Cryptogenic fibrosing alveolitis and the fibrosing alveolitis of systemic sclerosis: morphological differences on computed tomographic scans

Heterogeneity of determining disease severity, clinical course and outcomes in systemic sclerosis-associated interstitial lung disease: a systematic literature review

Objective The course of systemic sclerosis-associated interstitial lung disease (SSc-ILD) is highly variable and different from continuously progressive idiopathic pulmonary fibrosis (IPF). Most proposed definitions of progressive pulmonary fibrosis or SSc-ILD severity are based on the research data from patients with IPF and are not validated for patients with SSc-ILD. Our study aimed to gather the current evidence for severity, progression and outcomes of SSc-ILD.Methods A systematic literature review to search for definitions of severity, progression and outcomes recorded for SSc-ILD was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in Medline, Embase, Web of Science and Cochrane Library up to 1 August 2023.Results A total of 9054 papers were reviewed and 342 were finally included. The most frequent tools used for the definition of SSc-ILD progression and severity were combined changes of carbon monoxide diffusing capacity (DLCO) and forced vital capacity (FVC), isolated FVC or DLCO changes, high-resolution CT (HRCT) extension and composite algorithms including pulmonary function test, clinical signs and HRCT data. Mortality was the most frequently reported long-term event, both from all causes or ILD related.Conclusions The studies presenting definitions of SSc-ILD 'progression', 'severity' and 'outcome' show a large heterogeneity. These results emphasise the need for developing a standardised, consensus definition of severe SSc-ILD, to link a disease specific definition of progression as a surrogate outcome for clinical trials and clinical practice.PROSPERO registration number CRD42022379254.Cite Now.

Responses to exercise in systemic sclerosis-associated interstitial lung disease

INTRODUCTION

Pulmonary complications in systemic sclerosis (SSc) significantly increase morbidity and mortality. Our aim was to determine the factors limiting exercise capacity in SSc patients with and without interstitial lung disease (ILD), and to identify and quantify abnormalities during exercise that might assist in clinical assessment of this complication.

METHODS

Fifteen patients with SSc and ILD (SSc-ILD) were compared with 10 patients with SSc without ILD and 9 age- and sex-matched normal volunteers. Subjects performed symptom-limited incremental treadmill exercise with online measurement of respiratory gas exchange, arterial blood gas sampling and measurement of neurohormones in venous blood.

RESULTS

Patients with SSc-ILD had lower exercise capacity than SSc patients without ILD or normal subjects (peak oxygen consumption (PV̇O₂ ) (17.1 [4.2] vs. 22.0 [4.7] and 23.0 [5.4] ml kg^-1  min^-1 , respectively, mean [SD], p < 0.01 ANOVA), but PV̇O₂ did not correlate with static pulmonary function measurements. Ventilatory equivalent for CO₂ (V̇E/V̇CO₂ ; nadir) was higher in SSc-ILD patients than the other two groups (36.6 [8.0] vs. 29.9 [4.4] and 30.0 [2.5], p < 0.005) as were peak exercise dead-space tidal volume ratio (0.44 [0.06] vs. 0.26 [0.09] and 0.26 [0.05], p < 0.001) and peak exercise alveolar-arterial difference (28.9 [16.9] vs. 18.8 [14.0] and 11.5 [6.9] mmHg, p < 0.05). Atrial natriuretic peptide was elevated in both SSc patient groups.

CONCLUSIONS

SSc-ILD results in lower exercise capacity than SSc without ILD, and abnormalities of gas exchange are seen. The possible use of cardiopulmonary exercise testing to identify disease and quantify impairment in SSc-ILD merits further study.

