Relationship between idiopathic interstitial pneumonias (IIPs) and connective tissue disease-related interstitial lung disease (CTD-ILD): A narrative review

While idiopathic interstitial pneumonia (IIP) centering on idiopathic pulmonary fibrosis (IPF) is the most prevalent interstitial lung disease (ILD), especially in the older adult population, connective tissue disease (CTD)-related ILD is the second most prevalent ILD. The pathogenesis of IPF is primarily fibrosis, whereas that of other ILDs, particularly CTD-ILD, is mainly inflammation. Therefore, a precise diagnosis is crucial for selecting appropriate treatments, such as antifibrotic or immunosuppressive agents. In addition, some patients with IIP have CTD-related features, such as arthritis and skin eruption, but do not meet the criteria for any CTD, this is referred to as interstitial pneumonia with autoimmune features (IPAF). IPAF is closely associated with idiopathic nonspecific interstitial pneumonia (iNSIP) and cryptogenic organizing pneumonia (COP). Furthermore, patients with iNSIP or those with NSIP with OP overlap frequently develop polymyositis/dermatomyositis after the diagnosis of IIP. Acute exacerbation of ILD, the most common cause of death, occurs more frequently in patients with IPF than in those with other ILDs. Although acute exacerbation of CTD-ILD occurs at a low rate of incidence, patients with rheumatoid arthritis, microscopic polyangiitis, or systemic sclerosis experience more acute exacerbation of CTD-ILD than those with other CTD. In this review, the features of each IIP, focusing on CTD-related signatures, are summarized, and the pathogenesis and appropriate treatments to improve the prognoses of patients with various ILDs are discussed.

Radiological and histopathological features and treatment response by subtypes of interstitial pneumonia with autoimmune features: A prospective, multicentre cohort study

BACKGROUND

Patients with idiopathic interstitial pneumonia (IIP) have a favourable prognosis when they have interstitial pneumonia with autoimmune features (IPAF). However, precise IPAF-related findings from high-resolution computed tomography (HRCT) and lung histopathological specimens and the treatment response have not been fully determined. Therefore, this study was conducted to evaluate the relationship between findings on HRCT or lung histopathological specimens and the progression of interstitial pneumonia in patients with IPAF.

METHODS

This multicentre cohort study prospectively enrolled consecutive patients with IIP. At the diagnosis of IIP, we systematically evaluated 74 features suggestive of connective tissue diseases and followed them up. HRCT, lung specimens, serum antibodies, and the clinical course were also evaluated.

RESULTS

Among 222 patients with IIP, 26 (11.7%) fulfilled the IPAF criteria. During a median observation period of 36 months, patients with IPAF showed better survival than those without IPAF (p = 0.034). While histopathological findings were not related to IPAF, nonspecific interstitial pneumonia (NSIP) with organizing pneumonia (OP) overlap was the most prevalent HRCT pattern (p < 0.001) and the consolidation opacity was the most common radiological finding in IPAF (p = 0.017). Furthermore, in patients with IPAF, the diagnosis of COP or NSIP with OP overlap was associated with a higher increase in %FVC in 1 year than in those with idiopathic pulmonary fibrosis, NSIP, or unclassifiable IIP (p = 0.002).

CONCLUSIONS

This study shows the presence of consolidation opacity on HRCT and the diagnosis of COP or NSIP with OP overlap are associated with IPAF and its favourable treatment response in patients with IPAF.

Characteristics and risk factors of interstitial pneumonia with autoimmune features

BACKGROUND

Interstitial pneumonia with autoimmune features (IPAF) has features of connective tissue disease-associated interstitial lung disease (CTD-ILD), but without meeting criteria for a specific CTD. We compared baseline characteristics, survival, and response to treatment of IPAF to both CTD-ILD and unclassifiable ILD.

METHODS

Measurements were extracted from a prospective registry. Baseline features and survival were compared in IPAF against both CTD-ILD and unclassifiable ILD. Linear trajectory of lung function decline (%-predicted forced vital capacity [FVC%] and diffusion capacity of the lung for carbon monoxide [DLCO%]) before and after initiation of mycophenolate or azathioprine were compared in IPAF against both CTD-ILD and unclassifiable ILD using linear mixed models.

RESULTS

Compared to CTD-ILD (n = 1240), patients with IPAF (n = 128) were older, more frequently male, and had greater smoking history. Compared to unclassifiable ILD (n = 665), patients with IPAF were younger, more frequently female, and had worse baseline lung function. IPAF had higher mortality compared to CTD-ILD and similar risk of mortality compared to unclassifiable ILD. Mycophenolate initiation was associated with stabilization of FVC% and DLCO% in all ILD subtypes except for FVC% in patients with IPAF, and azathioprine initiation with stabilization of FVC% and DLCO% in all ILD subtypes except for FVC% decline in IPAF and DLCO% decline in CTD-ILD.

CONCLUSION

Patients with IPAF had worse survival compared to those with CTD-ILD and similar mortality to unclassifiable ILD, with treatment being associated with stabilization in lung function in all three ILDs. It is uncertain whether IPAF should be considered a distinct ILD diagnostic subgroup.

Interstitial pneumonia with autoimmune features and histologic usual interstitial pneumonia treated with anti-fibrotic versus immunosuppressive therapy

BACKGROUND

Therapeutic strategies in patients with interstitial pneumonia with autoimmune features (IPAF) and histological usual interstitial pneumonia (UIP) pattern (IPAF-UIP) have not been thoroughly evaluated. We compared the therapeutic efficacy of anti-fibrotic therapy with that of immunosuppressive treatment for patients with IPAF-UIP.

METHODS

In this retrospective case series, we identified consecutive IPAF-UIP patients treated with anti-fibrotic therapy or immunosuppressive therapy. Clinical characteristics, one-year treatment response, acute exacerbation, and survival were studied. We performed a stratified analysis by the pathological presence or absence of inflammatory cell infiltration.

RESULTS

Twenty-seven patients with anti-fibrotic therapy and 29 with immunosuppressive treatment were included. There was a significant difference in one-year forced vital capacity (FVC) change between patients with anti-fibrotic treatment (4 in 27 improved, 12 stable, and 11 worsened) and those with immunosuppressive treatment (16 in 29 improved, eight stable, and five worsened) (p = 0.006). There was also a significant difference in one-year St George's Respiratory Questionnaire (SGRQ) change between patients with anti-fibrotic therapy (2 in 27 improved, ten stable, and 15 worsened) and those with immunosuppressive treatment (14 in 29 improved, 12 stable, and worsened) (p < 0.001). There was no significant difference in survival between the groups (p = 0.32). However, in the subgroup with histological inflammatory cell infiltration, survival was significantly better with immunosuppressive therapy (p = 0.02).

