Successful Treatment of Shrinking Lung Syndrome With Rituximab in a Patient With Systemic Lupus Erythematosus

Systemic Lupus Erythematosus and Lung Involvement: A Comprehensive Review

Systemic lupus erythematosus (SLE) is a complex autoimmune disease with multiorgan manifestations, including pleuropulmonary involvement (20-90%). The precise mechanism of pleuropulmonary involvement in SLE is not well-understood; however, systemic type 1 interferons, circulating immune complexes, and neutrophils seem to play essential roles. There are eight types of pleuropulmonary involvement: lupus pleuritis, pleural effusion, acute lupus pneumonitis, shrinking lung syndrome, interstitial lung disease, diffuse alveolar hemorrhage (DAH), pulmonary arterial hypertension, and pulmonary embolism. DAH has a high mortality rate (68-75%). The diagnostic tools for pleuropulmonary involvement in SLE include chest X-ray (CXR), computed tomography (CT), pulmonary function tests (PFT), bronchoalveolar lavage, biopsy, technetium-99m hexamethylprophylene amine oxime perfusion scan, and (18)F-fluorodeoxyglucose positron emission tomography. An approach for detecting pleuropulmonary involvement in SLE includes high-resolution CT, CXR, and PFT. Little is known about specific therapies for pleuropulmonary involvement in SLE. However, immunosuppressive therapies such as corticosteroids and cyclophosphamide are generally used. Rituximab has also been successfully used in three of the eight pleuropulmonary involvement forms: lupus pleuritis, acute lupus pneumonitis, and shrinking lung syndrome. Pleuropulmonary manifestations are part of the clinical criteria for SLE diagnosis. However, no review article has focused on the involvement of pleuropulmonary disease in SLE. Therefore, this article summarizes the literature on the epidemiology, pathogenesis, diagnosis, and management of pleuropulmonary involvement in SLE.

Shrinking Lung Syndrome: A Case Report

Shrinking Lung Syndrome (SLS) is an uncommon complication of systemic lupus erythematosus (SLE). SLS is a diagnosis of exclusion with features of dyspnea ruled out by other causes using imaging and diagnostic studies, pleuritic chest pain, and elevated diaphragm. Currently, there are many theories of the etiology; however, there is no clear pathogenesis, conclusive treatment, and preventative measures. We report a case of a 41-year-old woman with SLE admitted for pleuritic chest pain with unclear cause of shortness of breath. After CTA chest study, laboratory, chest x-ray, and pulmonary function test we were able to appropriately diagnose her with SLS and treat her with steroids as per limited current research guidelines.

Treating Autoimmune-Related Interstitial Lung Disease With B Cell Depletion

Autoimmune rheumatic diseases may affect vital organs with lung involvement being severe and difficult to treat manifestation. Systemic sclerosis (SSc) commonly affects the lung in the form of interstitial lung disease (ILD). ILD may be also seen in patients with rheumatoid arthritis (RA), Sjögren's syndrome (SS), systemic lupus erythematosus (SLE), inflammatory myositis (IM), antisynthetase syndrome (AS), and the ANCA-associated vasculitides (AAV). Rituximab (RTX) is an anti-CD20 B lymphocyte depleting mAb, often administered in the treatment of autoimmune rheumatic diseases. Although RTX is an off-label treatment for CTD–ILD, there are numerous reports providing data that is effective in improving both pulmonary function tests (PFTs) and chest computed tomography findings consistent with ILD. There are retrospective uncontrolled studies that assess RTX as a treatment of ILD in autoimmune diseases. These studies, apart from one, do not include patients with AAV-ILD. In SSc-ILD, in particular, there are both controlled and uncontrolled studies displaying encouraging results following B cell depletion. In addition, a number of retrospective uncontrolled studies and fewer prospective studies evaluate RTX in connective tissue diseases CTD–ILD. Although RTX is an approved treatment for AAV there are scarce only data focusing on patients with AAV-ILD specifically. The results of a handful of studies comparing treatment of CTD-ILD with RTX to treatment with other agents are in favor of RTX. Results from large, still ongoing controlled trials are awaited to ascertain RTX effects in ILD encountered in autoimmune rheumatic diseases. We review herein the results of the different RTX trials in patients with autoimmune disease–associated with ILD. Despite the heterogeneity of these studies, RTX may be considered an alternative and safe but still off-label treatment for patients with refractory CTD–ILD.

