyspora rectivirgula (SR) antigen. We used Muc5b-deficient and wild-type (WT) mice to determine whether Muc5b plays a role in inflammation and fibrosis at 3 and 6 wk in an SR model of HP. We measured cell concentrations and MUC5B expression in whole lung lavage (WLL) and quantified fibrosis using hydroxyproline assay and second harmonic generation. Muc5b expression in WLL fluid was significantly increased in SR-exposed WT mice compared with saline controls. WT mice challenged with SR developed more inflammation and lung fibrosis at 6 wk compared with 3 wk postexposure. Moreover, we found that 6 wk following challenge with SR, Muc5b-deficient mice had less lung inflammation and less lung fibrosis than Muc5b WT mice. Furthermore, Muc5b-deficient mice had significantly lower concentrations of TGF-ß1 in the WLL compared with Muc5b WT mice at 6 wk of exposure. Muc5b appears to play a role in fibrosis in the animal model of HP and this may have implications for HP in humans.

Association of SARS-CoV-2 RNA Copy Number with the COVID-19 Mortality Rate and Its Effect on the Predictive Performance of Mortality in Severe Cases.

Factors associated with mortality are important in the treatment of coronavirus disease 2019 (COVID-19). Polymerase chain reaction (PCR) is the gold standard for diagnosing COVID-19, which reflects the viral load in the upper respiratory tract. In total, 523 patients were enrolled in this study; of them, 441 and 75 patients underwent PCR testing of nasopharyngeal swabs and sputum samples, respectively, within 20 days from onset of COVID-19. We investigated the association between RNA copy number and the COVID-19 severity and mortality rate and its effect on the predictive performance for severity and mortality. RNA copy numbers in nasopharyngeal swabs were higher in the non-survivor group than in the survivor group. Multivariate logistic regression analysis identified that the high RNA copy number (≥9 log10 /swab) in nasopharyngeal swabs was a factor associated with mortality (odds ratio, 4.50; 95% confidence interval, 1.510-13.100; P = 0.008). Furthermore, adding RNA copy number (≥9 log10 /swab) in severe cases, adjusted by duration from onset to PCR, improved mortality predictive performance based on known factors. The RNA copy number is a factor associated with the mortality of patients with COVID-19 and can improve the predictive performance of mortality in severe cases.

Successful diagnosis of humidifier lung by individual provocation test to a responsible environment, a case report.

A 52-year-old woman presented with repeating episodes of pneumonia which spontaneously resolved after hospitalization. Hypersensitivity pneumonitis was suspected, but the causative antigen was not determined whether the parakeets she kept or the humidifier she owned was causative exposure. To identify which exposure is culprit, individual provocation test to a responsible environment was sequentially conducted. First, a home-returning provocation test to the parakeet was negative. Contrarily, the humidifier provocation test to her own humidifier was positive for symptoms, radiological changes, and inflammatory responses in blood test. Finally, she was diagnosed as having humidifier lung. When several antigens are suspected to be the causative agents for hypersensitivity pneumonitis, a step-by-step provocation tests is useful.

Profile of metastatic lung cancer patients susceptible to development of thromboembolism during immunotherapy.

BACKGROUND: Thromboembolism (TE) is a serious complication in lung cancer patients; however, risk factors for developing TE during treatment with immuno-oncology (IO) drugs are unclear. MATERIALS AND METHODS: A retrospective study of lung cancer patients hospitalized in Tokyo Medical and Dental University was performed to clarify the association between TE and systemic therapy, especially IOs. Patients were divided into an IO cohort, a chemotherapy cohort (CT cohort), and a control cohort (patients without recurrence after surgery). Association studies of variables relevant to TE were performed. RESULTS: A total of 592 patients were enrolled (IO cohort, 120; CT cohort, 294; control cohort, 178). Eight patients (6.7%) in the IO cohort, seven (2.4%) in the CT cohort, and three (1.7%) in the control cohort developed TE. Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis identified IO, a history of TE, poor performance status (PS), and prior anticoagulation therapy as being associated with TE. Subsequent multivariate logistic regression analysis identified a history of TE (odds ratio (OR), 6.03; 95% confidence interval (CI), 2.09-17.40; P = 0.01) and poor PS (OR, 3.84; 95% CI, 1.34-11.00; P < 0.001) as potential risk factors for developing TE. The incidence of TE in the IO cohort patients with both of these characteristics was significantly higher (OR, 52.82; 95% CI, 6.72-506.37; P < 0.001) than that in the control cohort. CONCLUSION: Lung cancer patients with a history of TE and poor PS are at increased risk of TE during treatment with IOs. MICRO ABSTRACT: The profiles of lung cancer patients susceptible to development of thromboembolism (TE) during immunotherapy are unclear, even though TE is associated with a worse prognosis. Here, association studies of variables relevant to TE revealed that patients with a history of TE and poor performance status are at higher risk of developing TE during immunotherapy.

