Differential diagnosis of pulmonary sarcoidosis: a review.

Diagnosing pulmonary sarcoidosis raises challenges due to both the absence of a specific diagnostic criterion and the varied presentations capable of mimicking many other conditions. The aim of this review is to help non-sarcoidosis experts establish optimal differential-diagnosis strategies tailored to each situation. Alternative granulomatous diseases that must be ruled out include infections (notably tuberculosis, nontuberculous mycobacterial infections, and histoplasmosis), chronic beryllium disease, hypersensitivity pneumonitis, granulomatous talcosis, drug-induced granulomatosis (notably due to TNF-a antagonists, immune checkpoint inhibitors, targeted therapies, and interferons), immune deficiencies, genetic disorders (Blau syndrome), Crohn's disease, granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, and malignancy-associated granulomatosis. Ruling out lymphoproliferative disorders may also be very challenging before obtaining typical biopsy specimen. The first step is an assessment of epidemiological factors, notably the incidence of sarcoidosis and of alternative diagnoses; exposure to risk factors (e.g., infectious, occupational, and environmental agents); and exposure to drugs taken for therapeutic or recreational purposes. The clinical history, physical examination and, above all, chest computed tomography indicate which differential diagnoses are most likely, thereby guiding the choice of subsequent investigations (e.g., microbiological investigations, lymphocyte proliferation tests with metals, autoantibody assays, and genetic tests). The goal is to rule out all diagnoses other than sarcoidosis that are consistent with the clinical situation. Chest computed tomography findings, from common to rare and from typical to atypical, are described for sarcoidosis and the alternatives. The pathology of granulomas and associated lesions is discussed and diagnostically helpful stains specified. In some patients, the definite diagnosis may require the continuous gathering of information during follow-up. Diseases that often closely mimic sarcoidosis include chronic beryllium disease and drug-induced granulomatosis. Tuberculosis rarely resembles sarcoidosis but is a leading differential diagnosis in regions of high tuberculosis endemicity.

Imaging features and differential diagnoses of non-neoplastic diffuse mediastinal diseases.

Acute or chronic non-neoplastic diffuse mediastinal diseases have multiple causes, degrees of severity, and a wide range of management. Some situations require emergency care while others do not need specific treatment. Although the diagnosis may be suspected on chest X-ray, it is mainly based on CT. A delayed recognition is not uncommonly observed. Some findings may prompt the radiologist to look for specific associated injuries or lesions.This pictorial review will successively describe the various non-neoplastic causes of diffuse mediastinal diseases with their typical findings and major differentials.First, pneumomediastinum that can be provoked by extra- or intra-thoracic triggers requires the knowledge of patient's history or recent occurrences. Absence of any usual etiological factor should raise suspicion of cocaine inhalation in young individuals.Next, acute mediastinitis may be related to post-operative complications, esophageal perforation, or contiguous spread of odontogenic or retropharyngeal infections. The former diagnosis is not an easy task in the early stage, owing to the similarities of imaging findings with those of normal post-operative appearance during the first 2-3 weeks.Finally, fibrosing mediastinitis that is linked to an excessive fibrotic reaction in the mediastinum with variable compromise of mediastinal structures, in particular vascular and airway ones. Differential diagnosis includes tumoral and inflammatory infiltrations of the mediastinum.

Chest computed tomography findings for a cohort of children with pulmonary Langerhans cell histiocytosis.