Myositis with prominent B-cell aggregates causing shrinking lung syndrome in systemic lupus erythematosus: a case report

BACKGROUND

Shrinking lung syndrome (SLS) is a rare manifestation of systemic lupus erythematosus (SLE) characterized by decreased lung volumes and diaphragmatic weakness in a dyspneic patient. Chest wall dysfunction secondary to pleuritis is the most commonly proposed cause. In this case report, we highlight a new potential mechanism of SLS in SLE, namely diaphragmatic weakness associated with myositis with CD20 positive B-cell aggregates.

CASE PRESENTATION

A 51-year-old Caucasian woman was diagnosed with SLE and secondary Sjögren's syndrome based on a history of pleuritis, constrictive pericarditis, polyarthritis, photosensitivity, alopecia, oral ulcers, xerophthalmia and xerostomia. Serologies were significant for positive antinuclear antibodies, anti-SSA, lupus anticoagulant and anti-cardiolopin. Blood work revealed a low C3 and C4, lymphopenia and thrombocytopenia. She was treated with with low-dose prednisone and remained in remission with oral hydroxychloroquine. Seven years later, she developed mild proximal muscle weakness and exertional dyspnea. Pulmonary function testing revealed a restrictive pattern with small lung volumes. Pulmonary imaging showed elevation of the right hemidiaphragm without evidence of interstitial lung disease. Diaphragmatic ultrasound was suggestive of profound diaphragmatic weakness and dysfunction. Based on these findings, a diagnosis of SLS was made. Her proximal muscle weakness was investigated, and creatine kinase (CK) levels were normal. Electromyography revealed fibrillation potentials in the biceps, iliopsoas, cervical and thoracic paraspinal muscles, and complex repetitive discharges in cervical paraspinal muscles. Biceps muscle biopsy revealed dense endomysial lymphocytic aggregates rich in CD20 positive B cells, perimysial fragmentation with plasma cell-rich perivascular infiltrates, diffuse sarcolemmal upregulation of class I MHC, perifascicular upregulation of class II MHC, and focal sarcolemmal deposition of C5b-9. Treatment with prednisone 15 mg/day and oral mycophenolate mofetil 2 g/day was initiated. Shortness of breath and proximal muscle weakness improved significantly.

CONCLUSION

Diaphragmatic weakness was the inaugural manifestation of myositis in this patient with SLE. The spectrum of myologic manifestations of myositis with prominent CD20 positive B-cell aggregates in SLE now includes normal CK levels and diaphragmatic involvement, in association with SLS.

Diagnosis and management of lung involvement in systemic lupus erythematosus and Sjögren's syndrome: a literature review

Lung involvement in systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS) has extensively been outlined with a multiplicity of different manifestations. In SLE, the most frequent finding is pleural effusion, while in pSS, airway disease and parenchymal disorders prevail. In both cases, there is an increased risk of pre-capillary and post-capillary pulmonary arterial hypertension (PAH) and pulmonary venous thromboembolism (VTE). The risk of VTE is in part due to an increased thrombophilic status secondary to systemic inflammation or to the well-established association with antiphospholipid antibody syndrome (APS). The lung can also be the site of an organ-specific complication due to the aberrant pathologic immune-hyperactivation as occurs in the development of lymphoma or amyloidosis in pSS. Respiratory infections are a major issue to be addressed when approaching the differential diagnosis, and their exclusion is required to safely start an immunosuppressive therapy. Treatment strategy is mainly based on glucocorticoids (GCs) and immunosuppressants, with a variable response according to the primary pathologic process. Anticoagulation is recommended in case of VTE and multi-targeted treatment regimens including different drugs are the mainstay for PAH management. Antibiotics and respiratory physiotherapy can be considered relevant complement therapeutic measures. In this article, we reviewed lung manifestations in SLE and pSS with the aim to provide a comprehensive overview of their diagnosis and management to physicians taking care of patients with connective tissue diseases.

Respiratory Manifestations in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease characterized by a wide spectrum of clinical manifestations. The respiratory system can be involved in up to 50-70% of patients and be the presenting manifestation of the disease in 4-5% of cases. Every part of the respiratory part can be involved, and the severity can vary from mild self-limiting to life threatening forms. Respiratory involvement can be primary (caused by SLE itself) or secondary (e.g., infections or drug toxicity), acute or chronic. The course, treatment and prognosis vary greatly depending on the specific pattern of the disease. This review article aims at providing an overview of respiratory manifestations in SLE along with an update about therapeutic approaches including novel biologic therapies.