Study of the Correlation between HRCT Semi-quantitative Scoring, Concentration of Alveolar Nitric Oxide, and Clinical-functional Parameters of Systemic Sclerosis-induced Interstitial Lung Disease

Introduction: The correlation between alveolar nitric oxide (CANO) and the severity of interstitial lung disease (ILD) evaluated by high resolution computed tomography (HRCT) has not been well demonstrated. Methods: It was a perspective and observational study, including patients with diagnosed systemic sclerosis (SSc). They performed lung function testing (LFT), exhaled nitric oxide (NO) measurements, exercise testing, chest X-ray, and HRCT. Study patients were divided into SSc with ILD (SSc-ILD+) or without ILD (SSc-ILD-). SSC-ILD+ patients were revisited after 6 months and 12 months to complete the study. Results: Thirty-one control subjects and 74 patients with SSc (33 SSc-ILD- and 41 SSc-ILD+) were included. Forty-one SSc-ILD+ patients were followed-up at 6 months and 12 months. Lung functional parameters of patients with SSc-ILD+ were lower than that of SSc-ILD- patients. The level of CANO was significantly higher in SSc-ILD+ than SSc-ILD- patients (8.6 ± 2.5 vs 4.2 ± 1.3 ppb and P<0.01). Warrick and Goldin scores of patients with SSc-ILD+ were respectively 16.5 ± 5.2 and 12.7 ± 4.3. Warrick scores were reduced after 6 and 12 months of follow-up vs at inclusion (12.4 ± 4.3 and 9.1 ± 3.2 vs 16.5 ± 5.2; P<0.05, P<0.01, and P<0.05; respectively). ΔWarrick and ΔGoldin scores were significantly and inversely correlated with ΔFVC, ΔTLC, ΔTLCO, ΔVO₂ max; that was also correlated with ΔCANO (R= 0.783, P<0.01 and R= 0.719 and P<0.05). Conclusion: CANO is a relevant biomarker for the diagnosis of ILD in patients with SSc, especially in combination with HRCT.

Genetic predictors of systemic sclerosis-associated interstitial lung disease: a review of recent literature

The interplay between genetic and environmental factors is likely involved in the pathogenesis of systemic sclerosis (SSc). Interstitial lung disease associated in the context of SSc (SSc-ILD) is associated with significant morbidity, and is the leading cause of death in SSc. The spectrum of SSc-ILD severity is wide, ranging from patients with only limited and inherently stable pulmonary involvement, to those with extensive and progressive pulmonary fibrosis. In order to provide accurate prognostic information for patients, and to initiate appropriate monitoring and treatment regimens, the ability to identify patients at risk of developing severe ILD early in the disease course is crucial. Identification of genetic variants involved in disease pathogenesis can not only potentially provide diagnostic/prognostic markers, but can also highlight dysregulated molecular pathways for therapeutic targeting. A number of genetic associations have been established for susceptibility to SSc, but far fewer studies have investigated genetic susceptibility to SSc-ILD specifically. In this review we present a summary of the studies assessing genetic associations with SSc-ILD.

Imaging of pulmonary involvement in rheumatic disease

Lung disease commonly occurs in connective tissue diseases (CTD) and is an important cause of morbidity and mortality. Imaging is central to the evaluation of CTD-associated pulmonary complications. In this article, a general discussion of radiologic considerations is followed by a description of the pulmonary appearances in individual CTDs, and the imaging appearances of acute and nonacute pulmonary complications. The contribution of imaging to monitoring disease, evaluating treatment response, and prognostication is reviewed. Finally, we address the role of imaging in the challenging multidisciplinary evaluation of interstitial lung disease where there is an underlying suspicion of an undiagnosed CTD.

Pneumonia intersticial associada à esclerose sistêmica: avaliação da função pulmonar no período de cinco anos

OBJETIVO: Avaliar as alterações da função pulmonar em portadores de pneumonia intersticial associada à esclerose sistêmica no intervalo de cinco anos. MÉTODOS: Foi realizado um estudo longitudinal no qual foram avaliados 35 pacientes não tabagistas com esclerose sistêmica e sem história de doença pulmonar prévia. Na primeira avaliação, realizada na época do diagnóstico da pneumonia intersticial, os pacientes foram submetidos à TCAR, espirometria e medida de DLCO. Os pacientes foram subdivididos em dois grupos de acordo com a presença ou não de faveolamento na TCAR. Aproximadamente cinco anos após a primeira avaliação, os pacientes foram submetidos a espirometria e medida da DLCO apenas. RESULTADOS: Dos 35 pacientes, 34 eram mulheres, com média de idade de 47,6 anos. A média de tempo entre as duas avaliações foi de 60,9 meses. O faveolamento foi demonstrado por TCAR em 17 pacientes. Na amostra total, após cinco anos do diagnóstico, CVF, VEF1 e DLCO reduziram significativamente (81,3 ± 18,2% vs. 72,1 ± 22,2%; 79,9 ± 17,8% vs. 72,5 ± 20,6%; e 74,0 ± 20,5% vs. 60,7 ± 26,8%, respectivamente; p = 0.0001 para todos), enquanto a relação VEF1/CVF aumentou significativamente (98,5 ± 7,2% vs. 101,9 ± 7,8%; p = 0,008). No mesmo período, os valores de CVF, VEF1 e DLCO foram significativamente menores nos pacientes com faveolamento do que naqueles sem faveolamento na TCAR (p = 0,0001). CONCLUSÕES: Na esclerose sistêmica com doença pulmonar intersticial associada, a detecção de faveolamento na TCAR é determinante para predizer uma deterioração acelerada da função pulmonar.