OBJECTIVE: This study was undertaken to describe the spectrum of lung computed-tomography (CT) findings in children with pulmonary Langerhans cell histiocytosis (PLCH) and to evaluate for this population the CT-scan nodule and cyst scores proposed by adult pulmonologists at diagnosis and during follow-up. METHODS: Among 175 children with PLCH identified in the French national population-based Langerhans cell histiocytosis cohort, 60 were retrospectively selected by the availability of CT for a central review by three pediatric radiologists. These 60 patients are representative of childhood PLCH for almost all clinical aspects, except a lower percentage of risk organ involvement (38% vs 54%; P = 0.05). RESULTS: The 60 children's chest CT scans (n = 218) were reviewed. At diagnosis, 63% of them had nodules, 53% had cysts, and 29% had both. The percentages of patients with nodules or cysts increased from diagnosis to peak disease activity, respectively, from 63% to 73% and from 53% to 66%. The costophrenic angle was involved in 71%. Patients with pneumothorax (25%) had a higher median cyst score. Alveolar consolidation was observed in 34%. Patients with low CT-scan nodule and cyst scores had no long-term pulmonary sequelae. CONCLUSIONS: Well-known characteristics of adult PLCH (nodules and cysts) were observed in children. The chest CT scores proposed by adult pulmonologists could easily be applied to childhood PLCH. Lesions in children, unlike those in adults, are frequently located near the costophrenic angles. Alveolar consolidation might be considered an atypical feature of childhood PLCH.

Prevalence and incidence of interstitial lung diseases in a multi-ethnic county of Greater Paris.

The objective of the study was to estimate the prevalence and incidence of interstitial lung diseases (ILDs) in Seine-Saint-Denis, a multi-ethnic county of Greater Paris, France.Patients with ILDs were identified between January and December 2012 by using several sources; all potentially involved medical specialists from public and private hospitals, community-based pulmonologists and general practitioners, and the Social Security system. Diagnoses were validated centrally by an expert multidisciplinary discussion.1170 ILD cases were reported (crude overall prevalence: 97.9/105 and incidence: 19.4/105/year). In the 848 reviewed cases, the most prevalent diagnoses were sarcoidosis (42.6%), connective tissue diseases associated ILDs (CTDs-ILDs) (16%), idiopathic pulmonary fibrosis (IPF) (11.6%), and occupational ILDs (5.0%), which corresponded to a crude prevalence of 30.2/105 for sarcoidosis, 12.1/105 for CTDs-ILDs and 8.2/105 for IPF. The prevalence of fibrotic idiopathic interstitial pneumonias, merging IPF, nonspecific interstitial pneumonia and cases registered with code J84.1 was 16.34/105 An adjusted multinomial model demonstrated an increased risk of sarcoidosis in North Africans and Afro-Caribbeans and of CTDs-ILDs in Afro-Caribbeans, compared to that in Europeans.This study, with a comprehensive recruitment and stringent diagnostic criteria, emphasises the importance of secondary ILDs, particularly CTDs-ILDs and the relatively low prevalence of IPF, and confirms that sarcoidosis is a rare disease in France.

High-resolution computed tomography to differentiate chronic diffuse infiltrative lung diseases with chronic multifocal consolidation patterns using logical analysis of data.

BACKGROUND: Chronic lung consolidation has a limited number of differential diagnoses requiring distinct managements. The aim of the study was to investigate how logical analysis of data (LAD) can support their diagnosis at HRCT (high-resolution computed tomography). METHODS: One hundred twenty-four patients were retrospectively included and classified into 8 diagnosis categories: sarcoidosis (n=35), connective tissue disease (n=21), adenocarcinoma (n=17), lymphoma (n=13), cryptogenic organizing pneumonia (n=11), drug-induced lung disease (n=9), chronic eosinophilic pneumonia (n =7) and miscellaneous (n=11). First, we investigated the patterns and models (association of patterns characterizing a disease) built-up by the LAD from combinations of HRCT attributes (n=51). Second, data were recomputed by adding simple clinical attributes (n=14) to the analysis. Third, cluster analysis was performed to explain LAD failures. RESULTS: HRCT models reached a sensitivity >80% and a specificity >90% for adenocarcinoma and chronic eosinophilic pneumonia. The same thresholds were obtained for sarcoidosis, connective tissue disease, and drug-induced lung diseases when clinical attributes were added to HRCT. LAD failed to provide a satisfactory model for lymphoma and cryptogenic organizing pneumonia, with overlap between both diseases shown on cluster analysis. CONCLUSION: LAD provides relevant models that can be used as a diagnosis support for the radiologist. It highlights the need to add clinical data in the analysis due to frequent overlap between diseases at HRCT.