Lupus and the Lungs: The Assessment and Management of Pulmonary Manifestations of Systemic Lupus Erythematosus

Pulmonary manifestations of systemic lupus erythematosus (SLE) are wide-ranging and debilitating in nature. Previous studies suggest that anywhere between 20 and 90% of patients with SLE will be troubled by some form of respiratory involvement throughout the course of their disease. This can include disorders of the lung parenchyma (such as interstitial lung disease and acute pneumonitis), pleura (resulting in pleurisy and pleural effusion), and pulmonary vasculature [including pulmonary arterial hypertension (PAH), pulmonary embolic disease, and pulmonary vasculitis], whilst shrinking lung syndrome is a rare complication of the disease. Furthermore, the risks of respiratory infection (which often mimic acute pulmonary manifestations of SLE) are increased by the immunosuppressive treatment that is routinely used in the management of lupus. Although these conditions commonly present with a combination of dyspnea, cough and chest pain, it is important to consider that some patients may be asymptomatic with the only suggestion of the respiratory disorder being found incidentally on thoracic imaging or pulmonary function tests. Treatment decisions are often based upon evidence from case reports or small cases series given the paucity of clinical trial data specifically focused on pulmonary manifestations of SLE. Many therapeutic options are often initiated based on studies in severe manifestations of SLE affecting other organ systems or from experience drawn from the use of these therapeutics in the pulmonary manifestations of other systemic autoimmune rheumatic diseases. In this review, we describe the key features of the pulmonary manifestations of SLE and approaches to investigation and management in clinical practice.

Shrinking lung syndrome treated with rituximab in pediatric systemic lupus erythematosus: a case report and review of the literature

BACKGROUND

Shrinking lung syndrome (SLS), a rare complication of systemic lupus erythematosus (SLE) characterized by dyspnea, low lung volumes, and a restrictive pattern on pulmonary function tests (PFTs), has only been reported in a few children. Given the rarity of SLS there is a paucity of literature regarding its optimal treatment. Outcomes are variable, with case reports documenting some improvement in most patients treated with corticosteroids, with or without additional immunosuppressive agents. However, most reported patients did not recover normal lung function. We report full recovery of a child with SLE and SLS following treatment with rituximab and review the current literature.

CASE PRESENTATION

An 11-year-old boy presented with a malar rash, myositis, arthritis, oral ulcers, leukopenia, anemia, positive lupus autoantibodies and Class II nephritis. He was diagnosed with SLE and treated with corticosteroids, hydroxychloroquine, azathioprine, and subsequently mycophenolate with symptom resolution. At age 14, his SLE flared coincident with a viral chest infection. He presented with a malar rash, polyarthritis, increased proteinuria and pleuritis which all improved with corticosteroids and ongoing treatment with mycophenolate. Six weeks later he presented with severe dyspnea, markedly decreased lung volumes, but otherwise normal chest X-ray (CXR) and high-resolution chest computed tomography (HRCT). He was found to have severely restricted PFTs (FEV1 27%, FVC 29%; TLC 43%). After additional investigations including echocardiography, pulmonary CT angiography, and diaphragmatic fluoroscopy, he was diagnosed with SLS and treated with rituximab and methylprednisolone. At 1 month his symptoms had improved, but he still had dyspnea with exertion and severely restricted PFTs. At 6 months his FVC and TLC had improved to 51 and 57% respectively, and were 83 and 94% respectively at 4 years. He had returned to all baseline activities, including competitive hockey.

CONCLUSIONS

Although extremely rare, it is important to recognize SLS as a possible cause of dyspnea and chest pain in a child with SLE. Optimal treatment strategies are unknown. This is the second reported case of a child treated with rituximab for SLS who recovered normal lung function. International lupus registries should carefully document the occurrence, treatment and outcome of patients with SLS to help determine the optimal treatment for this rare complication.