Severity classification for idiopathic pulmonary fibrosis by using fuzzy logic

OBJECTIVE

To set out a severity classification for idiopathic pulmonary fibrosis (IPF) based on the interaction of pulmonary function parameters with high resolution computed tomography (CT) findings.

INTRODUCTION

Despite the contribution of functional and radiological methods in the study of IPF, there are few classification proposals for the disease based on these examinations.

METHODS

A cross-sectional study was carried out, in which 41 non-smoking patients with IPF were evaluated. The following high resolution CT findings were quantified using a semi-quantitative scoring system: reticular abnormality, honeycombing and ground-glass opacity. The functional variables were measured by spirometry, forced oscillation technique, helium dilution method, as well as the single-breath method of diffusing capacity of carbon monoxide. With the interaction between functional indexes and high resolution CT scores through fuzzy logic, a classification for IPF has been built.

RESULTS

Out of 41 patients studied, 26 were male and 15 female, with a mean age of 70.8 years. Volume measurements were the variables which showed the best interaction with the disease extension on high resolution CT, while the forced vital capacity showed the lowest estimative errors in comparison to total lung capacity. A classification for IPF was suggested based on the 95% confidence interval of the forced vital capacity %: mild group (>92.7); moderately mild (76.9-92.6); moderate (64.3-76.8%); moderately severe (47.1-64.2); severe (24.3-47.0); and very severe (<24.3).

CONCLUSION

Through fuzzy logic, an IPF classification was built based on forced vital capacity measurement with a simple practical application.

Computed tomographic features of idiopathic fibrosing interstitial pneumonia: comparison with pulmonary fibrosis related to collagen vascular disease

OBJECTIVE

To compare the computed tomographic (CT) features of idiopathic fibrosing interstitial pneumonia with those of pulmonary fibrosis related to collagen vascular disease (CVD).

METHODS

We reviewed the CT scans of 177 patients with diffuse interstitial pulmonary fibrosis, of which 97 had idiopathic fibrosing interstitial pneumonia and 80 had CVD. The CT images were systematically scored for the presence and extent of pulmonary and extrapulmonary abnormalities. Computed tomographic diagnosis of usual interstitial pneumonia (UIP) or nonspecific interstitial pneumonia (NSIP) was assigned.

RESULTS

A CT pattern of UIP was identified in 59 (60.8%) of patients with idiopathic fibrosing interstitial pneumonia compared with 15 (18.7%) of those patients with CVD; conversely, the CT diagnosis of NSIP was made in 51 (64%) of patients with CVD compared with 36 (37%) of patients with idiopathic disease (P < 0.01). In 113 patients who had lung biopsy, the CT diagnoses of UIP and NSIP were concordant with the histologic diagnoses in 36 of 50 patients and 34 of 41 patients, respectively. Pleural effusions, esophageal dilation, and pericardial abnormalities were more frequent in patients with CVD than in patients with idiopathic fibrosing interstitial pneumonia.

CONCLUSIONS

Compared with patients with CVD, those patients with an idiopathic fibrosing interstitial pneumonia showed a higher prevalence of a UIP pattern and lower prevalence of an NSIP pattern as determined by CT. Identification of coexisting extrapulmonary abnormalities on CT can support a diagnosis of CVD.