Delineation in thoracic oncology: a prospective study of the effect of training on contour variability and dosimetric consequences.

INTRODUCTION: As part of French residents' radiotherapy training, delineation workstations were available at a national teaching course. We report a prospective comparative study of a non small cell lung cancer (NSCLC) case delineated by 120 residents before and after a radioanatomy/radiotherapy lecture. MATERIALS AND METHODS: The case of a patient with right upper lobe non small cell lung cancer (NSCLC) was provided for delineation to 32 groups of residents before and after a radiation therapy lecture about thoracic delineation. GTV, CTV and PTV was asked to each group. In a second step, the GTV, CTV and PTV were compared with those of 9 groups of senior physicians. Finally the consequences for treatment planning between each group before and after the course were explored. RESULTS: The expert's average GTV, CTV and PTV were 89.1 cm3, 242.3 cm3 and 293.9 cm3 respectively. For residents, those volumes were 103.4 cm3, 242.3 cm3 and 457.9 cm3 before teaching, compared to 99.5 cm3, 224.2 cm3 and 412.5 cm3 after teaching. The overlap (OV) and kappa (KI) indices before and after education were respectively 0.58 and 0.73. Compared to senior physicians, OV and KI indices were lower in the residents group (p = 0.039 and p = 0.043). An increased dose to the lung is noted for the residents' dosimetry compared to the experts' (V20: 23.2% versus 36.5%) due to the larger PTV delineated. No significant difference was observed for other organs at risk. CONCLUSION: There were no significant differences for the delineation of the GTV and CTV before and after the course, although the differences tended to decrease after the course. The good initial quality of the contours could explain the lack of difference. V20 for lung was higher in the residents group compared to the experts group (23.2% vs 36.5%). No other treatment planning consequences were observed for other critical organs.

Progression of idiopathic pulmonary fibrosis: lessons from asymmetrical disease.

BACKGROUND: In idiopathic pulmonary fibrosis (IPF) the distribution and spatial-temporal progression of fibrotic changes may be influenced by general or locoregional conditions. From this perspective, patients with asymmetrical disease (AIPF) may be unique. METHODS: This retrospective study included 32 patients (26 men, mean ± SD age 69 ± 7 years) with AIPF, as defined by an asymmetry ratio (most affected--least affected fibrosis score)/(most affected + least affected fibrosis score) >0.2. The global fibrosis score was the average of the right and left scores. Patients with AIPF were compared with 64 matched controls with symmetrical IPF. RESULTS: Patients with AIPF did not differ from controls in global fibrosis score and forced vital capacity, but carbon monoxide transfer factor was less decreased (52 ± 19% vs 43 ± 13%, p=0.009). The rate of gastro-oesophageal reflux and acute exacerbations was significantly higher in patients with AIPF (62.5% vs 31.3%, p=0.006 and 46.9% vs 17.2%, p=0.004, respectively). In patients with AIPF the right side was more likely to be involved (62.5%); the median asymmetry ratio was 0.5 (range 0.24-1). Although the global fibrosis score worsened significantly in all 23 patients with AIPF with serial high-resolution CT scans (p<0.0001), pulmonary fibrosis remained asymmetrical in all except three. During follow-up, 15 patients with AIPF experienced 18 acute exacerbations. The first episode was virtually unilateral, occurring in the most affected lung in 10 patients (66.7%). Survival was similar between patients with AIPF and controls. CONCLUSION: AIPF may be related to locoregional factors including gastro-oesophageal reflux which may be responsible for both disease expansion and the occurrence of acute exacerbations.

