Connective tissue disease-associated interstitial lung disease (CTD-ILD) represents a group of systemic autoimmune disorders characterized by immune-mediated organ dysfunction. Systemic sclerosis, rheumatoid arthritis, idiopathic inflammatory myositis, and Sjögren's syndrome are the most common CTDs that present with pulmonary involvement, as well as with interstitial pneumonia with autoimmune features. The frequency of CTD-ILD varies according to the type of CTD, but the overall incidence is 15%, causing an important impact on morbidity and mortality. The decision of which CTD patient should be investigated for ILD is unclear for many CTDs. Besides that, the clinical spectrum can range from asymptomatic findings on imaging to respiratory failure and death. A significant proportion of patients will present with a more severe and progressive disease, and, for those, immunosuppression with corticosteroids and cytotoxic medications are the mainstay of pharmacological treatment. In this review, we summarized the approach to diagnosis and treatment of CTD-ILD, highlighting recent advances in therapeutics for the various forms of CTD.

Keywords: Lung diseases, interstitial; Collagen diseases; Scleroderma, systemic; Arthritis, rheumatoid; Myositis; Therapeutics.

The initial evaluation of patients with interstitial lung disease (ILD) primarily involves a comprehensive, active search for the cause. Autoantibody assays, which can suggest the presence of a rheumatic disease, are routinely performed at various referral centers. When interstitial lung involvement is the condition that allows the definitive diagnosis of connective tissue disease and the classical criteria are met, there is little debate. However, there is still debate regarding the significance, relevance, specificity, and pathophysiological role of autoimmunity in patients with predominant pulmonary involvement and only mild or benign symptoms of connective tissue disease. The purpose of this article was to review the current knowledge of autoantibody positivity and to discuss its possible interpretations in patients with ILD and without clear etiologic associations, as well as to enhance the understanding of the natural history of an allegedly new disease and to describe the possible prognostic implications. We also discuss the proposition of a new term to be used in the classification of ILDs: lung-dominant connective tissue disease.

Keywords: Idiopathic interstitial pneumonias; Autoantibodies; Connective tissue diseases; Autoimmune diseases; Diagnosis, differential.

Objective: To describe the characteristics of a cohort of patients with lung-dominant connective tissue disease (LD-CTD). Methods: This was a retrospective study of patients with interstitial lung disease (ILD), positive antinuclear antibody (ANA) results (≥ 1/320), with or without specific autoantibodies, and at least one clinical feature suggestive of connective tissue disease (CTD). Results: Of the 1,998 patients screened, 52 initially met the criteria for a diagnosis of LD-CTD: 37% were male; the mean age at diagnosis was 56 years; and the median follow-up period was 48 months. During follow-up, 8 patients met the criteria for a definitive diagnosis of a CTD. The remaining 44 patients comprised the LD-CTD group, in which the most prevalent extrathoracic features were arthralgia, gastroesophageal reflux disease, and Raynaud's phenomenon. The most prevalent autoantibodies in this group were ANA (89%) and anti-SSA (anti-Ro, 27%). The mean baseline and final FVC was 69.5% and 74.0% of the predicted values, respectively (p > 0.05). Nonspecific interstitial pneumonia and usual interstitial pneumonia patterns were found in 45% and 9% of HRCT scans, respectively; 36% of the scans were unclassifiable. A similar prevalence was noted in histological samples. Diffuse esophageal dilatation was identified in 52% of HRCT scans. Nailfold capillaroscopy was performed in 22 patients; 17 showed a scleroderma pattern. Conclusions: In our LD-CTD group, there was predominance of females and the patients showed mild spirometric abnormalities at diagnosis, with differing underlying ILD patterns that were mostly unclassifiable on HRCT and by histology. We found functional stability on follow-up. Esophageal dilatation on HRCT and scleroderma pattern on nailfold capillaroscopy were frequent findings and might come to serve as diagnostic criteria.

Keywords: Idiopathic interstitial pneumonias; Autoantibodies; Connective tissue diseases; Autoimmunity.

The use of immunobiological agents for the treatment of autoimmune diseases is increasing in medical practice. Anti-TNF therapies have been increasingly used in refractory autoimmune diseases, especially rheumatoid arthritis, with promising results. However, the use of such therapies has been associated with an increased risk of developing other autoimmune diseases. In addition, the use of anti-TNF agents can cause pulmonary complications, such as reactivation of mycobacterial and fungal infections, as well as sarcoidosis and other interstitial lung diseases (ILDs). There is evidence of an association between ILD and the use of anti-TNF agents, etanercept and infliximab in particular. Adalimumab is the newest drug in this class, and some authors have suggested that its use might induce or exacerbate preexisting ILDs. In this study, we report the first case of acute ILD secondary to the use of adalimumab in Brazil, in a patient with rheumatoid arthritis and without a history of ILD.