Correlação dos achados tomográficos com parâmetros de função pulmonar na fibrose pulmonar idiopática em não fumantes

OBJETIVO: Correlacionar os achados tomográficos com os parâmetros de função pulmonar em portadores de fibrose pulmonar idiopática (FPI). MÉTODOS: Foi realizado um estudo de corte transversal, em que foram avaliados 30 pacientes não tabagistas, portadores de FPI. Utilizando um sistema de escore semiquantitativo, os seguintes achados na tomografia computadorizada de alta resolução (TCAR) foram quantificados: extensão total da doença intersticial (Tot), infiltrado reticular e faveolamento (Ret+Fav), e opacidade em vidro fosco (Vif). As variáveis funcionais foram mensuradas através de espirometria, técnica de oscilações forçadas (TOF), método da diluição com hélio e método da respiração única para medir a capacidade de difusão do monóxido de carbono (DLCO). RESULTADOS: Dos 30 pacientes estudados, 18 eram mulheres e 12 eram homens, com média de idade de 70,9 anos. Foram encontradas correlações significativas de Tot e Ret+Fav com as medidas de capacidade vital forçada (CVF), capacidade pulmonar total (CPT), DLCO e complacência dinâmica do sistema respiratório (correlações negativas), e de Vif com volume residual/CPT (correlação positiva). A relação fluxo expiratório forçado entre 25 e 75% da CVF/CVF (FEF25-75%/CVF) correlacionou-se positivamente com Tot, Ret+Fav e Vif. CONCLUSÕES: Em portadores de FPI, as medidas de volume, difusão e complacência dinâmica são as variáveis fisiológicas que melhor refletem a extensão da doença intersticial na TCAR.

Lung CT densitometry in systemic sclerosis: correlation with lung function, exercise testing, and quality of life

BACKGROUND

To ascertain if analysis of lung density histograms in thin-section CT was more reproducible than visual assessment of lung changes in systemic sclerosis (SSc), and if such density histogram parameters as mean lung attenuation (MLA), skewness, and kurtosis could more closely reflect pulmonary function as well as exercise and quality of life impairment.

METHODS

The intraoperator and interoperator reproducibility of visual and densitometric lung CT analysis in 48 SSc patients examined with CT were evaluated by means of weighted kappa statistics. Univariate and multivariate regression analyses were applied to evaluate the relationship of visual and densitometric CT measurements with functional parameters including functional residual capacity (FRC), FVC, FEV(1), diffusion capacity of the lung for carbon monoxide (Dlco), 6-min walking testing (6MWT), and health-related quality of life questionnaire (QLQ) parameters.

RESULTS

The intraoperator and interoperator reproducibility of MLA (intraobserver weighted kappa = 0.97; interobserver weighted kappa = 0.96), skewness (intraobserver weighted kappa = 0.89; interobserver weighted kappa = 0.88), and kurtosis (intraobserver weighted kappa = 0.89; interobserver weighted kappa = 0.88) were higher than those of visual assessment (intraobserver weighted kappa = 0.71; interobserver weighted kappa = 0.69). In univariate analysis, only densitometric measurements were correlated with some exercise and QLQ parameters. In multivariate analysis, MLA (square regression coefficient corrected [R(2)c] = 0.70), skewness (R(2)c = 0.78), and kurtosis (R(2)c = 0.77) were predicted by FRC, FVC, Dlco, 6MWT, and QLQ parameters, while visual assessment was associated only with FRC and FVC (R(2)c = 0.40).

CONCLUSIONS

In SSc, densitometric analysis is more reproducible than visual assessment of lung changes in thin-section CT and more closely correlated to pulmonary function testing, 6MWT, and QLQ. Density histogram parameters may be useful for cross-sectional and longitudinal studies of lung involvement in SSc.

Thin-Section and Low-Dose Volumetric Computed Tomographic Densitometry of the Lung in Systemic Sclerosis

OBJECTIVE

To correlate lung density measurements with the results of visual assessment of thin-section computed tomography (CT) and of pulmonary function tests (PFT) in Systemic Sclerosis (SSc).

METHODS

Thirty-nine SSc patients underwent sequential thin-section CT and spiral low-dose whole-lung acquisitions. The thin-section CT scans were evaluated with a dedicated visual scale. Mean lung density, skewness, and kurtosis were calculated from the lung density histogram. In addition from the spiral low-dose acquisition, the lung volume was computed. The visual score, the densitometric parameters, and the lung volume were correlated with the PFT.