[Imaging of fibrosing interstitial pneumonias]. / Imagerie des pneumonies interstitielles fibrosantes.

The term fibrosing interstitial pneumonia covers several distinct entities, including usual interstitial pneumonia, non specific interstitial pneumonia acute interstitial pneumonia, desquamative interstitial pneumonia, and lymphoid interstitial pneumonia. Because of its very poor prognosis and different management, usual interstitial pneumonia, and particularly idiopathic forms (idiopathic pulmonary fibrosis), must be distinguished from other forms of interstitial pneumonia. The diagnosis of idiopathic pulmonary fibrosis is based on the CT or pathologic criteria of usual interstitial pneumonia, in the absence of asbestosis, chronic hypersensitive pneumonitis, and collagen vascular disease. In more than 50% of cases, idiopathic pulmonary fibrosis may be confidently diagnosed on the basis of CT findings, showing reticular opacities and honeycombing with a predominantly basal and subpleural distribution, without nodules, extensive consolidation or ground-glass opacities. Surgical biopsy may be necessary when these features are absent, given the overlap of CT findings between the different forms of interstitial pneumonia. In such cases, specific diagnosis of interstitial lung disease is based on a combination of clinical, radiological and histopathological findings.

[Imaging findings in intersitial lung diseases]. / Imagerie des pneumopathies infiltrantes diffuses.

Subacute and chronic diffuse interstitial lung diseases Computed tomography (CT) plays an important role in all stages of management: positive diagnosis, etiological diagnosis, evaluation of lesions, ongoing monitoring, screening for complications, and prognosis. The etiological diagnosis is based on the imaging and analysis of patterns or groups of basic lesions often characteristics of a disease. Assessment of the images, the patient history, and the epidemiologic, clinical, laboratory, functional and cytologic data generally make it possible to reach a diagnosis. A pulmonary biopsy is rarely necessary. Acute diffuse interstitial lung diseases In the absence of an obvious clinical direction, CT, electrocardiography, and echocardiography are the first-line examinations to identify or rule out cardiogenic edema. CT can be used to guide bronchoalveolar lavage (BAL), widely used when the patient's respiratory condition permits. BAL can provide a diagnosis of diverse infections or help determine the cytologic type of alveolitis. CT also makes it possible to evaluate the lesions and plays a role in assessing severity. It makes it possible to choose the best sampling method and in principle directs sampling towards the most useful areas. It allows monitoring of disease course, screening of some complications, and precise localizing of tubes, drains, and catheters. Finally, it is used to assess the sequelae.

ANCA-associated lung fibrosis: analysis of 17 patients.

In this retrospective study, we analyzed 17 patients presenting with pulmonary fibrosis and a positive ANCA testing. This group was compared with a control group of 12 patients with IPF and negative ANCA testing. Patients were 15 males and 2 females, with a mean age of 66 years. Eight patients were past smokers, 3 current smokers and 6 non-smokers. Lung function tests at diagnosis were as follows (% predicted): total lung capacity 73%+/-18, vital capacity 82%+/-23, forced expiratory volume in 1 s (FEV(1)) 88%+/-24, carbon monoxide diffusion capacity of the lung 49%+/-2 (% predicted). Bronchoalveolar lavage results showed an increased cellularity with increased neutrophils counts. High resolution computed tomography of the chest showed prominent fibrosis with some degree of ground-glass attenuation in all patients. These characteristics were similar to the control group. Microscopic polyangiitis (MPA) was a major complicating event in ANCA-positive patients, occurring in 7 patients (anti-myeloperoxidase specificity in 5 patients). Pulmonary fibrosis predated occurrence of MPA in 6 patients and was diagnosed concomitantly with MPA in 1 patient. During the follow-up, 10/17 patients died. The death was directly related to vasculitis in 3 patients. We conclude that patients with pulmonary fibrosis should be evaluated for the presence of ANCA. Patients with positive ANCA testing, particularly if anti-myeloperoxidase, should be carefully monitored to detect the occurrence of microscopic polyangiitis.

