Concentration of Serum Vascular Endothelial Growth Factor (VEGF-D) and Its Correlation with Functional and Clinical Parameters in Patients with Lymphangioleiomyomatosis from a Brazilian Reference Center.

INTRODUCTION: Serum vascular endothelial growth factor-D (VEGF-D) is a lymphangiogenic growth factor that is considered a valuable tool in the diagnosis of lymphangioleiomyomatosis (LAM). Previous studies have reported a wide variability in VEGF-D serum levels in LAM patients and it seems to be associated with pulmonary impairment and lymphatic involvement. METHODS: We conducted a cross-sectional study from 2009 to 2017 that evaluated VEGF-D serum levels in a cohort of LAM patients who were never treated with mTOR inhibitors and compared them to healthy age-matched volunteers. Clinical and functional parameters were assessed and correlated with their respective serum VEGF-D levels. RESULTS: One hundred and four patients were included in the analysis. Serum VEGF-D levels were higher in LAM patients compared to healthy controls: 796 (404-1588) versus 162 (117-232) pg/mL, respectively (p < 0.001). Patients with tuberous sclerosis complex-LAM, TSC-LAM (20%), had higher levels of VEGF-D when compared to patients with sporadic LAM (80%) [1005 (641-2732) vs. 772 (370-1383), p = 0.05]. Serum VEGF-D levels were weakly correlated with DLCO (r = - 0.26, p = 0.001) and lymphatic involvement was more frequent in those with serum VEGF-D levels equal or above 800 pg/mL (35% vs. 13%, p = 0.02). CONCLUSIONS: In LAM, serum VEGF-D is weakly associated with lung function impairment and strongly associated with lymphatic involvement. VEGF-D is validated for use in Brazilian patients with LAM whose characteristics must be accounted for when evaluating their serum VEGF-D levels.

Evaluation of the extent of pulmonary cysts and their association with functional variables and serum markers in lymphangioleiomyomatosis (LAM).

PURPOSE: Although computed tomography (CT) has been used previously to assess disease severity in lymphangioleiomyomatosis (LAM), the associations between the extent of pulmonary cysts on CT and six-minute walk test (6MWT), matrix metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF-D) are not well established. We performed a cross-sectional study to quantify the extent of pulmonary cysts in CT and to establish their correlations with pulmonary function tests (PFTs), 6MWT results, including a composite index (desaturation-distance ratio, DDR), and levels of VEGF-D and MMPs in LAM. METHODS: Twenty-three LAM patients underwent CT scanning to automatically quantify the extent of pulmonary cysts and performed PFTs and 6MWT. Serum levels of MMP-2, MMP-9, and VEGF-D were also measured. RESULTS: The severity of pulmonary cystic involvement was mild (the extent of cysts was 6.8 %) and correlated best with FEV1/FVC (r = -0.84), residual volume (r = 0.66), DLCO (r = -0.82), the DDR index (r = 0.77), and desaturation during the 6MWT (r = -0.81). There was a weak correlation with VEGF-D (r = 0.45), but no association was found with MMP-2 and MMP-9. CONCLUSIONS: The severity of pulmonary cystic involvement was mild in this sample of LAM patients and correlated best with airway obstruction, air trapping, reduced DLCO, the DDR index, and desaturation during the 6MWT. Serum VEGF-D cannot be completely defined as a valuable marker of disease severity and there may be a mechanism independent of MMPs to explain the formation of pulmonary cysts.

Quantitative CT Analysis in Chronic Hypersensitivity Pneumonitis: A Convolutional Neural Network Approach.