CONCLUSION

In IPAF-UIP, immunosuppressive therapy seemed to be superior to anti-fibrotic treatment in terms of therapeutic response, and provided better outcomes in the histological inflammatory subgroup. Further prospective studies are needed to clarify the therapeutic strategy in IPAF-UIP.

Functional respiratory impairment and related factors in patients with interstitial pneumonia with autoimmune features (IPAF): Multicenter study from NEREA registry

BACKGROUND

The objective of the present study is to describe the characteristics of interstitial pneumonia with autoimmune features (IPAF) patients, to assess the incidence rate of functional respiratory impairment over time and to evaluate the influence of therapeutic alternatives on the prognosis of these patients.

METHODS

A longitudinal observational multicenter study was performed (NEREA registry). It was carried out by a multidisciplinary team in seven Hospitals of Madrid. Patients were included from IPAF diagnosis.

MAIN OUTCOME

poor prognosis as functional respiratory impairment (relative decline in FVC % defined as ≥ 5% every 6 months). Covariates: therapy, sociodemographic, clinical, radiological patterns, laboratory and functional tests.

STATISTICS

Survival techniques were used to estimate IR per 100 patients-semester with their 95% confidence interval [CI]. The influence of covariates in prognosis were analyzed through cox multivariate regression models (hazard ratio (HR) and [CI]).

RESULTS

79 IPAF were included, with a mean and a maximum follow-up of 3.17 and 12 years respectively. Along the study, 77.2% received treatment (52 glucocorticoids, 25 mycophenolate, 21 azathioprine, 15 rituximab and 11 antifibrotics). IR was 23.9 [19.9-28.8], and 50% of IPAF developed functional respiratory impairment after 16 months from its diagnosis. Multivariate analysis: usual interstitial pneumonia (UIP) had poorer prognosis compared to non-specific interstitial pneumonia (NSIP) (p = 0.001). In NSIP, positive ANA, increased the risk of poor prognosis. In UIP, glucocorticoids (HR: 0.53 [0.34-0.83]), age (HR: 1.04 [1.01-1.07]), and Ro-antibodies (HR: 0.36 [0.19-0.65]) influenced the prognosis.

CONCLUSIONS

IPAF have functional impairment during the first years of disease. Factors predicting deterioration differ between radiographic patterns. Our real-life study suggests the potential benefit of particular therapies in IPAF.

Interstitial Pneumonia with Autoimmune Features: What the Rheumatologist Needs to Know

PURPOSE OF REVIEW

This narrative review will focus on the role of the rheumatologist in evaluating patients with interstitial lung disease (ILD) without a defined rheumatic disease and will outline the current classification criteria for interstitial pneumonia with autoimmune features (IPAF) and describe what is known regarding IPAF pathobiology, natural history, prognosis, and treatment. Lastly, knowledge gaps and opportunities for future research will be discussed.

RECENT FINDINGS

IPAF is a recently defined classification of ILD patients who have features suggesting an autoimmune-mediated process, but do not fulfill current rheumatic disease criteria. The goal of the IPAF criteria is to provide a uniform case definition for the study of autoimmune ILD patients who do not currently fit within standard ILD diagnostic categories, ultimately improving diagnosis and therapy. Many of these patients are referred for rheumatologic evaluation to aid the diagnostic process. The care of the IPAF patient is complex and is multidisciplinary with pulmonology, rheumatology, pathology, radiology, physical therapy, primary care, pulmonary transplant providers all serving vital roles. The rheumatologist has several roles which include classification, disease monitoring, and management.

Management of Connective Tissue Disease-related Interstitial Lung Disease

Purpose of Review

This review aims to collate current evidence on the screening, diagnosis, and treatment of various connective tissue disease (CTD)–associated interstitial lung diseases (CTD-ILD) and present a contemporary framework for the management of such patients. It also seeks to summarize treatment outcomes including efficacy and safety of immunosuppressants, anti-fibrotics, and stem cell transplantation in CTD-ILD.

Recent Findings

Screening for ILD has been augmented by the use of artificial intelligence, ultra-low dose computerized tomography (CT) of the chest, and the use of chest ultrasound. Serum biomarkers have not found their way into clinical practice as yet. Identifying patients who need treatment and choosing the appropriate therapy is important to minimize the risk of therapy-related toxicity. The first-line drugs for systemic sclerosis (SSc) ILD include mycophenolate and cyclophosphamide. Nintedanib, an anti-fibrotic tyrosine kinase inhibitor, is approved for use in SSc-ILD. The US Food and Drug Administration (FDA) has recently approved tocilizumab subcutaneous injection for slowing the rate of decline in pulmonary function in adult patients with SSc-ILD. Autologous stem cell transplantation may have a role in select cases of SSc-ILD.

Summary

CTD-ILD is a challenging area with diverse entities and variable outcomes. High-resolution CT is the investigative modality of choice. Treatment decisions need to be individualized and are based on patient symptoms, lung function, radiologic abnormalities, and the risk of disease progression. Precision medicine may play an important role in determining the optimal therapy for an individual patient in the future.

Interstitial pneumonia with autoimmune features: Evaluation of connective tissue disease incidence during follow-up

OBJECTIVES

Among interstitial pneumonia with autoimmune features (IPAF) patients, identifying those at risk to develop a connective tissue disease (CTD) during the disease course is a key issue. The aim of this study was to evaluate the incidence of definite CTD diagnosis in IPAF patients during follow-up.

METHODS

We performed a multicentric cohort study of interstitial lung disease (ILD) from 2010 to 2017 in pneumology and immunology departments of tertiary care centers. Patients with a known cause of ILD (including established CTD) at diagnosis were excluded. Among patients with idiopathic ILD and at least three years of follow-up, two groups (IPAF and non-IPAF) were retrospectively analyzed at time of diagnosis.