Detection of serum MCP-1 and TGF-β1 in polymyositis/dermatomyositis patients and its significance

OBJECTIVE

This study aims to detect serum levels of monocyte chemoattractant protein-1 (MPC-1) and transforming growth factor-β1 (TGF-β1) in polymyositis/dermatomyositis (PM/DM) patients complicated with interstitial lung disease (ILD), to reveal the significance of the changes in these levels in the pathogenesis of PM/DM complicated with ILD.

METHODS

Serum MCP-1 and TGF-β1 levels in PM/DM patients complicated with ILD, patients with pulmonary infections and normal controls (n = 30, each) were detected using enzyme-linked immunosorbent assay (ELISA), and the correlation between PM/DM complicated with ILD and serum MCP-1 and TGF-β1 levels was analyzed.

RESULTS

Serum MCP-1 and TGF-β1 levels were both higher in PM/DM patients complicated with ILD compared with patients with pulmonary infections and normal controls.

CONCLUSION

Serum MCP-1 and TGF-β1 levels increased in PM/DM patients, and were closely correlated to the complication of ILD. This finding can be used for distinguishing between pulmonary infections and ILD, providing a new diagnostic method for the early prediction of DM/PM complicated with ILD.

Shrinking lung syndrome and systemic lupus erythematosus: a case series and literature review

Shrinking lung syndrome (SLS) is a rare manifestation of systemic lupus erythematosus, characterized by progressive dsypnoea, reduced lung volumes and associated restrictive lung physiology. Here, we provide two previously unreported cases, and review the available literature on the pathophysiology, clinical features and management of SLS. Effective treatment can prevent further deterioration or lead to improvement in abnormal lung function. A heightened awareness of SLS and its management is therefore required to prevent disease progression and increased morbidity.

Diaphragm Dysfunction: Diagnostic Approaches and Management Strategies

The diaphragm is the main inspiratory muscle, and its dysfunction can lead to significant adverse clinical consequences. The aim of this review is to provide clinicians with an overview of the main causes of uni- and bi-lateral diaphragm dysfunction, explore the clinical and physiological consequences of the disease on lung function, exercise physiology and sleep and review the available diagnostic tools used in the evaluation of diaphragm function. A particular emphasis is placed on the clinical significance of diaphragm weakness in the intensive care unit setting and the use of ultrasound to evaluate diaphragmatic action.

Shrinking lung syndrome in systemic lupus erythematosus: A case series and review of the literature

Shrinking lung syndrome (SLS) is a rare and less known complication mainly associated with systemic lupus erythematosus (SLE). In this study, we analyze the clinical features, investigation findings, approaches to management, and outcome in a case series of 9 adult patients with SLE and SLS diagnosed during a 35-year period in 3 referral tertiary care hospitals in Spain. Additionally, we reviewed 80 additional cases previously reported (PubMed 1965-2015). These 80 cases, together with our 9 patients, form the basis of the present analysis.The overall SLS prevalence in our SLE population was 1.1% (9/829). SLS may complicate SLE at any time over its course, and it usually occurs in patients without previous or concomitant major organ involvement. More than half of the patients had inactive lupus according to SELENA-systemic lupus erythematosus disease activity index (SLEDAI) scores. Typically, it presents with progressive exertional dyspnea of variable severity, accompanied by pleuritic chest pain in 76% of the cases.An important diagnostic delay is common. The diagnostic tools that showed better yield for SLS detection are the imaging techniques (chest x-ray and high-resolution computed tomography) along with pulmonary and diaphragmatic function tests. Evaluation of diaphragm dome motion by M-mode ultrasonography and phrenic nerve conduction studies are less useful.There are no standardized guidelines for the treatment of SLS in SLE. The majority of patients were treated with medium or high doses of glucocorticoids. Several immunosuppressive agents have been used in conjunction with steroids either if the patient fails to improve or since the beginning of the treatment. Theophylline and beta-agonists, alone or in combination with glucocorticoids, have been suggested with the intent to increase diaphragmatic strength.The overall long-term prognosis was good. The great majority of patients had significant clinical improvement and stabilization, or mild to moderate improvement on pulmonary function tests. The mortality rate was very low.

Which dose of steroids and which cytotoxics for severe lupus?