RATIONALE AND OBJECTIVES: Chronic hypersensitivity pneumonitis (cHP) is a heterogeneous condition, where both small airway involvement and fibrosis may simultaneously occur. Computer-aided analysis of CT lung imaging is increasingly used to improve tissue characterization in interstitial lung diseases (ILD), quantifying disease extension, and progression. We aimed to quantify via a convolutional neural network (CNN) method the extent of different pathological classes in cHP, and to determine their correlation to pulmonary function tests (PFTs) and mosaic attenuation pattern. MATERIALS AND METHODS: The extension of six textural features, including consolidation (C), ground glass opacity (GGO), fibrosis (F), low attenuation areas (LAA), reticulation (R) and healthy regions (H), was quantified in 27 cHP patients (age: 56 ± 11.5 years, forced vital capacity [FVC]% = 57 ± 17) acquired at full-inspiration via HRCT. Each class extent was correlated to PFTs and to mosaic attenuation pattern. RESULTS: H showed a positive correlation with FVC%, FEV1% (forced expiratory volume), total lung capacity%, and diffusion of carbon monoxide (DLCO)% (r = 0.74, r = 0.78, r = 0.73, and r = 0.60, respectively, p < 0.001). GGO, R and C negatively correlated with FVC% and FEV1% with the highest correlations found for R (r = -0.44, and r = -0.46 respectively, p < 0.05); F negatively correlated with DLCO% (r = -0.42, p < 0.05). Patients with mosaic attenuation pattern had significantly more H (p = 0.04) and lower R (p = 0.02) and C (p = 0.0009) areas, and more preserved lung function indices (higher FVC%; p = 0.04 and DLCO%; p = 0.05), but did not show more air trapping in lung function tests. CONCLUSION: CNN quantification of pathological tissue extent in cHP improves its characterization and shows correlation with PFTs. LAA can be overestimated by visual, qualitative CT assessment and mosaic attenuation pattern areas in cHP represents patchy ILD rather than small-airways disease.

A Convolutional Neural Network Approach to Quantify Lung Disease Progression in Patients with Fibrotic Hypersensitivity Pneumonitis (HP).

Rationale and Objectives To evaluate associations between longitudinal changes of quantitative CT parameters and spirometry in patients with fibrotic hypersensitivity pneumonitis (HP). Materials and Methods Serial CT images and spirometric data were retrospectively collected in a group of 25 fibrotic HP patients. Quantitative CT analysis included histogram parameters (median, interquartile range, skewness, and kurtosis) and a pretrained convolutional neural network (CNN)-based textural analysis, aimed at quantifying the extent of consolidation (C), fibrosis (F), ground-glass opacity (GGO), low attenuation areas (LAA) and healthy tissue (H). Results At baseline, FVC was 61(44-70) %pred. The median follow-up period was 1.4(0.8-3.2) years, with 3(2-4) visits per patient. Over the study, 8 patients (32%) showed a FVC decline of more than 5%, a significant worsening of all histogram parameters (p≤0.015) and an increased extent of fibrosis via CNN (p=0.038). On histogram analysis, decreased skewness and kurtosis were the parameters most strongly associated with worsened FVC (respectively, r2=0.63 and r2=0.54, p<0.001). On CNN classification, increased extent of fibrosis and consolidation were the measures most strongly correlated with FVC decline (r2=0.54 and r2=0.44, p<0.001). Conclusion CT histogram and CNN measurements provide sensitive measures of functional changes in fibrotic HP patients over time. Increased fibrosis was associated with FVC decline, providing index of disease progression. CNN may help improve fibrotic HP follow-up, providing a sensitive tool for progressive interstitial changes, which can potentially contribute to clinical decisions for individualizing disease management.

Natural history of incidental sporadic and tuberous sclerosis complex associated lymphangioleiomyomatosis.