Keywords: Lung diseases, interstitial; Arthritis, rheumatoid; Antirheumatic agents; Antibodies, monoclonal, humanized/adverse effects.

Objective: To correlate the prevalence and prognosis of each HRCT pattern of typical, probable, and indeterminate usual interstitial pneumonia (UIP) with the clinical multidisciplinary diagnosis of interstitial lung disease (ILD). Methods: We included all patients with a multidisciplinary diagnosis of ILD with an HRCT pattern of typical UIP, probable UIP, or indeterminate for UIP. Clinical and histopathological data, pulmonary function tests, and survival status were retrospectively obtained. The final diagnosis was validated by a multidisciplinary team. Results: A total of 244 patients were included in the study, with a mean age of 68 ±13 years and being 52.5% males. In a total of 106 patients with typical UIP pattern, 62% had the multidisciplinary diagnosis of IPF, 20% had chronic hypersensitivity pneumonitis (CHP), and 10% had connective tissue disease-related ILD (CTD-ILD). Out of the 114 cases with probable UIP, CTD-ILD corresponded to 39%, IPF to 31%, desquamative interstitial pneumonia to 11%, drug-related lung disease to 9%, and CHP to 8%. In the 24 patients with CT indeterminate for UIP, CTD-ILD was the final diagnosis in 33%, followed by desquamative interstitial pneumonia (21%), and IPF (13%). Patients with typical UIP were more likely to die or had lung transplantation in the follow-up (17.9% and 11.3%, respectively). Conclusion: IPF, CHP, and CTD-ILD were the main differential diagnoses in patients with HRCT patterns of typical, probable and indeterminate UIP. Patients with HRCT typical UIP pattern were more likely to die or had lung transplantation in the follow-up.

Keywords: High resolution computed tomography; Interstitial lung disease; Idiopathic pulmonary fibrosis; Usual interstitial pneumonia.

Respiratory bronchiolitis-associated interstitial lung disease is one of many within the spectrum of smoking-related diffuse infiltrative lung diseases. The clinical and functional characteristics are typically subtle. Herein, we describe two cases of diagnosed through open-lung biopsy, and characterized by insidious evolution of dyspnea, digital clubbing, cystic lesions on computed tomography scans, and hipoxemia upon exertion. We emphasize that, when smokers are evaluated, it is imprtant to consider a diagnosis of respiratory bronchiolitis-associated interstitial lung disease in the context of interstitial cystitis, as well as in that of lymphangioleiomyomatosis, eosinophilic granuloma and idiophatic pulmonary fibrosis.

Keywords: Smoking. Interstitial lung diseases. Bronchiolitis.

Many interstitial lung diseases (ILDs) share mechanisms that result in a progressive fibrosing phenotype. In Brazil, the most common progressive fibrosing interstitial lung diseases (PF-ILDs) are chronic hypersensitivity pneumonitis, idiopathic pulmonary fibrosis, unclassified ILD, and connective tissue diseases. PF-ILD is seen in approximately 30% of patients with ILD. Because PF-ILD is characterized by disease progression after initiation of appropriate treatment, a diagnosis of the disease resulting in fibrosis is critical. Different criteria have been proposed to define progressive disease, including worsening respiratory symptoms, lung function decline, and radiological evidence of disease progression. Although the time elapsed between diagnosis and progression varies, progression can occur at any time after diagnosis. Several factors indicate an increased risk of progression and death. In the last few years, antifibrotic drugs used in patients with idiopathic pulmonary fibrosis have been tested in patients with PF-ILD. The effects of nintedanib and placebo have been compared in patients with PF-ILD, a mean difference of 107.0 mL/year being observed, favoring nintedanib. The U.S. Food and Drug Administration and the Brazilian Health Regulatory Agency have approved the use of nintedanib in such patients on the basis of this finding. Pirfenidone has been evaluated in patients with unclassified ILD and in patients with other ILDs, the results being similar to those for nintedanib. More studies are needed in order to identify markers of increased risk of progression in patients with ILD and determine the likelihood of response to treatment with standard or new drugs.

Keywords: Alveolitis, extrinsic allergic; Idiopathic pulmonary fibrosis; Lung diseases, interstitial; Connective tissue diseases.