[Pulmonary imaging in ANCA-associated vasculitides]. / Imagerie pulmonaire dans les vascularites associées aux ANCA.

Imaging of ANCA-associated vasculitides principally shows nonsystematized alveolar opacities, predominantly central, that suggest alveolar hemorrhage, as well as uni- or multifocal alveolar opacities of variable interpretation, and nodules, including cavitary nodules. Other signs, observed more rarely on imaging, are interstitial lung diseases, tracheobronchial involvement, and pulmonary hypertension. The principal pulmonary signs of Wegener's granulomatosis are nodules and masses, sometimes cavitary, and areas of airspace consolidation that may or may not suggest diffuse alveolar hemorrhage. Except when the latter is present, the lesions correspond to necrotizing granulomatosis or organized pneumonia. The most frequent pulmonary signs of Churg-Strauss syndrome on computed tomography are ground glass areas or parenchymal consolidation in dispersed bands or with a predominantly subpleural distribution that expresses eosinophilic interstitial and alveolar infiltration. Alveolar hemorrhage is the most common expression of microscopic polyangiitis.

Imaging in sarcoidosis.

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology that may involve virtually any organ. Pulmonary involvement predominates, but sarcoidosis can involve multiple organs, with or without concomitant lung involvement. Aberrations on chest radiographs are present in more than 90% of patients with sarcoidosis. Bilateral hilar lymphadenopathy, with or without lung parenchymal infiltrates, is typical but a wide range of chest radiographic patterns may be observed. This article discusses the characteristic chest radiographic features of sarcoidosis and the prognostic value of the radiographic staging classification as espoused by Scadding more than 4 decades ago. Thin-section high-resolution computed tomographic (HRCT) scans more clearly elucidate the intrathoracic lesions observed in sarcoidosis and may discriminate active inflammation from end-stage fibrosis. Although HRCT is not necessary to manage all cases of sarcoidosis, HRCT may be invaluable in SELECTED patients with stage II or III sarcoidosis to discriminate alveolitis (which may be amenable to therapy) from fibrosis. Additionally, radionuclide techniques may have a role in extrapulmonary sarcoidosis (particularly when central nervous system or cardiac involvement is suspected). We review the salient features and role of magnetic resonance imaging and diverse radionuclide techniques to diagnose or follow selected cases of extrapulmonary sarcoidosis.

[Interstitial lung disease in systemic sclerosis]. / Pneumopathie infiltrante diffuse de la sclérodermie systémique.

Interstitial lung diseases (ILD) associated with systemic sclerosis (SSc) are mainly encountered in patients with diffuse disease, although they may also be seen in patients with limited cutaneous SSc. ILD screening must be performed regularly, with high-resolution computed tomography and pulmonary function tests (TLCO). Up to 75% of patients with diffuse SSc develop a form of ILD. ILD remains stable in most patients and does not worsen. The nonspecific nature of SSc-associated ILD makes it different from idiopathic ILD and helps to explain its better prognosis. Nonetheless, ILD is one of the two leading causes of death in SSc patients. Treatment of SSc-associated ILD is not yet well codified. Antifibrotic treatments have not proved beneficial, and the efficacy of cyclophosphamide, which has been used to treat this condition for 15 years, has been shown to be very limited against SSc-associated ILD. A subgroup of patients with rapidly progressive ILD might benefit from intravenous cyclophosphamide pulses in association with 15 mg/d prednisone.

[Churg-Strauss syndrome and pulmonary fibrosis: an unusual association]. / Syndrome de Churg-Strauss et fibrose pulmonaire: une association exceptionnelle.