Lymphangioleiomyiomatosis (LAM) is a rare disease affecting women in childbearing age. A sporadic form (S-LAM) affecting previously healthy women, and a form associated with Tuberous Sclerosis Complex (TSC-LAM) are described. Some data suggested that TSC-LAM could be a milder disease compared to S-LAM. To investigate whether the different disease behavior is real or due to overdiagnosis of screened TSC women, we compared the natural history of S-LAM and TSC-LAM in patients with incidental diagnosis. Clinical, and functional data from 52 patients (23 with S-LAM and 29 with TSC-LAM) were analysed. At diagnosis functional impairment was mild without differences between groups [FEV1 % pred was 97% (88-105) and 94% (82-106) in TSC-LAM and S-LAM, respectively, p = 0.125]. Patients with S-LAM had less renal angiomyolipoma, and lower VEGF-D serum levels than TSC-LAM. There was no difference in the baseline extent of pulmonary cysts on CT scan and no difference in yearly rate of functional decline between TSC-LAM, and S-LAM patients [e.g. yearly rate of decline of FEV1 % pred was -0.51 (-1.59-2.24) and -0.90 (-1.92--0.42) in TSC-LAM and S-LAM, respectively, p = 0.265]. In conclusion, the natural history of TSC-LAM and S-LAM, when a potential selection bias due to screening in the latter group is balanced, is similar. Our study suggests that the prevalence of S-LAM can be significantly underestimated due to a tendency to diagnosis more frequently patients with more severe impairment, without identifying several ones with asymptomatic disease.

Forced Oscillation Technique and Small Airway Involvement in Chronic Hypersensitivity Pneumonitis.

OBJECTIVE: Hypersensitivity pneumonitis (HP) is an interstitial lung disease caused by the inhalation of specific organic antigens or low-molecular weight substances in genetically susceptible individuals. Although small airway involvement is prominent in patients with chronic HP, conventional pulmonary function tests (PFTs) are relatively insensitive to identify it. Thus, the authors aimed to evaluate resistance (R5) and reactance (X5) values at 5Hz on inspiration, expiration, and whole breath, as well as small airway resistance (R5-19) values using a forced oscillation technique (FOT) in patients with chronic HP, and their responses after bronchodilator. In addition, R5 and X5 values according to the presence or absence of mosaic attenuation on computed tomography (CT) were compared. METHODS: PFTs with plethysmography, diffusing capacity of the lungs for carbon monoxide (DLCO) and FOT measurements were performed pre-bronchodilator and post-bronchodilator. High-resolution CT was performed at the same visit, and classified according to the presence or absence of mosaic attenuation. R5 and X5 values were then compared according to the presence or absence of mosaic attenuation on CT. RESULTS: Twenty-eight patients with chronic HP (57.1% female; mean age, 56±11.5 years; mean forced vital capacity 57±17% predicted) were evaluated. All patients had low X5 values, reflecting lower lung compliance, and only three (8%) demonstrated elevated R5 (whole-breath) values. No patients exhibited bronchodilator response in R5, X5 and R5-19 values. In patients who exhibited greater extension of mosaic attenuation (n=11), R5 and X5 values could not discriminate those with a greater presence of these areas on CT. CONCLUSIONS: The results suggest that FOT does not help to additionally characterise concomitant small airway involvement in patients with chronic fibrotic HP who demonstrate restrictive ventilatory pattern in conventional PFTs. Nevertheless, FOT appeared to better characterise decreased lung compliance due to fibrosis through X5. Bronchodilator therapy did not appear to induce an acute response in chronic HP patients with restrictive disease. The precise role of FOT in subacute HP and obstructive chronic HP, therefore, must be evaluated.

Mechanisms of exercise limitation in patients with chronic hypersensitivity pneumonitis.