RESULTS

Mean lung density, skewness, and kurtosis computed from thin-section (R = 0,66; R = -0,74; R = -0,75) and low-dose volumetric (R = 0,72; R = -0,71; R = -0,71) CT and the lung volume (R = -0.54) correlated with the visual score. Densitometric values and lung volume consistently better correlated with PFT than the visual score.

CONCLUSIONS

In SSc the histogram results are more closely correlated to PFT than the visual score. The low-dose spiral CT seems ideal for longitudinal studies.

Esclerose sistêmica progressiva: aspectos na tomografia computadorizada de alta resolução

OBJETIVO: Descrever os achados de tomografia computadorizada de alta resolução de pacientes com esclerose sistêmica pulmonar, independentemente dos sintomas respiratórios. MATERIAIS E MÉTODOS: Foram revisados 73 exames de tomografia computadorizada de alta resolução de 44 pacientes com diagnóstico de esclerodermia estabelecido através de critérios clínicos e laboratoriais. Os exames foram revisados por dois radiologistas, que estabeleceram os achados por consenso. RESULTADOS: Em 91,8% (n = 67) dos exames observaram-se alterações. Os principais achados foram lesões de padrão reticular (90,4%), opacidades em vidro-fosco (63%), bronquiectasias e bronquiolectasias de tração (56,2%), dilatação esofagiana (46,6%), faveolamento (28,8%) e sinais de hipertensão pulmonar (15,6%). Na maioria dos casos as lesões eram bilaterais (89%) e simétricas (58,5%). Quanto à localização, houve predomínio de lesões basais (91,2%) e periféricas (92,2%). CONCLUSÃO: A esclerose sistêmica progressiva acarreta fibrose pulmonar na maioria dos pacientes, caracterizada principalmente por lesão reticular basal e periférica.

« Classification 2002 des pneumopathies interstitielles idiopathiques »

OBJECTIVES

Diagnosis of interstitial lung diseases was recently improved by the use of diagnostic tools, such as high-resolution Computed Tomography, and by new insights in their pathogenesis and histology. This led the American Thoracic Society and the European Respiratory Society to propose a new classification of these diseases, in the aim to facilitate early diagnosis and specific care.

CURRENT KNOWLEDGE AND KEY POINTS

Standard radiography gives the first suspicion of chronic diffuse infiltrative lung disease, and anamnesis and physical examination are essential steps of etiological diagnosis. High-Resolution computed tomography confirms the diagnosis of diffuse infiltrative lung disease. Longitudinal lung function tests are essential to assess the consequences of the lung disease. Lung biopsies are often, but not systematically, a useful tool. The 2000 classification consists of seven entities of idiopathic interstitial diseases which are defined on clinical, radiological and pathological criteria: idiopathic pulmonary fibrosis, non-specific interstitial pneumonia, cryptogenic organizing pneumonia, acute interstitial pneumonia, respiratory bronchiolitis associated interstitial lung disease, desquamative interstitial pneumonia and lymphoid interstitial pneumonia. The most frequent is Idiopathic Pulmonary Fibrosis, which has a poor prognosis.

FUTURE PROSPECT AND PROJECTS

This new classification results from a multidisciplinary confrontation with chest physicians, radiologists and pathologists. A better characterization of anatomoclinical entities should lead to a better pronostic evaluation, more informative comparisons of published studies, and therefore to rational therapeutic approach.

Fibrosing alveolitis in systemic sclerosis: the need for early screening and treatment

Abnormalities in lung function occur in 70% of patients with systemic sclerosis (SSc). Fibrosing alveolitis in SSc (FASSc) is more commonly seen in the diffuse cutaneous form of SSc, particularly in the presence of antitopoisomerase antibodies (Scl70), and with the decreasing incidence of scleroderma renal crisis it is now the major cause of mortality in this patient population. Screening of patients recently diagnosed with SSc by pulmonary function tests and the performance of high resolution computed tomography when physiological abnormalities are identified has resulted in the identification of significant numbers of patients with early, asymptomatic FASSc. Whether these patients should be further investigated with a surgical lung biopsy or receive immunosuppression is unclear, because it cannot yet be reliably predicted who will develop progressive disease and the evidence to support the efficacy of treatment is not strong. The objective of the present article was to review the evidence to support the use of immunosuppressive therapy in FASSc and, based on these data, to propose an algorithm for the investigation and management of this difficult clinical problem.