Role of serum surfactant protein-D as a prognostic predictor in fibrotic hypersensitivity pneumonitis.

BACKGROUND: Serum Krebs von den Lungen-6 (KL-6) and surfactant protein-D (SP-D) are candidate diagnostic and activity markers for fibrotic hypersensitivity pneumonitis (HP), although their correlation with prognosis remains unclear. We aimed to evaluate the prognostic usefulness of serum KL-6 and SP-D in patients with fibrotic HP. METHODS: This was a retrospective medical record review of 185 patients with fibrotic HP at a single center from 2005 to 2019. The baseline and minimum serum KL-6 and SP-D levels over two years were recorded. The contribution of KL-6 and SP-D levels to the incidence of progressive fibrosing interstitial lung disease (PF-ILD) and mortality were evaluated using multivariate analysis. RESULTS: The respective baseline and minimum levels were 1441 and 808 U/ml for KL-6 and 254 and 132 ng/mL for SP-D. A high minimum SP-D level was significantly associated with a high incidence of PF-ILD by logistic regression, independent of baseline forced vital capacity and honeycombing. Similarly, a high minimum SP-D level was significantly associated with high mortality by Cox proportional hazard model analysis. The stratified minimum SP-D levels of <100, 100-200, and >200 revealed significantly distinct groups in the entire cohort, with PF-ILD incidence rates of 28%, 48%, and 74% and median survival times of 120, 74, and 45 months, respectively. CONCLUSIONS: High minimum SP-D levels over two years were correlated with an unfavorable prognosis in our cohort. Patient with consistently high SP-D levels during the clinical course may have a poor prognosis and be a candidate for early treatment intensification.

Alternative Gene Expression by TOLLIP Variant Is Associated With Lung Function in Chronic Hypersensitivity Pneumonitis.

BACKGROUND: Chronic hypersensitivity pneumonitis (CHP) is a heterogeneous fibrotic interstitial pneumonia resulting from the immune response of susceptible individuals to inhaled antigens. Genetic predispositions have been suggested in CHP; however, the link between susceptibility genes and fibrotic progression has not been elucidated fully. Recent data suggest that variants in Toll-interacting protein gene (TOLLIP) are associated with lung diseases. RESEARCH QUESTION: Can TOLLIP variants be associated with any clinical features in patients with CHP? STUDY DESIGN AND METHODS: We genotyped rs5743899 and rs3750920 in TOLLIP and analyzed the association with clinical parameters in 101 patients with CHP (67 for the retrospective cohort and 34 for the prospective cohort). We evaluated the expression of TOLLIP and fibrogenic signals in affected lung tissues and periostin in sera. Furthermore, we performed immunologic analysis in the lungs and sera. RESULTS: The rs5743899 GG genotype was associated with rapid deterioration in FVC over time, which demonstrated significant annual decline in the retrospective cohort (vs AA, P = .0006; vs AG, P < .0001), prospective cohort (vs AA, P < .0001; vs AG, P = .003), and combined cohort (both P < .0001). The patients with the GG genotype demonstrated lower transcription-translation levels of TOLLIP as well as increased phosphorylation of Smad2 and inhibitor of kappa B in the lung tissues and exhibited higher serum levels of periostin, IL-1α, IL-1ß, IL-6, IL-8, tumor necrosis factor α, and IFN-γ. INTERPRETATION: The functional changes by TOLLIP variant were associated with rapid FVC decline through dysregulated Smad/transforming growth factor ß and NF-κB signaling in CHP.

Arterial and Venous Thrombosis Complicated in COVID-19: A Retrospective Single Center Analysis in Japan.