Small airway and interstitial pulmonary involvements are prominent in chronic hypersensitivity pneumonitis (cHP). However, their roles on exercise limitation and the relationship with functional lung tests have not been studied in detail. Our aim was to evaluate exercise performance and its determinants in cHP. We evaluated maximal cardiopulmonary exercise testing performance in 28 cHP patients (forced vital capacity 57±17% pred) and 18 healthy controls during cycling. Patients had reduced exercise performance with lower peak oxygen production (16.6 (12.3-19.98) mL·kg-1·min-1versus 25.1 (16.9-32.0), p=0.003), diminished breathing reserve (% maximal voluntary ventilation) (12 (6.4-34.8)% versus 41 (32.7-50.8)%, p<0.001) and hyperventilation (minute ventilation/carbon dioxide production slope 37±5 versus 31±4, p<0.001). All patients presented oxygen desaturation and augmented Borg dyspnoea scores (8 (5-10) versus 4 (1-7), p=0.004). The prevalence of dynamic hyperinflation was found in only 18% of patients. When comparing cHP patients with normal and low peak oxygen production (<84% pred, lower limit of normal), the latter exhibited a higher minute ventilation/carbon dioxide production slope (39±5.0 versus 34±3.6, p=0.004), lower tidal volume (0.84 (0.78-0.90) L versus 1.15 (0.97-1.67) L, p=0.002), and poorer physical functioning score on the Short form-36 health survey. Receiver operating characteristic curve analysis showed that reduced lung volumes (forced vital capacity %, total lung capacity % and diffusing capacity of the lung for carbon dioxide %) were high predictors of poor exercise capacity. Reduced exercise capacity was prevalent in patients because of ventilatory limitation and not due to dynamic hyperinflation. Reduced lung volumes were reliable predictors of lower performance during exercise.

Computed tomography in hypersensitivity pneumonitis: main findings, differential diagnosis and pitfalls.

INTRODUCTION: Hypersensitivity pneumonitis (HP) is a disease with variable clinical presentation in which inflammation in the lung parenchyma is caused by the inhalation of specific organic antigens or low molecular weight substances in genetically susceptible individuals. Alterations of the acute, subacute and chronic forms may eventually overlap, and the diagnosis based on temporality and presence of fibrosis (acute/inflammatory HP vs. chronic HP) seems to be more feasible and useful in clinical practice. Differential diagnosis of chronic HP with other interstitial fibrotic diseases is challenging due to the overlap of the clinical history, and the functional and imaging findings of these pathologies in the terminal stages. Areas covered: This article reviews the essential features of HP with emphasis on imaging features. Moreover, the main methodological limitations of high-resolution computed tomography (HRCT) interpretation are discussed, as well as new perspectives with volumetric quantitative CT analysis as a useful tool for retrieving detailed and accurate information from the lung parenchyma. Expert commentary: Mosaic attenuation is a prominent feature of this disease, but air trapping in chronic HP seems overestimated. Quantitative analysis has the potential to estimate the involvement of the pulmonary parenchyma more accurately and could correlate better with pulmonary function results.

Diffuse cystic lung diseases: differential diagnosis.

Diffuse cystic lung diseases are characterized by cysts in more than one lung lobe, the cysts originating from various mechanisms, including the expansion of the distal airspaces due to airway obstruction, necrosis of the airway walls, and parenchymal destruction. The progression of these diseases is variable. One essential tool in the evaluation of these diseases is HRCT, because it improves the characterization of pulmonary cysts (including their distribution, size, and length) and the evaluation of the regularity of the cyst wall, as well as the identification of associated pulmonary and extrapulmonary lesions. When combined with clinical and laboratory findings, HRCT is often sufficient for the etiological definition of diffuse lung cysts, avoiding the need for lung biopsy. The differential diagnoses of diffuse cystic lung diseases are myriad, including neoplastic, inflammatory, and infectious etiologies. Pulmonary Langerhans cell histiocytosis, lymphangioleiomyomatosis, lymphocytic interstitial pneumonia, and follicular bronchiolitis are the most common diseases that produce this CT pattern. However, new diseases have been included as potential determinants of this pattern. RESUMO As doenças pulmonares císticas difusas se caracterizam pela presença de cistos envolvendo mais de um lobo pulmonar, que se originam por diversos mecanismos, incluindo dilatação dos espaços aéreos distais por obstrução, necrose das paredes das vias aéreas e destruição do parênquima. Essas doenças apresentam evolução variável. A TCAR é fundamental na avaliação dessas doenças uma vez que permite uma melhor caracterização dos cistos pulmonares, incluindo sua distribuição, tamanho, extensão e regularidade das paredes, assim como a determinação de outras lesões pulmonares e extrapulmonares associadas. Frequentemente a TCAR é suficiente para a definição etiológica dos cistos pulmonares difusos, associada a achados clínicos e laboratoriais, sem a necessidade de realização de biópsia pulmonar. O diagnóstico diferencial das doenças pulmonares císticas difusas é extenso, incluindo etiologias neoplásicas, inflamatórias e infecciosas, sendo as mais frequentes determinantes desse padrão tomográfico a histiocitose pulmonar de células de Langerhans, a linfangioleiomiomatose, a pneumonia intersticial linfocitária e a bronquiolite folicular. Novas etiologias foram incluídas como potenciais determinantes desse padrão.