CT features of lung disease in patients with systemic sclerosis: comparison with idiopathic pulmonary fibrosis and nonspecific interstitial pneumonia

PURPOSE

To evaluate computed tomographic (CT) patterns of lung disease in patients with systemic sclerosis (SSc) and compare them with CT appearance in patients with biopsy-proved idiopathic pulmonary fibrosis (IPF) and idiopathic nonspecific interstitial pneumonia (NSIP).

MATERIALS AND METHODS

The CT features of consecutive patients with SSc (n = 225; male patients, 44; female patients, 181; median age, 47 years; age range, 16-78 years), IPF (n = 40; men, 26; women, 14; median age, 54.5 years; age range, 36-77 years) and NSIP (n = 27; men, 18; women, nine; median age, 53 years; age range, 32-68 years) were quantified separately by two observers. The extent of interstitial lung disease, ground-glass opacification, emphysema, and the coarseness of a reticular pattern were quantified. Group comparisons were made nonparametrically with the Wilcoxon rank sum test. Differences in CT features were identified with multiple logistic regression analysis.

RESULTS

The coarseness of fibrosis was similar in patients with SSc and idiopathic NSIP but strikingly different between patients with SSc (median coarseness score, 5.5; range, 0.0-13.3) and IPF (median coarseness score, 8.8; range, 2.5-15.0) (P <.001). The proportion of ground-glass opacification at CT was similar in patients with SSc and idiopathic NSIP but differed significantly between patients with SSc (median proportion, 49.9%; range, 0.0%-100.0%) and IPF (median proportion, 23.5%; range, 0.0%-97.2%) (P <.001). At logistic regression analysis, there were no differences in the CT features between patients with SSc and those with NSIP after controlling for age, disease extent, and the percentage predicted forced vital capacity and carbon monoxide diffusing capacity.

CONCLUSION

Interstitial lung disease in patients with SSc is less extensive, less coarse, and characterized by a greater proportion of ground-glass opacification than that in patients with IPF. The CT features of lung disease in patients with SSc closely resemble those in patients with idiopathic NSIP.

The idiopathic interstitial pneumonias

This review includes the seven idiopathic interstitial pneumonias defined by The American Thoracic Society and The European Respiratory Society 2002 publication. Idiopathic pulmonary fibrosis is the clinical term for usual interstitial pneumonia. The radiologic pattern includes basal and subpleural ground glass and reticular opacities and honeycomb lung. Nonspecific interstitial pneumonia is characterized with a radiologic pattern of subpleural and basal ground glass and reticular opacities. Cryptogenic organizing pneumonia is manifest radiologically by peribronchial ground glass opacities and subpleural consolidation. Acute interstitial pneumonia is the clinical term for idiopathic diffuse alveolar damage and the exudative phase is characterized radiologically with diffuse ground glass opacification and dependent consolidation with the additional feature of lung architectural distortion in the organizing phase. Respiratory bronchiolitis associated interstitial lung disease manifests as centrilobular ground glass opacities on CT. Desquamative interstitial pneumonia is characterized by ground glass opacities with lower zone predominance on CT. Lymphoid interstitial pneumonia manifests by ground glass opacities and nodular interlobular septal thickening on CT. The diagnosis of an IIP should be rendered ideally only after all clinicoradiologic-pathologic data have been reviewed.

