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.

How to Tackle the Diagnosis and Treatment in the Diverse Scenarios of Extrapulmonary Sarcoidosis.

Extrapulmonary sarcoidosis occurs in 30-50% of cases of sarcoidosis, most often in association with pulmonary involvement, and virtually any organ can be involved. Its incidence depends according to the organs considered, clinical phenotype, and history of sarcoidosis, but also on epidemiological factors like age, sex, geographic ancestry, and socio-professional factors. The presentation, symptomatology, organ dysfunction, severity, and lethal risk vary from and to patient even at the level of the same organ. The presentation may be specific or not, and its occurrence is at variable times in the history of sarcoidosis from initial to delayed. There are schematically two types of presentation, one when pulmonary sarcoidosis is first discovered, the problem is then to detect extrapulmonary localizations and to assess their link with sarcoidosis, while the other presentation is when extrapulmonary manifestations are indicative of the disease with the need to promptly make the diagnosis of sarcoidosis. To improve diagnosis accuracy, extrapulmonary manifestations need to be known and a medical strategy is warranted to avoid both under- and over-diagnosis. An accurate estimation of impairment and risk linked to extrapulmonary sarcoidosis is essential to offer the best treatment. Most frequent extrapulmonary localizations are skin lesions, arthritis, uveitis, peripheral lymphadenopathy, and hepatic involvement. Potentially severe involvement may stem from the heart, nervous system, kidney, eye and larynx. There is a lack of randomized trials to support recommendations which are often derived from what is known for lung sarcoidosis and from the natural history of the disease at the level of the respective organ. The treatment needs to be holistic and personalized, taking into account not only extrapulmonary localizations but also lung involvement, parasarcoidosis syndrome if any, symptoms, quality of life, medical history, drugs contra-indications, and potential adverse events and patient preferences. The treatment is based on the use of anti-sarcoidosis drugs, on treatments related to organ dysfunction and supportive treatments. Multidisciplinary discussions and referral to sarcoidosis centers of excellence may be helpful for difficult diagnosis and treatment decisions.

Intermittent Hypoxia Increases the Severity of Bleomycin-Induced Lung Injury in Mice.

BACKGROUND: Severe obstructive sleep apnea (OSA) with chronic intermittent hypoxia (IH) is common in idiopathic pulmonary fibrosis (IPF). Here, we evaluated the impact of IH on bleomycin- (BLM-) induced pulmonary fibrosis in mice. METHODS: C57BL/6J mice received intratracheal BLM or saline and were exposed to IH (40 cycles/hour; FiO2 nadir: 6%; 8 hours/day) or intermittent air (IA). In the four experimental groups, we evaluated (i) survival; (ii) alveolar inflammation, pulmonary edema, lung oxidative stress, and antioxidant enzymes; (iii) lung cell apoptosis; and (iv) pulmonary fibrosis. RESULTS: Survival at day 21 was lower in the BLM-IH group (p < 0.05). Pulmonary fibrosis was more severe at day 21 in BLM-IH mice, as assessed by lung collagen content (p = 0.02) and histology. At day 4, BLM-IH mice developed a more severe neutrophilic alveolitis, (p < 0.001). Lung oxidative stress was observed, and superoxide dismutase and glutathione peroxidase expression was decreased in BLM-IH mice (p < 0.05 versus BLM-IA group). At day 8, pulmonary edema was observed and lung cell apoptosis was increased in the BLM-IH group. CONCLUSION: These results show that exposure to chronic IH increases mortality, lung inflammation, and lung fibrosis in BLM-treated mice. This study raises the question of the worsening impact of severe OSA in IPF patients.

Effect of pulmonary arteriovenous malformations on the mechanical properties of the lungs.

BACKGROUND: Pulmonary arteriovenous malformations (PAVMs) are present in approximately 15-50% individuals with hereditary hemorrhagic telangiectasia (HHT). They may be isolated but more often are multiple. The goal of this study was to evaluate the influence of PAVMs on lung mechanical properties. METHODS: We reviewed the files of all adult patients (age ≥ 18 years) referred to our Center for evaluation of HHT between 2005 and 2013. The diagnosis of HHT was based on the Curacao criteria and/or the presence of a pathogenic mutation. Exclusion criteria included: chronic cardiac or lung disease (i.e. asthma or COPD), suspicion of pulmonary hypertension on echocardiography, current or past smoking (>10 pack-years), history of thoracic surgery, previous treatment of PAVMs by embolotherapy, lung infection or thromboembolic disease in the past 3 months, pregnancy and obesity (BMI > 30 kg/m2). Chest high resolution CT-scan and pulmonary function tests were performed the same day in all patients as part of our routine work-up. RESULTS: One hundred and fifty five patients with HHT were included (age: 44.4 ± 16.7 yrs - mean ± SD -; males: 39%). Eighty eight patients had no PAVM, 45 had 1-3 PAVMS and 22 had at least 4 PAVMs. Thirty eight patients had unilateral PAVMs and 29 bilateral PAVMs. We found no statistical relationship between the number, the size and the laterality of PAVMs and results of lung flows and volumes. CONCLUSION: We found no evidence that PAVMs have a significant influence on lung mechanical properties as measured using routine pulmonary function tests in adult patients with HHT, even in case of numerous, macroscopic or bilateral malformations.