Cigarette smokers views on their habit and the causes of their illness following lung cancer diagnosis: a clinical-qualitative study.

CONTEXT AND OBJECTIVE: Lung cancer is the commonest malignant tumor and is increasing in incidence by 2% a year. In 90% of diagnosed cases, it is associated with tobacco product consumption. It is the greatest cause of mortality among cancer types in Brazil. Knowledge of patients psychological representations is needed for evaluating treatments and educating patients. The aim here was to interpret how smokers with lung cancer interpret the possible causes of their illness and to understand their perceptions regarding cigarette use. DESIGN AND SETTING: Clinical-qualitative study (exploratory, non-experimental) at the Pulmonary Disease Service, General Hospital, Universidade Estadual de Campinas. METHODS: An intentional small sample of cancer inpatients was recruited. The group was closed with 11 subjects, following attainment of data saturation from interviews. These interviews were semi-directed, with in-depth open-ended questions on interviewees observations, applied in a confidential setting using a tape recorder. Interviewees responses were categorized using qualitative content analysis and the results were assessed using interdisciplinary theoretical concepts, particularly from medical psychology. RESULTS: Six males and five females aged between 46 and 68 years who presented diverse clinical conditions were interviewed. CONCLUSIONS: A broader approach towards the psychological comprehension of such patients is needed, considering that cigarette consumption involves conscious and unconscious motivations, sociocultural and educational factors, the glamour of tobacco advertising, and problems with psychophysical dependence. Such an approach would avoid the perception among patients that the healthcare team are "inquisitors". This would lead to better adherence to treatment and better quality of life.

Association of Pulmonary Cysts and Nodules in a Young Female Patient.

A 27-year-old female patient was referred to our outpatient clinic with a 1-year history of shortness of breath when walking fast on level ground or when climbing stairs. Symptoms worsened after a second episode of spontaneous left pneumothorax, when a chest tube was placed in another hospital for complete lung expansion. During this hospitalization, an open lung biopsy was performed. There was no history of rhinorrhea, nasal congestion, cough, hemoptysis, wheezing, or expectoration.

Lung-dominant connective tissue disease among patients with interstitial lung disease: prevalence, functional stability, and common extrathoracic features.

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.

Combined pulmonary fibrosis and emphysema: an increasingly recognized condition.

Combined pulmonary fibrosis and emphysema (CPFE) has been increasingly recognized in the literature. Patients with CPFE are usually heavy smokers or former smokers with concomitant lower lobe fibrosis and upper lobe emphysema on chest HRCT scans. They commonly present with severe breathlessness and low DLCO, despite spirometry showing relatively preserved lung volumes. Moderate to severe pulmonary arterial hypertension is common in such patients, who are also at an increased risk of developing lung cancer. Unfortunately, there is currently no effective treatment for CPFE. In this review, we discuss the current knowledge of the pathogenesis, clinical characteristics, and prognostic factors of CPFE. Given that most of the published data on CPFE are based on retrospective analysis, more studies are needed in order to address the role of emphysema and its subtypes; the progression of fibrosis/emphysema and its correlation with inflammation; treatment options; and prognosis.

Adalimumab-induced acute interstitial lung disease in a patient with rheumatoid arthritis.

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.

Clinical course and characterisation of lymphangioleiomyomatosis in a Brazilian reference centre.