There have been a number of major advances in the treatment of systemic lupus erythematosus and we are now in the era of biologic therapies for this multisystem autoimmune disorder. There has been a greater awareness of the toxicities of the traditional therapies including the recognition that the doses of corticosteroids used in the past have been excessive, resulting in unacceptable toxicities. Other advances have included the development of lower cumulative doses of cyclophosphamide and the widespread acceptance of mycophenolate mofetil for the treatment of lupus nephritis. This review addresses the current management of severe lupus with corticosteroids and cytotoxic agents.

Rituximab in the treatment of shrinking lung syndrome in systemic lupus erythematosus

Shrinking lung syndrome (SLS) is a rare manifestation of systemic lupus erythematosus. We report the case of a patient with non-responding SLS (neither to glucocorticoids nor immunosupresors), who showed remarkable improvement after the onset of treatment with rituximab. Although there is a little evidence, treatment with rituximab could be proposed in SLS when classical treatment fails.

Symptoms of shrinking lung syndrome reveal systemic lupus erythematosus in a 12-year-old girl

While pleuropulmonary involvement in systemic lupus erythematosus (SLE) is a common occurrence, shrinking lung syndrome (SLS) is a rare complication of SLE, particularly in children. We report on a teenager girl with a primary SLE diagnosis, which was based upon clinical, imaging, lung-function and histological findings ascertained to be compatible with SLS. Following a pneumonia, the patient developed inflammatory residues in the lower lobes, an event that probably caused diaphragmatic immobility and subsequently led to SLS. Treatment response to steroids, cyclophosphamide and hydroxychloroquine in this case was excellent, and efficacy was more profound than previously has been reported in the literature with respect to pediatric patients. This case report argues that prognosis of SLS in SLE is likely to be favorable when the diagnosis is made early and the disease is treated appropriately.

Shrinking lung syndrome masked by pleuropericarditis: a case report and review of the literature

The purpose of this article is to present an unusual case of shrinking lung syndrome (SLS) masked by pleuropericarditis with a review of the literature. We report a case of SLS in a 44-year-old woman in which the diagnosis was initially confounded by concurrent pleuropericarditis. The English medical literature was comprehensively reviewed for SLS for its presentation, clinical findings, diagnosis, treatment, with specific focus on its pathogenesis. SLS is a rare respiratory complication associated with systemic lupus erythematosus (SLE). The main manifestation of the disease is unexplained dyspnea, chest pain, and orthopnea. Lung volume reduction without parenchymal abnormalities along with restrictive ventilatory defect on pulmonary function test (PFT) is the hallmarks of this condition. Pathogenesis, treatment, and prognosis of SLS are not well described due to the small number of reported cases. The diagnosis of SLS in our patient was made based on imaging, PFT, and the exclusion of other respiratory diseases associated with SLE. Treatment with corticosteroid and intravenous cyclophosphamide was initiated due to simultaneously diagnosed renal involvement. Our case demonstrates the salient features of SLS. It emphasizes that although SLS is a rare disease limited to small subset of patients with SLE, it should be considered in patients with SLE with unexplained dyspnea. Moreover, symptoms of pleuropericarditis can mask and delay the diagnosis of SLS. Prompt diagnosis and treatment can lead to a decrease in morbidity and stabilization of pulmonary function test abnormalities.

Evaluating systemic lupus erythematosus patients for lung involvement

Introduction: We set out to determine the frequency of respiratory symptoms, abnormal lung function, and shrinking lung syndrome (SLS) among patients with systemic lupus erythematosus (SLE) and to determine correlates of SLS. Methods: Consecutive adult patients who fulfilled the American College of Rheumatology classification criteria for SLE were enrolled. Demographics, clinical, and serologic characteristics were recorded; all patients underwent pulmonary function tests (PFT) and had either a chest X-ray or computed tomography scan. SLS was defined as dyspnea with restrictive lung physiology (defined as a forced vital capacity (FVC) <80% predicted in the absence of obstruction) who did not have any evidence of interstitial lung disease on chest imaging; controls were symptomatic patients with no restrictive physiology and the absence of interstitial changes on chest imaging. Results: Sixty-nine out of 110 (63%) patients had respiratory symptoms, 73 (66%) patients had abnormal lung function, and 11 (10%) patients met the definition for SLS. In a multivariate model controlling for disease duration, a history of pleuritis, modified American College of Rheumatology total score, seropositivity for dsDNA and RNP antibodies, increased disease duration (odds ratio (OR) = 1.2; 95% confidence interval (CI) of 1.0–1.3, p = 0.04), seropositivity for anti-RNP (OR = 24.4; 95% CI of 1.6–384.0, p = 0.02), and a history of serositis were significantly associated with SLS when compared with symptomatic controls. Conclusion: Respiratory symptoms, abnormal lung function, and SLS are common in SLE. Clinicians should consider evaluation for SLS among symptomatic patients with long-standing disease and a history of pleuritis.