RESULTS

A total of 249 patients with ILD were enrolled, including 70 IPAF and 179 non-IPAF patients. After a mean follow-up time of 77 ± 44 months, 18/70 IPAF patients (26%) had a CTD diagnosis - 9 antisynthetase syndrome, 8 systemic sclerosis and 1 overlap myositis - compared with 4/179 non-IPAF patients (2%). IPAF patients were at higher risk of CTD occurrence at 3 years of follow-up compared to non-IPAF patients (HR 10.1, 95% CI 3.1-33.1, p < 0. 01). IPAF patients progressing to CTD tended to be younger, more often female and have more frequently puffy fingers, capillaroscopy abnormalities and antisynthetase antibodies at diagnosis.

CONCLUSIONS

We found that a significant proportion of IPAF patients had associated CTD diagnosis during follow-up. Prospective studies are needed to confirm baseline predictive factors of CTD occurrence in IPAF patients.

[Treatment of lung fibrosis in systemic rheumatic diseases (new treatment)]

An interstitial lung disease represents a relevant organ manifestation in many systemic rheumatic diseases (connective tissue disease-interstitial lung disease, CTD-ILD). In 10% of the cases pulmonary fibrosis even results in an underlying systemic disease. The CTD-ILDs are frequently associated with a poor prognosis. Therefore, it is important to test patients with systemic rheumatic diseases timely and regularly for the presence of an ILD. Treatment decisions should be made together with pneumologists and rheumatologists, particularly with respect to the initiation of a specific treatment. Treatment is based on randomized studies only in a few cases and can mostly be derived from case control studies. For systemic sclerosis-associated ILD (SSc-ILD) antifibrotic treatment with nintedanib has also now been approved in addition to an immunosuppressive treatment. For other CTD-ILDs an antifibrotic treatment should be discussed in an interdisciplinary approach depending on the underlying disease corresponding to a progressively fibrosing ILD.

The Risk Factors of Exacerbation in Interstitial Pneumonia With Autoimmune Features: A Single-Center Observational Cohort Study

Objectives

To investigate the long-term outcomes, including risk factors, for exacerbation between monotherapy and combination therapy in patients with interstitial pneumonia with autoimmune features (IPAF).

Methods

We assessed 672 patients between April 2009 and March 2019 who were evaluated using high-resolution computed tomography (HRCT) of the chest. We applied the IPAF criteria. Fifty-two patients who visited our department for at least 6 months were diagnosed with IPAF. Clinical, laboratory, and imaging data were collected from medical records and statistically analyzed.

Results

Among the 52 cases of IPAF, we compared the characteristics at diagnosis between treated (n = 28) and untreated patients (n = 24). The exacerbation rates were 42.9% (n = 12) and 8.3% (n = 2) (P = 0.0051), respectively. Among the treated patients, smoking history, high titer of KL-6, and the duration from diagnosis to the start of treatment were significant risk factors for exacerbation (P = 0.0062, 0.011, and 0.019, respectively). The number of risk factors was significantly and positively associated with exacerbation rate (P = 0.0053). Among the treated patients, glucocorticoid (GC) monotherapy was used in 13 cases, and GC and immunosuppressant (IS) combination therapy was used in 14 patients. There was no significant difference in the treatment methods between patients with and without risk factors (P = 0.47). When comparing the long-term outcomes between the monotherapy and combination therapy groups, the 3-year non-exacerbation rates were 72.9 and 45.9% (P = 0.020), respectively.

Conclusions

IPAF patients with risk factors had a high exacerbation rate, regardless of the type of treatment. New interventions aimed at preventing exacerbations in these patients are required.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40744-021-00371-3.

Interstitial Lung Disease Associated with Connective Tissue Diseases

Pulmonary manifestations of connective tissue diseases (CTD) carry high morbidity and potential mortality, and the most serious pulmonary type is interstitial lung disease (ILD). Identifying and promptly intervening CTD-ILD with immune suppressor therapy will change the natural course of the disease resulting in survival improvement. Compared to idiopathic pulmonary fibrosis, the most common presentation of idiopathic interstitial pneumonia (IIP), CTD-ILD carries a better prognosis due to the response to immune suppressor therapy. Nonspecific interstitial pneumonia (NSIP) is the most common type of CTD-ILD that is different from the fibrotic classical presentation of IPF, known as usual interstitial pneumonia (UIP). An exception is rheumatoid arthritis that presents more frequently with UIP type. Occasionally, IPF may not have typical radiographic features of UIP, and a full assessment to differentiate IPF from CTD-ILD is necessary, including the intervention of a multidisciplinary team and the histopathology. Interstitial pneumonia with autoimmune features (IPAF) shows promising advantages to identify patients with ILD who have some features of a CTD without a defined autoimmune disease and who may benefit from immune suppressors. A composition of clinical, serological, and morphologic features in patients presenting with ILD will fulfill criteria for IPAF. In summary, the early recognition and treatment of CTD-ILD, differentiation from IPF-UIP, and identification of patients with IPAF fulfill the assessment by the clinician for an optimal care.

Occult primary Sjögren Syndrome in patients with interstitial pneumonia with autoimmune features

INTRODUCTION/OBJECTIVES

To define the performance of Minor Salivary Gland Biopsy (MSGB) and Dry Eye Tests (DET) to detect occult Sjögren Syndrome (SS) among Interstitial Pneumonia with Autoimmune Features (IPAF) patients.

METHODS

Prospective study. Interstitial Lung Disease (ILD) patients without defined Connective Tissue Disease and one or more IPAF classification domains or xerophthalmia were included. MSGB, Schirmer's test (ST) and Ocular Staining Score (OSS) were performed in a blinded manner by experienced specialists. MSGB with ≥1 focus of lymphocytes and Dry Eye Test (DET) with OSS ≥ 5 and/or ST < 5 s were considered positive. SS was diagnosed according to the ACR 2016 criteria.

RESULTS

534 patients on the first consult were screened. 67 patients had at least one IPAF criteria, 53 (79.1%) female, mean age (SD) 64.2 years old (10.8). Positive ST in 36 (53.7%), positive OSS in 29 (43.3%) and positive MSGB in 36 (53.7%) were found. Finally, 27 (40.3%) met SS diagnostic criteria. 25 (37.3%) and 18 (26.8%) of them did not report dry eyes or dry mouth, respectively. 53 (79.1%) had negative anti SSA/Ro, 57 (85.1%) had negative anti LA/SSB, 30 (44.7%) had negative ANA, and 52 (77.6%) had negative RF, respectively. A significantly higher proportion of ANA (+), anti-SSA/Ro (+), anti-SSB/La (+), positive DET and positive MSGB were found in the SS population.