BACKGROUND AND OBJECTIVE: Lymphangioleiomyomatosis (LAM) is a rare disease that promotes pulmonary cystic destruction and impairs pulmonary function. We aim to describe features and clinical course of LAM patients from Brazil. METHODS: We described the clinical and functional features, performance in six minute walk test (6MWT), management details, survival and clinical course of 84 LAM patients followed in a Brazilian reference centre. RESULTS: All subjects were women, the average age at onset of symptoms was 38 years, and the average at diagnosis was 42 years. The major symptoms during the course of the disease were dyspnoea and pneumothorax. The patients experienced impaired quality of life, with worse scores in the physical and emotional domains. The most common abnormalities in pulmonary function tests were an obstructive pattern and reduced diffusion capacity, whereas a quarter of the patients had normal spirometric results. In the 6MWT, although patients had preserved exercise capacity, more than half of the patients had significant desaturation. Hormonal blockage and doxycycline were the most common treatment modalities employed in our patients. The survival probability from diagnosis was 90% at 5 years, whereas the mean annual rate of decline in FEV1 was 60 ± 78 mL. CONCLUSIONS: Clinical and functional features of the LAM patients from our centre are similar to those from other countries. Our sample showed preserved exercise capacity, with desaturation in the 6MWT, and impaired quality of life. Survival was similar, whereas the annual rate of decline of FEV1 was slightly lower than in recent studies.

Transient lymphadenopathy secondary to nephrotic syndrome.

Mediastinal lymphadenomegaly secondary to hypervolemia is an underdiagnosed tomographic finding. Herein we describe, in a patient with normal cardiac function, findings of pulmonary congestion associated to lymph node enlargement. The nephrotic syndrome causing hypoalbuminemia, low plasma colloid osmotic pressure and augmented transcapillary fluid leakage was the probable cause of the radiological findings.

Diffuse cystic lung diseases: differential diagnosis / Doenças pulmonares císticas difusas: diagnóstico diferencial

ABSTRACT Diffuse cystic lung diseases are characterized by cysts in more than one lung lobe, the cysts originating from various mechanisms, including the expansion of the distal airspaces due to airway obstruction, necrosis of the airway walls, and parenchymal destruction. The progression of these diseases is variable. One essential tool in the evaluation of these diseases is HRCT, because it improves the characterization of pulmonary cysts (including their distribution, size, and length) and the evaluation of the regularity of the cyst wall, as well as the identification of associated pulmonary and extrapulmonary lesions. When combined with clinical and laboratory findings, HRCT is often sufficient for the etiological definition of diffuse lung cysts, avoiding the need for lung biopsy. The differential diagnoses of diffuse cystic lung diseases are myriad, including neoplastic, inflammatory, and infectious etiologies. Pulmonary Langerhans cell histiocytosis, lymphangioleiomyomatosis, lymphocytic interstitial pneumonia, and follicular bronchiolitis are the most common diseases that produce this CT pattern. However, new diseases have been included as potential determinants of this pattern.

RESUMO As doenças pulmonares císticas difusas se caracterizam pela presença de cistos envolvendo mais de um lobo pulmonar, que se originam por diversos mecanismos, incluindo dilatação dos espaços aéreos distais por obstrução, necrose das paredes das vias aéreas e destruição do parênquima. Essas doenças apresentam evolução variável. A TCAR é fundamental na avaliação dessas doenças uma vez que permite uma melhor caracterização dos cistos pulmonares, incluindo sua distribuição, tamanho, extensão e regularidade das paredes, assim como a determinação de outras lesões pulmonares e extrapulmonares associadas. Frequentemente a TCAR é suficiente para a definição etiológica dos cistos pulmonares difusos, associada a achados clínicos e laboratoriais, sem a necessidade de realização de biópsia pulmonar. O diagnóstico diferencial das doenças pulmonares císticas difusas é extenso, incluindo etiologias neoplásicas, inflamatórias e infecciosas, sendo as mais frequentes determinantes desse padrão tomográfico a histiocitose pulmonar de células de Langerhans, a linfangioleiomiomatose, a pneumonia intersticial linfocitária e a bronquiolite folicular. Novas etiologias foram incluídas como potenciais determinantes desse padrão.