CT-histologic correlation of the ATS/ERS 2002 classification of idiopathic interstitial pneumonias

The American Thoracic Society and the European Respiratory Society 2002 classification defines the histologic patterns that provide the basis for a clinico-radiologic-pathologic diagnosis of an idiopathic interstitial pneumonia. Idiopathic pulmonary fibrosis is the clinical term for usual interstitial pneumonia, the characteristic histologic pattern is interstitial fibrosis with temporal heterogeneity, and the radiologic pattern is basal and subpleural areas of ground-glass and reticular attenuation and honeycomb pattern. Nonspecific interstitial pneumonia has cellular or fibrosing patterns of chronic inflammation with temporal homogeneity; the radiologic pattern is subpleural and basal areas of ground-glass and reticular attenuation. Lymphoid interstitial pneumonia results from lymphocyte interstitial infiltration; CT demonstrates ground-glass attenuation and nodular interlobular septal thickening. Respiratory bronchiolitis-associated interstitial lung disease is characterized by bronchiolocentric alveolar macrophage accumulation; CT shows centrilobular ground-glass attenuation. Desquamative interstitial pneumonia is characterized by alveolar macrophage accumulation with predominantly lower zone ground-glass attenuation seen on CT scans. Cryptogenic organizing pneumonia is characterized radiologically by peribronchial ground-glass attenuation and subpleural consolidation. Acute interstitial pneumonia is the clinical term for idiopathic diffuse alveolar damage; the exudative phase is characterized radiologically by diffuse ground-glass attenuation and dependent consolidation, with the additional feature of lung architectural distortion in the organizing phase. Ideally, diagnosis of an idiopathic interstitial pneumonia should be rendered only after all clinico-radiologic-pathologic data have been reviewed.

Idiopathic pulmonary fibrosis: a composite physiologic index derived from disease extent observed by computed tomography

In idiopathic pulmonary fibrosis, the quantitation of disease severity using pulmonary function tests is often confounded by emphysema. We have identified the composite physiologic index (CPI) most closely reflecting the morphologic extent of pulmonary fibrosis. Consecutive patients with a clinical/computed tomography (CT) diagnosis of idiopathic pulmonary fibrosis (n = 212) were divided into group I (n = 106) and group II (n = 106). The CPI was derived in group I (by fitting pulmonary function tests against disease extent on CT) and was tested in Group II. The formula for the CPI was as follows: extent of disease on CT = 91.0 - (0.65 x percent predicted diffusing capacity for carbon monoxide [DLCO]) - (0.53 x percent predicted FVC) + (0.34 x percent predicted FEV1). In group II, the CPI correlated more strongly with disease extent on CT (r2 = 0.51) than the individual pulmonary function test (DLCO the highest value, r2 = 0.38). A subanalysis demonstrated that the better fit of the CPI was ascribable to a correction of the confounding effects of emphysema. Mortality was predicted more accurately by the CPI than by a pulmonary function test in all clinical subgroups, including a separate cohort of 36 patients with histologically proven usual interstitial pneumonia (CPI, p < 0.0005; FVC, p = 0.002; PO2, p = 0.002). In conclusion, a new CPI, derived against CT and validated using split sample testing, is a more accurate prognostic determinant in usual interstitial pneumonia than an individual pulmonary function test.

Interstitial vascularity in fibrosing alveolitis

The aim of this study was to evaluate interstitial vascularity in cryptogenic fibrosing alveolitis (CFA) and in fibrosing alveolitis associated with systemic sclerosis (FASSc). Open lung biopsies from eight patients with CFA, nine patients with FASSc, and normal lung from 12 patients undergoing surgery for lung cancer were studied. Markers for endothelial cells (CD34) and cell proliferation (proliferating cell nuclear antigen) were localized by sequential immunohistochemistry and quantified using computer-assisted analysis. Vascular distribution was evaluated at increasing distances (up to 160 microm) from the airspaces. Vessel density was markedly reduced in both FASSc (3.9%) and in CFA (4.5%) compared with control samples (20.4%, p < 0.0001). The percentage of tissue occupied by vessels decreased with increasing distance from alveoli in control samples but not in CFA or FASSc samples. Endothelial cell proliferation indices were increased in FASSc but not in CFA, compared with control samples (p = 0.006). In conclusion, there is net vascular ablation and redistribution of blood vessels in areas of interstitial thickening in both CFA and FASSc, which may contribute to gas exchange impairment.