CONCLUSIONS

A significant proportion of patients with occult SS were found in our study. MSGB and DET may be considered in the evaluation of IPAF patients.

Transbronchial lung cryobiopsy for connective tissue disease-related interstitial lung disease and interstitial pneumonia with autoimmune features: a single center retrospective case series

OBJECTIVE

Transbronchial lung cryobiopsy (TBLC) has been recently introduced for diagnosing interstitial lung diseases. We aimed to assess the effectiveness and safety of TBLC by identifying the specific patterns of histology in the diagnosis of connective tissue disease-related interstitial lung disease (CTD-ILD) and interstitial pneumonia with autoimmune features (IPAF).

METHODS

The clinical-radiological-pathological data from the Affiliated Hospital of Guilin Medical University between July 1, 2017, and October 31, 2020, of patients whose clinical-radiological or clinical-radiological-pathological diagnosis was CTD-ILD or IPAF and who underwent TBLC, transbronchial lung biopsy (TBLB), or surgical lung biopsy were retrospectively analyzed and summarized with review. The size of biopsy samples, complications, and diagnostic yield were compared.

RESULTS

Fourteen patients met the inclusion criteria, of whom 12 underwent TBLC, 1 underwent TBLB, and 1 underwent each procedure at different times. Compared to the size of TBLB specimens (5.625 ± 0.479 mm²), the size of TBLC specimens (12.00 (12.00, 15.00) mm²) was much larger (Z = - 3.262, P = 0.001). The diagnostic yields of TBLC and TBLB were 100.00% (13/13) and 0.00% (2/2), respectively (P = 0.0095). The most frequent complication was mild bleeding. The risk of bleeding between TBLB (1/2, 50.00%) and TBLC (10/13, 76.92%) did not differ significantly (P = 0.469).

CONCLUSION

TBLC can add extra diagnostic value by effectively identifying specific types of histology for patients with suspected CTD-ILD or IPAF, with a procedure that is safe from adverse events. Key Points • Transbronchial lung cryobiopsy has been introduced recently for diagnosing interstitial lung disease. • Transbronchial lung cryobiopsy was found to be effective and safe in the diagnosis for patients with suspected interstitial lung disease. It can be used as a preferred method for biopsy when the clinical-radiological diagnosis is uncertain.

Interstitial pneumonia with autoimmune features: A case series and overview

The topic of interstitial pneumonia with autoimmune features (IPAF) is a research classification proposed by the European Respiratory Society/American Thoracic Society Task Force: this includes patients with idiopathic interstitial pneumonia (IIP) and clinical features, suggesting an underlying autoimmune process, but who do not meet established criteria for a connective tissue disease (CTD). We aimed to perform a detailed characterization of clinical, serological, and radiological features for our patients with IPAF criteria. Six patients were included, and a comprehensive description of these cases revealed a heterogeneous group in terms of clinical and treatment options. In most patients, it was possible to identify other features and disorders with an autoimmune “background,” which may support the inclusion of these patients in the IPAF classification. No deaths or significant decline in lung function occurred, and thus no definitive diagnosis of CTD could be found over 35 months of median follow-up. Therefore, IPAF is a recent concept, with many questions still open in regard to its usage in the ILD field.

•

IPAF allows to group who presents with IIP and features suggesting an underlying autoimmune process, but do not meet criteria for a CTD.

•

A detailed clinical history is crucial to identify other features or disorders with an autoimmune “background”.

•

Our cases reveal a heterogeneous population, with a “benign” disease behavior, similar to CTD-ILD.

•

The multidisciplinary meeting and follow-up are essential, so that an IPF diagnosis (if UIP pattern is present), or an evolution to CTD-ILD, are not missed.

Serum SP-A and KL-6 levels can predict the improvement and deterioration of patients with interstitial pneumonia with autoimmune features

BACKGROUND

Some patients with interstitial pneumonia with autoimmune features (IPAF) showed a progressive course despite therapy. This study aimed to evaluate whether serial changes in the serum levels of surfactant protein-A (SP-A) and Krebs von den Lungen-6 (KL-6) can predict disease progression.

METHODS

Sixty-four patients with IPAF and 41 patients with non-fibrotic lung disease (non-FLD) were examined. Based on long-term changes in lung function, 36 IPAF patients who were followed up for more than 3 months were divided into a progressive group (n = 9), an improvement group (n = 13), and a stable group (n = 14). Serum KL-6 and SP-A levels were measured. The sensitivity, specificity, cut-off value, and area under the curve (AUC) value for each of the indices were determined using receiver operating characteristic (ROC) curve analysis. The expression differences in these biomarkers and their correlation with disease severity were analyzed.

RESULTS

Compared with non-FLD patients, serum SP-A and KL-6 levels in IPAF patients were increased significantly [SP-A: (p < 0.001); KL-6: (p < 0.001)] and negatively correlated with DLCO (SP-A: r_S = - 0.323, p = 0.018; KL-6: r_S = - 0.348, p = 0.0011). In patients with progressive disease, the posttreatment serum SP-A and KL-6 levels were increased significantly compared with pretreatment levels [SP-A: (p = 0.021); KL-6: (p = 0.008)]. In patients showing improvement, the levels were decreased significantly [SP-A (p = 0.007) and KL-6 (p = 0.002)]. Changes in serum biomarkers (Delta SP-A and Delta KL-6) were significantly negatively correlated with changes in lung function (Delta FVC, Delta DLCO and Delta FEV1) (r_S = 0.482, p < 0.05). A significant positive correlation was found between Delta SP-A and Delta KL-6 (r_S = 0.482, p < 0.001).

CONCLUSIONS

Serum SP-A and KL-6 offer high sensitivity and specificity for the diagnosis of IPAF. The decrease in serum SP-A and/or KL-6 levels in patients with IPAF is related to the improvement in pulmonary function. SP-A and KL-6 may be important biomarkers for predicting disease progression in patients with IPAF.

Connective Tissue Disease Related Interstitial Lung Disease

Patients with connective tissue diseases may have pulmonary involvement, including interstitial lung disease. Various patterns of interstitial lung disease have been classically described in certain connective tissue diseases. It is now recognized that there is significant overlap between patterns of interstitial lung disease observed in the various connective tissue diseases. Differentiating idiopathic from connective tissue disease-related interstitial lung disease is challenging but of clinical importance. New concepts in the diagnosis of connective tissue disease related interstitial lung disease may prove useful in making the diagnosis.