Background: Thrombosis is a characteristic complication in coronavirus disease 2019 (COVID-19). Since coagulopathy has been observed over the entire clinical course, thrombosis might be a clue to understanding the specific pathology in COVID-19. Currently, there is limited epidemiological data of COVID-19-associated thrombosis in the Japanese population and none regarding variant strains of SARS-CoV-2. Here, we elucidate the risk factors and the pattern of thrombosis in COVID-19 patients. Methods: The patients consecutively admitted to Tokyo Medical and Dental University Hospital with COVID-19 were retrospectively analyzed. SARS-CoV-2 variants of concern/interest (VOC/VOI) carrying the spike protein mutants E484K, N501Y, or L452R were identified by PCR-based analysis. All thrombotic events were diagnosed by clinical symptoms, ultrasonography, and/or radiological tests. Results: Among the 516 patients, 32 patients experienced 42 thromboembolic events. Advanced age, severe respiratory conditions, and several abnormal laboratory markers were associated with the development of thrombosis. While thrombotic events occurred in 13% of the patients with a severe respiratory condition, those events still occurred in 2.5% of the patients who did not require oxygen therapy. Elevated D-dimer and ferritin levels on admission were independent risk factors of thrombosis (adjusted odds ratio 9.39 and 3.11, 95% confidence interval 2.08-42.3, and 1.06-9.17, respectively). Of the thrombotic events, 22 were venous, whereas 20 were arterial. While patients with thrombosis received anticoagulation and antiinflammatory therapies with a higher proportion, the mortality rate, organ dysfunctions, and bleeding complications in these patients were higher than those without thrombosis. The incidence of thrombosis in COVID-19 became less frequent over time, such as during the replacement of the earlier strains of SARS-CoV-2 by VOC/VOI and during increased use of anticoagulatory therapeutics. Conclusion: This study elucidated that elevated D-dimer and ferritin levels are useful biomarkers of thrombosis in COVID-19 patients. The comparable incidence of arterial thrombosis with venous thrombosis and the development of thrombosis in less severe patients required further considerations for the management of Japanese patients with COVID-19. Further studies would be required to identify high-risk populations and establish appropriate interventions for thrombotic complications in COVID-19.

Treatment of advanced lung cancer based on genomic profiling using liquid biopsy (plasma): A review of three cases.

Of the 80 solid tumor cases in which liquid biopsy (LB) was performed using Guardant360 in the PROFILE study, nine were lung cancer cases. Here, we review three cases in which LB was useful in diagnosing ALK fusion-positive lung cancer, selecting sequential ALK-tyrosine kinase inhibitors, confirming uncommon EGFR mutations, and receiving biomarker-compatible therapy.

Efficacy of treatment with corticosteroids for fibrotic hypersensitivity pneumonitis: a propensity score-matched cohort analysis.

BACKGROUND: Fibrotic hypersensitivity pneumonitis (HP) is a chronic interstitial lung disease caused by allergic responses to repeated exposures to a causative antigen. Therapeutic evidence of the use of corticosteroids to treat fibrotic HP remains lacking, although corticosteroids are recognized as a major treatment option. The purpose of this study was to evaluate the efficacy of corticosteroid treatment in patients with fibrotic HP in a propensity score-matched cohort. METHODS: A retrospective review of the medical records from 2005 to 2019 in a single center was conducted, and 144 patients with fibrotic HP were identified. Semiquantitative scores for lung abnormalities on HRCT were evaluated. Patients who received (PDN group) and did not receive (non-PDN group) corticosteroid treatment were matched using a propensity score method. Survival rates, serial changes in pulmonary function and annual changes in HRCT scores were compared in the matched cohort. RESULTS: In the matched analysis, 30 individuals in the PDN group were matched with 30 individuals in the non-PDN group, the majority of whom had ILD without extensive fibrosis. The survival rate was significantly better in the PDN group (P = 0.032 for the stratified Cox proportional hazards model; HR, 0.250). The absolute changes in FVC at 6, 12, and 24 months from baseline were significantly better in the PDN group. Fewer patients in the PDN group experienced annual deterioration, as reflected in the HRCT score, due to ground-glass attenuation, consolidation, reticulation, traction bronchiectasis and honeycombing. CONCLUSION: We demonstrated that corticosteroids improved survival and slowed fibrotic progression in a matched cohort, the majority of whom had ILD without extensive fibrosis. Fibrotic HP with less severe fibrosis may benefit from corticosteroid treatment. We propose that the early initiation of corticosteroids should be considered for fibrotic HP when worsening fibrosis is observed.