INTRODUCTION: Churg-Strauss syndrome (CSS) is characterized by asthma, hypereosinophilia, and vasculitis involving at least two extrapulmonary organs. CASE: We report a case of a patient with antineutrophilic cytoplasmic antibody-negative CSS who developed pulmonary interstitial fibrosis (PIF). DISCUSSION: The possible relations between CSS and PIF are discussed. Because this case report is the first to describe features of pulmonary fibrosis in a patient with CSS, we cannot know whether this association is causal or fortuitous.

Increased uptake of 111In-octreotide in idiopathic pulmonary fibrosis.

UNLABELLED: Idiopathic pulmonary fibrosis (IPF) is characterized by an uncontrolled accumulation and activation of lung fibroblasts. A modulation of fibroblast activation has been observed in various systems with octreotide, a synthetic somatostatin analog with strong affinity for the somatostatin receptor subtype 2 (sst2). One aim of our study was to evaluate the expression of somatostatin receptors in the lungs of patients with IPF. A second aim was to evaluate the relationship between 111In-octreotide uptake and the effect of pulmonary fibrosis as assessed by lung function tests and parameters and by radiologic findings. METHODS: We investigated 11 patients with IPF, 6 patients with pulmonary fibrosis associated with systemic sclerosis (SSc), and 19 patients with disease not of the lung (control patients). The expression of somatostatin receptors was evaluated in vivo using 111In-octreotide scintigraphy. We evaluated the relationship between 111In-octreotide uptake and the activity of pulmonary fibrosis as assessed by lung function tests, bronchoalveolar lavage (BAL) cellularity, and high-resolution CT (HRCT) of the chest. Planar images and thoracic SPECT (24 h) were performed after injection of 222 MBq of 111In-octreotide. Lung uptake was quantified using the lung-to-background ratio (L/B). In addition, the expression of sst2 was evaluated in vitro, in frozen lung-tissue samples using autoradiography, and in human cultures of lung fibroblasts using a ligand-binding assay. RESULTS: Compared with lung uptake in control patients (median L/B, 1.25; range, 1.14-1.49), lung uptake was increased in all 11 IPF patients (median L/B, 2.63; range, 1.59-3.13; P < 0.001) and in 4 of 6 SSc patients (median L/B, 1.68; range, 1.42-2.16). The L/B was lower in SSc patients than in IPF patients (P = 0.011). Increased uptake correlated with the alteration of lung function (carbon monoxide diffusing capacity [rho = -0.655; P = 0.038], diffusing capacity for carbon monoxide and alveolar volume ratio [rho = -0.627; P = 0.047], vital capacity [rho = -0.609; P = 0.054], and total lung capacity [rho = -0.598; P = 0.058]) and with the intensity of alveolitis (total BAL cellularity [rho = 0.756; P = 0.045], neutrophil counts [rho = 0.738; P = 0.05]), and HRCT fibrosis score (rho = 0.673; P = 0.007). Autoradiography suggested that vascular structures were a prominent binding site. Lung fibroblasts expressed somatostatin receptors in vitro as measured by binding assay. CONCLUSION: Our preliminary results identified an increased expression of sst2 in (mainly idiopathic) pulmonary fibrosis. Lung uptake correlates with the alteration of lung function and with the intensity of alveolitis.

Pulmonary cystic disorder related to light chain deposition disease.

Light chain deposition disease (LCDD) is a rare disorder that very uncommonly affects the lung. We report three cases of severe cystic pulmonary LCDD leading to lung transplantation. Such a presentation has never been previously reported. The three patients present with a progressive obstructive pulmonary pattern associated with numerous cysts diffusely distributed in both lungs. The disease was histologically characterized by non-amyloid amorphous deposits in the alveolar walls, the small airways and the vessels. It was associated with emphysematous-like changes and small airway dilation. Monotypic kappa light chain fixation was demonstrated on the abnormal deposits and along the basement membranes. Electron microscopy revealed coarsely granular electron-dense deposits in the same localizations. Mild extrapulmonary deposits were found in salivary glands in one patient. No immunoproliferative disorder was identified. We conclude that LCDD may primarily affect the lung, present as a pulmonary cystic disorder, and lead to severe respiratory insufficiency.