Clinical, radiological, and pathological evaluation of "NSIP with OP overlap" pattern compared with NSIP in patients with idiopathic interstitial pneumonias

BACKGROUND

Nonspecific interstitial pneumonia (NSIP) and organizing pneumonia (OP) are major subtypes of idiopathic interstitial pneumonias (IIPs) and closely related to connective tissue diseases (CTDs). "NSIP with OP overlap" is a controversial finding that has recently appeared in the criteria of interstitial pneumonia with autoimmune features (IPAF). However, details of this controversial entity are not well known.

OBJECTIVE

To determine the frequency of "NSIP with OP overlap" pattern in IIPs and to identify differences from idiopathic NSIP (iNSIP).

METHODS

In 524 patients with interstitial pneumonia from 39 institutes who underwent surgical lung biopsy, 444 were diagnosed as IIPs by a multidisciplinary discussion meeting via a cloud-based integrated database. Among these patients, 44 (9.9%) who had iNSIP and 21 (4.7%) with histopathologically-defined "NSIP with OP overlap" pattern (a pathological NSIP and OP pattern, but without a UIP pattern) were retrospectively studied.

RESULTS

Patients with "NSIP with OP overlap" pattern showed a significantly greater extent of consolidation (p < 0.001), more subpleural ground glass attenuation (p = 0.036), and more peripheral + bronchovascular distribution (p = 0.009) on high-resolution computed tomography than those with iNSIP. The incidences of newly-developed CTDs during follow-up was similar between the groups and polymyositis/dermatomyositis was the most frequent CTD in both groups. Nearly half of the patients fulfilled IPAF criteria, but no significant difference was found between iNSIP and "NSIP with OP overlap" pattern (47.7% vs. 42.9, p = 0.712). The incidence of acute exacerbation and the survival rates were similar between the groups.

CONCLUSIONS

The incidence of "NSIP with OP overlap" pattern is 4.7% in IIPs. The frequency of newly-developed CTDs during follow-up, mainly polymyositis/dermatomyositis, the frequency of acute exacerbation, and the survival rate in "NSIP with OP overlap" pattern are similar to those of iNSIP.

IPAF should receive early treatment for sharing similar clinical characteristics as CTD-ILD: a report from 273 Chinese patients

OBJECTIVES

The clinical characteristics of interstitial pneumonia with autoimmune features (IPAF) and connective tissue disease interstitial lung disease (CTD-ILD) have not been adequately compared. We compared the clinical characteristics of these two conditions and analyzed the changes in lung function before and after treatment of IPAF.

METHODS

A total of 412 patients were enrolled in the study, and their clinical characteristics were assessed. The treatment-related changes in 12 cases of IPAF were analyzed.

RESULTS

Complete clinical data were available for 126 patients with CTD-ILD and 147 with IPAF. All IPAF patients showed autoantibody positivity. The proportion of patients showing extrapulmonary symptoms in the CTD-ILD group was higher than that in the IPAF group (P < 0.05). Patients with IPAF demonstrated lower P(A-a)O₂ and higher PaO₂ and PaCO₂ than those with CTD-ILD (P < 0.05 for all comparisons). Forced vital capacity (FVC) and diffusing capacity of the lungs for carbon monoxide (D_LCO) in IPAF patients were higher than those in CTD-ILD patients (P = 0.023 for FVC; P = 0.011 for D_LCO). Among patients with IPAF, only the proportions of honeycombing and nodules were lower than those in CTD-ILD patients (P < 0.05). Both FVC and D_LCO values increased after treatment in patients with IPAF (P < 0.05).

CONCLUSION

IPAF showed autoantibody positivity and similar computed tomography (CT) findings as CTD-ILD, and lung function in patients with IPAF improved after immunosuppressive treatment, indicating that IPAF should receive attention and early immunosuppressive treatment like CTD-ILD, even though IPAF exhibits no extrapulmonary symptoms. Key Points • Clinical characteristics of IPAF.

Systematic review and meta-analysis of the prognosis and prognostic factors of interstitial pneumonia with autoimmune features

OBJECTIVE

To clarify the prognosis and prognostic factors of interstitial pneumonia with autoimmune features (IPAF) in comparison to idiopathic pulmonary fibrosis (IPF), the most common idiopathic interstitial pneumonia, and connective tissue disease-associated interstitial pneumonia (CTD-IP).

DESIGN

A systematic review and meta-analysis.

DATA SOURCES

Electronic databases such as Medline and Embase were searched from 2015 through 6 September 2019.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Primary studies that comparatively investigated the prognosis or prognostic factors of IPAF were eligible.

DATA EXTRACTION AND ANALYSIS

Two reviewers extracted relevant data and assessed the risk of bias independently. A meta-analysis was conducted using a random-effects model. The quality of presented evidence was assessed by the Grades of Recommendation, Assessment, Development, and Evaluation system.

RESULTS

Out of a total of 656 records retrieved, 12 studies were reviewed. The clinical features of IPAF were diverse between studies, which included a radiological and/or pathological usual interstitial pneumonia (UIP) pattern of between 0% and 73.8%. All studies contained some risk of bias. There was no significant difference of all-cause mortality between IPAF-UIP and IPF in all studies, although the prognosis of IPAF in contrast to IPF or CTD-IP varied between studies depending on the proportion of UIP pattern. Among the potential prognostic factors identified, age was significantly associated with all-cause mortality of IPAF by a pooled analysis of univariate results with a hazard ratio (HR) of 1.06 (95% confidence interval (CI) 1.04 to 1.07). The adjusted effect of age was also significant in all studies. The quality of presented evidence was deemed as very low.

CONCLUSION

There was no significant difference of all-cause mortality between IPAF-UIP and IPF. Age was deemed as a prognostic factor for all-cause mortality of IPAF. The findings should be interpreted cautiously due to the low quality of the presented evidence.

PROSPERO REGISTRATION NUMBER

CRD42018115870.

Comparative analysis of connective tissue disease-associated interstitial lung disease and interstitial pneumonia with autoimmune features

OBJECTIVE

This retrospective clinical study aimed to examine the similarities and differences between connective tissue disease-associated interstitial lung disease (CTD-ILD) and interstitial pneumonia with autoimmune features (IPAF) and to identify the influencing factors of CTD-ILD, with a goal of early detection and active treatment of the disease.