Current state of evidence on 'off-label' therapeutic options for systemic lupus erythematosus, including biological immunosuppressive agents, in Germany, Austria and Switzerland--a consensus report

Systemic lupus erythematosus (SLE) can be a severe and potentially life-threatening disease that often represents a therapeutic challenge because of its heterogeneous organ manifestations. Only glucocorticoids, chloroquine and hydroxychloroquine, azathioprine, cyclophosphamide and very recently belimumab have been approved for SLE therapy in Germany, Austria and Switzerland. Dependence on glucocorticoids and resistance to the approved therapeutic agents, as well as substantial toxicity, are frequent. Therefore, treatment considerations will include 'off-label' use of medication approved for other indications. In this consensus approach, an effort has been undertaken to delineate the limits of the current evidence on therapeutic options for SLE organ disease, and to agree on common practice. This has been based on the best available evidence obtained by a rigorous literature review and the authors' own experience with available drugs derived under very similar health care conditions. Preparation of this consensus document included an initial meeting to agree upon the core agenda, a systematic literature review with subsequent formulation of a consensus and determination of the evidence level followed by collecting the level of agreement from the panel members. In addition to overarching principles, the panel have focused on the treatment of major SLE organ manifestations (lupus nephritis, arthritis, lung disease, neuropsychiatric and haematological manifestations, antiphospholipid syndrome and serositis). This consensus report is intended to support clinicians involved in the care of patients with difficult courses of SLE not responding to standard therapies by providing up-to-date information on the best available evidence.

Colitis associated with active systemic lupus erythematosus successfully treated with rituximab

Intestinal vasculitis is a serious and often underrecognized complication of systemic lupus erythematosus (SLE) usually managed with high-dose corticosteroids. We report a case of corticosteroid refractory colitis (likely due to intestinal vasculitis) that achieved remission with a single cycle of high-dose rituximab. This has not previously been described to our knowledge. A 46-year-old woman with SLE presented with 1-week history of bloody diarrhea, abdominal pain, worsening joint pains, fatigue, and mouth ulcers. There was evidence of increased SLE activity with low C4, raised anti-double-stranded DNA antibody, leukopenia, and anemia. Colonoscopy showed active pancolitis (confirmed histologically). A diagnosis of acute colitis associated with active SLE was made, and she received intravenous methylprednisolone 1 g daily for 3 days followed by 60 mg oral prednisolone daily. She continued to have symptomatic colitis with worsening anemia requiring frequent blood transfusions. She then received 2 doses of rituximab 1 g (750 mg/m(2)) 2 weeks apart that led to improvement in colitis symptoms and SLE disease activity over the next 4 weeks. A repeat colonoscopy (and histology) confirmed good resolution of colitis. Six months later, she continued to be in remission with low-dose prednisolone. Intestinal vasculitis should be considered as a possible cause of acute abdominal pain in SLE as early recognition and treatment can improve long-term survival. Rituximab can be an effective alternative for patients refractory to conventional treatment.

Shrinking lung syndrome: recognition, pathophysiology and therapeutic strategy

Shrinking lung syndrome is a rare complication of systemic autoimmune diseases, mainly systemic lupus erythematosus, but also Sjögren's syndrome and polymyositis. It should be suspected in any patient with autoimmune disease presenting with an unexplained dyspnea. Shrinking lung syndrome is characterized by small lung volumes, elevation of the diaphragm and restrictive physiology without parenchymal involvement. Its pathogenesis remains controversial: diaphragm dysfunction, phrenic neuropathy or pleural inflammation. Pleural adhesions and pain probably play a significant role in the pathogenesis. Electrical or magnetic phrenic stimulation is an important method of investigation but it is not widely available. No treatment has been validated. Steroids are proposed as first-line treatment, alone or associated with β2-adrenergic receptor agonists. In refractory cases, immunosuppressors are used. Biotherapies may be beneficial. Long-term prognosis is good, but respiratory failure can occur in some cases.