High-resolution CT of idiopathic interstitial pneumonias

Important recent changes have occurred in our understanding of the IIPs. IPF (characterized histologically as UIP) is recognized as a progressive disease with a relatively poor prognosis, and with a characteristic CT appearance. The radiologist must be able to distinguish between UIP and the other IIPs. Complications of IPF include accelerated progression, lung cancer, and secondary infection. NSIP has a better prognosis than IPF, and has ground-glass attenuation as its salient CT feature. COP (formerly known as BOOP) is included as an IIP because its clinical, physiologic, and imaging features overlap with those of the other IIPs. It is characterized on CT by consolidation and ground-glass attenuation. AIP is the idiopathic form of ARDS. LIP and DIP are less common IIPs, both characterized by ground-glass attenuation.

High-resolution computed tomography in the evaluation of fibrosing alveolitis

High-resolution computed tomography (HRCT) is now widely used in the investigation of patients with suspected or known diffuse lung disease. This article reviews some of the technical aspects of HRCT and the pathologic considerations that should be appreciated in the context of diagnosing fibrosing alveolitis. The precise quantitation of disease extent and characterization of disease pattern on HRCT has been used to provide new insights about the prognosis and pathophysiology of fibrosing lung disease.

[Pulmonary involvement in systemic scleroderma. Part I. Chronic fibrosing interstitial lung disease]

INTRODUCTION

Chronic pulmonary interstitial fibrosis is the most frequent respiratory manifestation in systemic sclerosis, occurring in 80% of cases. It remains a severe complication of the disease and is the primary cause of mortality related to respiratory insufficiency in 20 to 60% of cases.

CURRENT KNOWLEDGE AND KEY POINTS

The date of onset of interstitial lung disease remains undetermined, and only in rare cases does it reveal the presence of systemic sclerosis. The clinical signs are only observable at a later stage, when at least 50% of the lung parenchyma is affected. The methods of choice adopted for early diagnosis of this disease are high resolution computed tomography and pulmonary functional investigations; they should be carried out during the preliminary investigation and at follow-up once a year. Moreover, high resolution computed tomography also provides prognostic data, for there is a correlation between the type of lesion and its severity as determined by high resolution computed tomography and by histological findings. The value of other methods of investigation, in particular bronchoalveolar lavage, has not yet been clearly established. The association of cyclophosphamide and corticoids is currently being evaluated (indications, administration modalities, duration), and this combination may be the most effective treatment.

FUTURE PROSPECTS AND PROJECTS

Interstitial lung disease is one of the major causes of morbidity and mortality in systemic sclerosis. Early diagnosis and management of this disease is therefore of utmost importance.

Bronchoalveolar lavage cellularity: lone cryptogenic fibrosing alveolitis compared with the fibrosing alveolitis of systemic sclerosis

Lone cryptogenic fibrosing alveolitis (CFA) is histologically identical to fibrosing alveolitis associated with systemic sclerosis (FASSc), but it has a much worse prognosis after matching for disease severity at presentation. The aims of this study were to gain insights into possible pathogenetic mechanisms contributing to this prognostic difference, by comparing bronchoalveolar lavage (BAL) cellularity in the two diseases, and to evaluate the relationships between BAL findings and the regional and global extent of disease, quantified by thin-section computed tomography (CT) and lung function indices. Patients with CFA were distinguished by more extensive fibrosing alveolitis on CT (p < 0.02) and by higher counts of neutrophils (total per ml, p < 0.02; percentage p < 0.03) and eosinophils (total per ml, p < 0.002; percentages, p < 0.02) in BAL fluid. After adjustment for functional and morphologic measures of disease extent, eosinophil percentages and total counts were increased in CFA (p < 0.05 in all 12 multivariate models), but they were not independently related to regional or global disease severity. Neutrophil percentages and total counts were virtually identical in CFA and FASSc in disease of comparable severity, and they increased with increasingly extensive lobar disease and global disease, as judged by CT, p < 0.0005 in all analyses. Neutrophil levels were more closely linked to the extent of disease on CT than to the severity of functional impairment, on univariate and multivariate analysis. The higher BAL eosinophil levels seen in CFA, compared with those seen in FASSc, after adjustment for disease extent, indicate that an eosinophilic influx may be linked to the pathogenesis of fibrosing alveolitis. By contrast, BAL neutrophil levels increase with increasingly extensive disease on CT, but they do not differ independently between CFA and FASSc, suggesting that neutrophil degradation products are unlikely to account for the excess mortality in CFA, compared with that in FASSc.