METHODS

We conducted a retrospective study of 480 patients: 412 with CTD-ILD and 68 with IPAF. Demographic features, clinical characteristics, laboratory indicators, and chest high-resolution computed tomography (HRCT) imaging data were analyzed.

RESULTS

Compared with the IPAF group, the CTD-ILD group contained more women, and the incidences of joint pain, dry mouth/dry eyes, and Raynaud's phenomenon were higher; erythrocyte sedimentation rate (ESR) and D-dimer levels were higher; red blood cell (RBC) and hemoglobin (Hb) levels were lower; a high rheumatoid factor (RF) titer (> 2 times the normal upper limit) was observed, and anti-cyclic citrullinated peptide antibody (anti-CCP), anti-keratin antibody (AKA), antinuclear antibody (ANA), and anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5) levels were higher. Compared with CTD-ILD patients, IPAF patients were more likely to present initially with respiratory symptoms, with higher rates of fever, cough and expectoration, dyspnea, and Velcro crackles; anti-Ro52 titers were higher; incidences of honeycombing opacity, reticulate opacity, patchy opacity, and pleural thickening were greater. Female sex, a high RF titer (> 2 times the normal upper limit), anti-CCP positivity, ANA positivity, and anti-MDA5 positivity were risk factors for CTD-ILD when the odds ratios were adjusted.

CONCLUSION

CTD-ILD and IPAF patients differed in demographic features, clinical characteristics, laboratory indicators, and chest HRCT imaging data. Female sex, a high RF titer (> 2 times the normal upper limit), anti-CCP positivity, ANA positivity, and anti-MDA5 positivity were risk factors for CTD-ILD.Key Points• This retrospective clinical study comprehensively compared the demographic features, clinical characteristics, laboratory indicators, and chest HRCT imaging data of CTD-ILD and IPAF patients.• The evidence suggested that female sex, a high RF titer, anti-CCP positivity, ANA positivity, and anti-MDA5 positivity were risk factors for CTD-ILD.

Presentations and outcomes of interstitial lung disease and the anti-Ro52 autoantibody

Background

Distinct clinical presentations of interstitial lung disease (ILD) with the myositis-specific antibodies, including anti-synthetase antibodies, are well-recognized. However, the association between ILD and the myositis-associated antibodies, including anti-Ro52, is less established. Our objectives were to compare presenting phenotypes of patients with anti-Ro52 alone versus in combination with myositis-specific autoantibodies and to identify predictors of disease progression or death.

Methods

We performed a retrospective cohort study of 73 adults with ILD and a positive anti-Ro52 antibody. We report clinical features, treatment, and outcomes.

Results

The majority of patients with ILD and anti-Ro52 had no established connective tissue disease (78%), and one-third had no rheumatologic symptoms. Thirteen patients (17.8%) required ICU admission for respiratory failure, with 84.6% all-cause mortality. Of the 73 subjects, 85.7% had a negative SS-A, and 49.3% met criteria for idiopathic pneumonia with autoimmune features (IPAF). The 50 patients with anti-Ro52 alone were indistinguishable from patients with anti-Ro52 plus a myositis-specific autoantibody. ICU admission was associated with poor outcomes (HR 12.97, 95% CI 5.07–34.0, p < 0.0001), whereas rheumatologic symptoms or ANA > = 1:320 were associated with better outcomes (HR 0.4, 95% CI 0.16–0.97, p = 0.04, and HR 0.29, 95% CI 0.09–0.81, p = 0.03, respectively).

Conclusions

Presentations of ILD with the anti-Ro52 antibody are heterogeneous, and outcomes are similar when compared to anti-Ro52 plus myositis-specific antibodies. Testing for anti-Ro52 may help to phenotype unclassifiable ILD patients, particularly as part of the serologic criteria for IPAF. Further research is needed to investigate treatment of ILD in the setting of anti-Ro52 positivity.

Imaging of the Thoracic Manifestations of Connective Tissue Disease

Imaging, specifically computed tomography (CT), is a key component in the characterization, management, and follow-up of patients with connective tissue disease (CTD)-related diffuse lung disease. The main role of CT is to help direct treatment by determining the primary pattern of lung injury present. Other roles include follow-up of lung disease over time, evaluation of acute symptoms, and monitoring for treatment complications. Although diagnosis is typically made using clinical and serologic criteria, CT plays an important role when lung disease is the dominant presenting feature. This article delineates the roles of CT in patients with CTD-related lung disease.

Interstitial pneumonia with autoimmune features show better survival and less exacerbations compared to idiopathic pulmonary fibrosis

BACKGROUND

Patients with interstitial lung disease (ILD) who show features related to autoimmunity without meeting criteria for a defined connective tissue disease are categorized as interstitial pneumonia with autoimmune features (IPAF). The present study compared clinical characteristics and clinical outcomes of patients with IPAF to patients with connective tissue disease related-interstitial lung disease (CTD-ILD) and patients with idiopathic pulmonary fibrosis (IPF).

METHODS

ILD patients who were consecutively enrolled in a single institution ILD cohort between 2008 and 2015 were evaluated for the study. Clinical data had been prospectively collected, while radiologic imaging and pathologic findings were re-reviewed for the present study.

RESULTS

Out of 305 patients with ILD, 54 (17.7%) patients met the classification of IPAF, 175 (57.4%) patients had IPF, and 76 (24.9%) patients were diagnosed with CTD-ILD. Compared to IPF, incidences of acute exacerbations in 1,3 and 5 years were significantly less in the IPAF group (p = 0.022, p = 0.026 and p = 0.007, respectively). From multivariate analysis for mortality, age (p = 0.034, HR 1.022, 95% CI: 1.002-1.044), FVC (p < 0.001, HR 0.970, 95% CI: 0.955-0.984), ILD exacerbation (p = 0.001, HR 2.074, 95% CI: 1.366-3.148), and ILD type (p = 0.047, HR 0.436, 95% CI: 0.192-0.984 (IPAF vs IPF), respectively) showed significant association.

CONCLUSIONS

Compared to the other ILD groups, IPAF showed distinct clinical characteristics. The IPAF group showed better survival and less episodes of exacerbation when compared to the IPF group.