Objective: To investigate the correlation of HRCT findings with pulmonary metabolic activity in the corresponding regions using 18F-FDG PET/CT and inflammatory markers in patients with systemic sclerosis (SSc)-associated interstitial lung disease (ILD). Methods: This was a cross-sectional study involving 23 adult patients with SSc-associated ILD without other connective tissue diseases. The study also involved 18F-FDG PET/CT, HRCT, determination of serum chemokine levels, clinical data, and pulmonary function testing. Results: In this cohort of patients with long-term disease (disease duration, 11.8 ± 8.7 years), a nonspecific interstitial pneumonia pattern was found in 19 (82.6%). Honeycombing areas had higher median standardized uptake values (1.95; p = 0.85). Serum levels of soluble tumor necrosis factor receptor 1, soluble tumor necrosis factor receptor 2, C-C motif chemokine ligand 2 (CCL2), and C-X-C motif chemokine ligand 10 were higher in SSc patients than in controls. Serum levels of CCL2-a marker of fibroblast activity-were correlated with pure ground-glass opacity (GGO) areas on HRCT scans (p = 0.007). 18F-FDG PET/CT showed significant metabolic activity for all HRCT patterns. The correlation between serum CCL2 levels and GGO on HRCT scans suggests a central role of fibroblasts in these areas, adding new information towards the understanding of the mechanisms surrounding cellular and molecular elements and their expression on HRCT scans in patients with SSc-associated ILD. Conclusions: 18F-FDG PET/CT appears to be unable to differentiate the intensity of metabolic activity across HRCT patterns in chronic SSc patients. The association between CCL2 and GGO might be related to fibroblast activity in these areas; however, upregulated CCL2 expression in the lung tissue of SSc patients should be investigated in order to gain a better understanding of this association.

Keywords: Tomography; Lung diseases, interstitial; Scleroderma, systemic; Cytokines.

In patients with myositis, the lung is commonly involved, and the presence of anti-aminoacyl-tRNA synthetase (anti-ARS) antibodies marks the presence or predicts the development of interstitial lung disease (ILD). A distinct clinical entity-antisynthetase syndrome-is characterized by the presence of anti-ARS antibodies, myositis, ILD, fever, arthritis, Raynaud's phenomenon, and mechanic's hands. The most common anti-ARS antibody is anti-Jo-1. More recently described anti-ARS antibodies might confer a phenotype that is distinct from that of anti-Jo-1-positive patients and is characterized by a lower incidence of myositis and a higher incidence of ILD. Among patients with antisynthetase syndrome-related ILD, the response to immunosuppressive medications is generally, but not universally, favorable.

Keywords: Lung diseases, interstitial; Pneumonia; Infection.

Objective: To study the clinical, radiological, and histopathological patterns of transbronchial biopsy (TBB) used in order to confirm the diagnosis in patients with clinical suspicion of interstitial lung disease (ILD) treated at a tertiary-care university hospital. Methods: We reviewed the medical records, radiology reports, and reports of transbronchial biopsies from all patients with suspected ILD who underwent TBB between January of 1999 and December of 2006 at the Hospital das Clínicas de Botucatu, located in the city of Botucatu, Brazil. Results: The study included 56 patients. Of those, 11 (19.6%) had a definitive diagnosis of idiopathic pulmonary fibrosis (IPF), the rate of which was significantly higher in the patients in which ILD was a possible diagnosis in comparison with those in which ILD was the prime suspect (p = 0.011), demonstrating the contribution of TBB to the diagnostic confirmation of these diseases. The histopathological examination of the biopsies revealed that 27.3% of the patients with IPF showed a pattern of organizing pneumonia, which suggests greater disease severity. The most common histological pattern was the indeterminate pattern, reflecting the peripheral characteristic of IPF. However, the fibrosis pattern showed high specificity and high negative predictive value. For CT scan patterns suggestive of IPF, the ROC curve showed that the best relationship between sensitivity and specificity occurred when five radiological alterations were present. Honeycombing was found to be strongly suggestive of IPF (p = 0.01). Conclusions: For ILDs, chest CT should always be performed, and TBB should be used in specific situations, according to the suspicion and distribution of lesions.

Keywords: Lung diseases, interstitial; Diagnosis, differential; Bronchoscopy.

A 35 year-old black woman, previously healthy, who complained about chronic cough and shortness of breath was investigated after non-response of symptoms. Her chest X-ray and high resolution chest CT-scan were normal. She presented with abnormal spirometry, a mild restrictive disturbance. After a negative initial clinical investigation, an open lung biopsy was indicated. Multiple microscopic peribronchiolar tumorlets carcinoids - neuroendocrine cell hyperplasia was revealed. The authors emphasize the importance of an early diagnosis of this unusual entity and discuss its possible pathophysiological mechanisms.

Keywords: Lung diseases. Neuroendocrine cell. Bronchiolitis. Carcinoid. Tumorlets.