Endoluminal stenosis of proximal bronchi in sarcoidosis: bronchoscopy, function, and evolution.

AIM: Endoluminal stenosis of proximal bronchi (ESPB) is a potentially severe manifestation of sarcoidosis. Unusual clinical presentation and variable response to medical treatment require specific attention to diagnosis and follow-up. DESIGN: Of 2,500 patients with sarcoidosis seen at our institution, we retrospectively identified 18 patients with stage 1-3 sarcoidosis and ESPB. Clinical manifestations, endoscopic findings, pulmonary function tests, follow-up, and therapeutic response were assessed. RESULTS: Respiratory symptoms were present in 17 patients (94%): cough and dyspnea (89% each), wheezing (83%), and hemoptysis (11%). Generalized symptoms (67%) and extrapulmonary manifestations (72%) of sarcoidosis were frequent. Three bronchoscopic patterns were observed: single stenosis (n = 3), multiple stenoses (n = 12), or diffuse narrowing of the bronchial tree (n = 3). The two former groups accounted for 45 ESPBs located in the left upper lobe (44.5%), the right upper and middle lobes (15.5% each), and the left lower lobe (11%). ESPBs were due to mural thickening of bronchi (n = 16) or associated with extrinsic compression by lymphadenopathy (n = 2). Endobronchial biopsies uniformly confirmed the presence of granulomas. FEV(1)/FVC ratio was < 70% in 12 patients (66.7%), with a correlation between the decrease of FEV(1)/FVC ratio and the number of ESPBs (R(2) = 0.31; p = 0.02). Patients treated with oral corticosteroids (n = 12) or methotrexate (n = 1) within the first 3 months had a good prognosis, whereas patients in whom treatment was delayed by > 3 months (n = 4) or who did not receive any systemic treatment (n = 1) acquired fixed ESPB and persistent ventilatory defects. CONCLUSIONS: ESPB is a rare and serious complication of sarcoidosis. Its clinical hallmarks include multiple respiratory symptoms, multiorgan involvement, and generalized symptoms. Treatment has to be started early to avoid the development of fixed stenotic lesions and irreversible pulmonary function impairment.

CT findings in severe thoracic sarcoidosis.

Severe thoracic sarcoidosis includes manifestations with significant clinical and functional impairment and a risk of mortality. Severe thoracic sarcoidosis can take on various clinical presentations and is associated with increased morbidity. The purpose of this article was to describe the CT findings in severe thoracic sarcoidosis and to explain some of their mechanisms. Subacute respiratory insufficiency is a rare and early complication due to a high profusion of pulmonary lesions. Chronic respiratory insufficiency due to pulmonary fibrosis is a frequent and late complication. Three main CT patterns are identified: bronchial distortion, honeycombing and linear opacities. CT can be helpful in diagnosing some mechanisms of central airway obstruction such as bronchial distortion due to pulmonary fibrosis or an extrinsic bronchial compression by enlarged lymph nodes. An intrinsic narrowing of the bronchial wall by endobronchial granulomatous lesions may be suggested by CT when it shows evidence of bronchial mural thickening. Pulmonary hypertension usually occurs in patients with end-stage pulmonary disease and is related to fibrotic destruction of the distal capillary bed and to the resultant chronic hypoxemia. Several other mechanisms may contribute to the development of pulmonary hypertension including extrinsic compression of major pulmonary arteries by enlarged lymph nodes and secondary pulmonary veno-occlusive disease. Aspergilloma colonization of a cavity is the main cause of hemoptysis in sarcoidosis. Other rare causes are bronchiesctasis, necrotizing bronchial aspergillosis, semi-invasive pulmonary aspergillosis, erosion of a pulmonary artery due to a necrotic sarcoidosis lesion, necrosis of parenchymal sarcoidosis lesions and specific endobronchial macroscopic lesions.