Contribution of pulmonary function tests (PFTs) to the diagnosis and follow up of connective tissue diseases

Introduction

Connective Tissue Diseases (CTDs) are systemic autoimmune conditions characterized by frequent lung involvement. This usually takes the form of Interstitial Lung Disease (ILD), but Obstructive Lung Disease (OLD) and Pulmonary Artery Hypertension (PAH) can also occur. Lung involvement is often severe, representing the first cause of death in CTD. The aim of this study is to highlight the role of Pulmonary Function Tests (PFTs) in the diagnosis and follow up of CTD patients.

Main body

Rheumatoid Arthritis (RA) showed mainly an ILD with a Usual Interstitial Pneumonia (UIP) pattern in High-Resolution Chest Tomography (HRCT). PFTs are able to highlight a RA-ILD before its clinical onset and to drive follow up of patients with Forced Vital Capacity (FVC) and Carbon Monoxide Diffusing Capacity (DL_CO). In the course of Scleroderma Spectrum Disorders (SSDs) and Idiopathic Inflammatory Myopathies (IIMs), DL_CO appears to be more sensitive than FVC in highlighting an ILD, but it can be compromised by the presence of PAH. A restrictive respiratory pattern can be present in IIMs and Systemic Lupus Erythematosus due to the inflammatory involvement of respiratory muscles, the presence of fatigue or diaphragm distress.

Conclusions

The lung should be carefully studied during CTDs. PFTs can represent an important prognostic tool for diagnosis and follow up of RA-ILD, but, on their own, lack sufficient specificity or sensitivity to describe lung involvement in SSDs and IIMs. Several composite indexes potentially able to describe the evolution of lung damage and response to treatment in SSDs are under investigation. Considering the potential severity of these conditions, an HRCT jointly with PFTs should be performed in all new diagnoses of SSDs and IIMs. Moreover, follow up PFTs should be interpreted in the light of the risk factor for respiratory disease related to each disease.

Interstitial Lung Disease in patients with Polymyalgia Rheumatica: A case series

Introduction

Severe morning stiffness with painful involvement of the girdles are often referred by patients with Interstitial Lung Disease (ILD), but the association between ILD and Polymyalgia Rheumatica (PMR) is rarely reported. The purpose of the work is to describe a series of patients classified as having PMR with ILD.

Material and methods

We retrospectively enrolled patients with a diagnosis of PMR referred to our center during the previous year for respiratory symptoms. Data concerning clinical and serological manifestations suggesting Connective Tissue Disease (CTD), High-Resolution Chest Tomography (HRCT), and Pulmonary Function Tests (PFTs) were systematically collected in order to verify the diagnosis.

Results

Fifteen out of seventeen PMR patients had ILD. Ten patients had a confirmed diagnosis of PMR, while in five patients a CTD was discovered. Seven patients showed a severe restrictive pattern at PFTs requiring oxygen supplementation (five with PMR and two with CTD). In thirteen patients pulmonary symptoms started before or together with muscular symptoms. Regarding HRCT patterns, patients showed a Nonspecific Interstitial Pneumonia in nine cases, Usual Interstitial Pneumonia (UIP) and possible UIP in two and three cases, and a single case of Organizing Pneumonia and Combined Pulmonary Fibrosis and Emphysema Syndrome.

Conclusions

Lung involvement should be evaluated in PMR patients, especially if asthenia is poorly responsive to low doses of steroids. In these cases, the diagnosis should be re-evaluated in depth, looking for a seronegative Rheumatoid Arthritis, a clinically amyopathic myositis or Interstitial Pneumonia with Autoimmune features.

Clinical features, risk factors, and outcomes of patients with interstitial pneumonia with autoimmune features: a population-based study

To investigate the clinical features, risk factors and outcomes of patients with interstitial pneumonia with autoimmune features (IPAF). A total of 1429 patients with idiopathic interstitial pneumonia (IIP) and undifferentiated connective tissue disease-associated interstitial lung disease (UCTD-ILD) were screened to identify patients who met IPAF criteria. Clinical, serological, and morphological features of patients with IPAF were characterized. Outcomes between patients with IPAF, UCTD-ILD, and IIP who were divided into idiopathic pulmonary fibrosis (IPF) and non-IPF groups were compared using survival as an endpoint. Patients with IPAF were much common in young female and had lower percentage of ever smoking and a significantly shorter survival than those with non-IPAF (P < 0.001). Subgroup analysis revealed that IPAF cohort survival was worse than that in non-IPF (P < 0.001), but better than that in IPF (P < 0.001). In IPAF cohort, the most common systemic symptom and serological abnormality were Raynaud's phenomenon (12.9%) and ANA ≥ 1:320 (49.2%); the most frequent high-resolution computed tomography (HRCT) pattern was nonspecific interstitial pneumonia (NSIP) (61.6%). Multivariate analysis indicated that several factors including age, smoking history, organizing pneumonia (OP) pattern in HRCT, and anti-RNP positivity were independently associated with significantly worse survival. IPAF had the distinct clinical features and outcomes compared with other groups of ILD. Additional studies should be needed to explore the underlying autoimmune mechanism and to determine risk stratification in future clinical research.

N-acetylcysteine exposure is associated with improved survival in anti-nuclear antibody seropositive patients with usual interstitial pneumonia

Background

Mortality is similarly high among individuals with usual interstitial pneumonia (UIP) due to idiopathic pulmonary fibrosis (IPF) and interstitial pneumonia with autoimmune features (IPAF). Circulating anti-nuclear antibodies (ANA) are commonly found in this patient population, suggesting possible aberrant immune activation. Because an environment of oxidative stress can result from immunologic activation, we hypothesized that ANA positive patients with UIP would have improved outcome when exposed to the antioxidant N-acetylcysteine (NAC) compared to ANA negative patients.

Methods

A single center, retrospective cohort analysis was performed. Patients with UIP due to IPF and IPAF were stratified according to ANA status to and NAC exposure. Transplant-free survival (TFS) was assessed using the Kaplan-Meier estimator and multivariable Cox regression adjusted for diagnosis, gender/age/physiology score, immunosuppressant exposure and anti-fibrotic exposure.

Results

Of 293 individuals with UIP due to IPF (74%) or IPAF (26%), NAC exposure was documented in 58 (19.8%). Among NAC exposed individuals, 33 (56.9%) were ANA seropositive and 25 (43.1%) were seronegative. NAC exposure was associated with improved TFS survival among ANA seropositive individuals in unadjusted analysis (p_logrank = 0.02) and after multi-variable adjustment (HR 0.51, 95% CI 0.30–0.87; p = 0.01). There was no association between NAC exposure and TFS in ANA seronegative individuals (HR 1.26, 95% CI 0.69–2.32; p = 0.45). Formal interaction testing confirmed NAC*ANA interaction (p = 0.04) and sensitivity analysis demonstrated an increasing effect size associated with NAC therapy as ANA titer increased. Among patients with available genetic data, a marginally higher proportion of ANA positive patients (p = 0.08) carried the rs3750920 (TOLLIP) genotype previously shown to predict favorable outcome in NAC exposed patients.

Conclusion

NAC exposure is associated with improved transplant-free survival ANA positive patients with UIP. These findings support the prospective collection of ANA data in in future NAC clinical trials performed in patients with UIP.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0599-3) contains supplementary material, which is available to authorized users.

Clinico-radio-pathological characteristics of unclassifiable idiopathic interstitial pneumonias

BACKGROUND

The purpose of this study was to clarify the clinico-radio-pathological characteristics and prognostic factors of unclassifiable-idiopathic interstitial pneumonias (U-IIPs) diagnosed by surgical lung biopsy.

METHODS

Among 86 patients with interstitial pneumonia who underwent surgical lung biopsy from January 2005 to September 2013, 33 (38.4%; 16 male patients; mean age, 64.4 ± 8.8 years) were diagnosed with U-IIPs. They were subsequently categorized into rapidly progressive (n = 7), slowly progressive (n = 7), and stable (n = 19) groups based on the decrease of the percent predicted forced vital capacity or percent predicted diffusing capacity of the lung carbon monoxide and the occurrence of acute exacerbation. The clinico-radio-pathological features and survival rates of the patients who were followed up for at least 3 years were examined. These cases were reevaluated retrospectively by multidisciplinary discussion.

RESULTS

The rapidly progressive group had a significantly poorer prognosis than that of the other groups (p < 0.0001). Although there were no significant pattern differences on the chest high-resolution computed tomography, the fibrosis scores were significantly higher in the rapidly progressive group (p = 0.002). Furthermore, the percentage of fibroblastic foci assessed by the pathological analysis was also significantly higher in the rapidly progressive group (p = 0.006). Nine (27.3%) patients developed connective tissue diseases during follow-up.

CONCLUSIONS

The radiologic patterns were not significantly different among the three clinical U-IIPs subgroups. Nevertheless, our findings suggested that the fibrosis scores and the percentage of fibroblastic foci could provide a prognostic assessment in U-IIPs.

Interstitial pneumonia with autoimmune features: an additional risk factor for ARDS?

Background

Interstitial pneumonia with autoimmune features (IPAF) identifies a recently recognized autoimmune syndrome characterized by interstitial lung disease and autoantibodies positivity, but absence of a specific connective tissue disease diagnosis or alternative etiology. We retrospectively reviewed the clinical presentation, diagnostic workup and management of seven critically ill patients who met diagnostic criteria for IPAF. We compared baseline characteristics and clinical outcome of IPAF patients with those of the population of ARDS patients admitted in the same period.

Results

Seven consecutive patients with IPAF admitted to intensive care unit for acute respiratory distress syndrome (ARDS) were compared with 78 patients with ARDS secondary to a known risk factor and with eight ARDS patients without recognized risk factors. Five IPAF patients (71%) survived and were discharged alive from ICU: Their survival rate was equal to that of patients with a known risk factor (71%), while the subgroup of patients without risk factors had a markedly lower survival (38%). According to the Berlin definition criteria, ARDS was severe in four IPAF patients and moderate in the remaining three. All had multiple organ dysfunction at presentation. The most frequent autoantibody detected was anti-SSA/Ro52. All patients required prolonged mechanical ventilation (median duration 49 days, range 10–88); four received extracorporeal membrane oxygenation and one received low-flow extracorporeal CO₂ removal. All patients received immunosuppressive therapy.

Conclusions

This is the first description of a cohort of critical patients meeting the diagnostic criteria for IPAF presenting with ARDS. This diagnosis should be considered in any critically ill patient with interstitial lung disease of unknown origin. While management is challenging and level of support high, survival appears to be good and comparable to that of patients with ARDS associated with a known clinical insult

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-017-0320-3) contains supplementary material, which is available to authorized users.

Serological and morphological prognostic factors in patients with interstitial pneumonia with autoimmune features

Background

To identify the prognostic factors for survival in patients with interstitial pneumonia with autoimmune features (IPAF) who meet the serological domain of the IPAF criteria.

Methods

We retrospectively analysed 99 IPAF patients who met the serological domain and were hospitalised at the Respiratory Medicine Unit of Kurashiki Central Hospital from 1999 to 2015. The high-resolution computed tomography findings were usual interstitial pneumonia (UIP; n = 1), non-specific interstitial pneumonia (NSIP; n = 63), NSIP with organizing pneumonia (OP) overlap (n = 15), and OP (n = 20). One patient who had radiological UIP pattern, and met the serological and clinical domains was excluded. The clinical characteristics, radiological findings, administered therapy, and prognosis of the remaining 98 IPAF patients who met the serological and morphological domains were analysed.

Results

The median age of the 98 IPAF patients was 68 years, and 41 (41.8%) of them were men. Twelve (12.2%) of the 98 IPAF patients developed other characteristics and were diagnosed with connective tissue disease (CTD) later during the median follow-up of 4.5 years. Univariate Cox analysis revealed systemic sclerosis (SSc)-specific and SSc-associated antibodies (ANA nucleolar pattern, ANA centromere pattern, anti-ribonucleoprotein and anti-Scl-70) positive IPAF, radiological NSIP pattern, bronchoalveolar lavage fluid lymphocytes >15%, and age as significant prognostic factors for survival. Multivariate Cox analysis revealed radiological NSIP pattern (hazard ratio [HR], 4.48; 95% confidence interval [CI], 1.28–15.77, p = 0.02) and age (HR, 1.07; 95% CI, 1.02–1.11, p = 0.01) were significantly associated with worse survival.

Conclusions

We confirmed that radiological NSIP pattern and age are poor prognostic factors for the survival of IPAF patients. This study suggested that the autoantibodies that are highly specific for certain connective tissue diseases might be less important for the prognosis of IPAF compared with the radiological-pathological patterns. The relatively high proportion of IPAF patients who developed CTD later suggests the importance of careful observation for evolution to CTD in IPAF.