Chest Computed Tomographic Image Screening for Cystic Lung Diseases in Patients with Spontaneous Pneumothorax Is Cost Effective

Familial pulmonary cysts: A clue to diagnose Birt-Hogg-Dubé syndrome: A case report and literature review

Birt-Hogg-Dubé syndrome (BHD) is an inherited autosomal dominant condition caused by germline mutations in the FLCN gene, mapped to chromosome 17p11.2. Typical manifestations include pulmonary cysts, spontaneous pneumothorax, fibrofolliculomas, and kidney neoplasms. This report details the case of a 56-year-old female non-smoker diagnosed with multiple pulmonary cysts, presenting with a history of recurrent spontaneous pneumothorax. A computed tomography (CT) scan of her daughter revealed similar pulmonary cysts, raising suspicion of BHD. Further abdominal enhanced CT revealed a left renal tumour and cutaneous fibrofolliculomas on her daughter's neck. Consequently, whole-exome sequencing confirmed an FLCN germline mutation in the patient and three relatives, establishing a diagnosis of BHD. This case highlights the importance of familial pulmonary cysts as a clue for diagnosing BHD, providing crucial insights into comparable clinical presentations.

Risk of pneumothorax in Birt-Hogg-Dubé syndrome during pregnancy and birth

Birt-Hogg-Dubé syndrome (BHDS) is a genetic disorder characterized by fibrofolliculomas, renal cell cancer and lung cysts. Patients are at risk to develop pneumothorax but the magnitude of this risk during pregnancy is unknown. Information was obtained from 46 women with BHDS that had at least one pregnancy (BHDS-with preg), 18 female BHDS relatives without pregnancies (BHDS-no preg) and 25 non-BHDS female relatives with at least one pregnancy (noBHDS-with preg). In total, 77 pneumothoraces occurred in the BHDS-with preg group (mean 1.7/patient) and 11 in the BHDS-no preg group. Comparison of patient years for the first two groups showed pneumothorax incidence rates of 0.054 and 0.016, respectively. The incidence rate difference was significant [0.038 (CI 0.02-0.057), value of p-value 0.0001]. This difference is not caused by an increased number of patients with pneumothorax but by an increased number of pneumothoraces per patient. Pregnancy in BHDS therefore might be a risk factor for multiple pneumothoraces.

SPLF/SMFU/SRLF/SFAR/SFCTCV Guidelines for the management of patients with primary spontaneous pneumothorax

INTRODUCTION

Primary spontaneous pneumothorax (PSP) is the presence of air in the pleural space, occurring in the absence of trauma and known lung disease. Standardized expert guidelines on PSP are needed due to the variety of diagnostic methods, therapeutic strategies and medical and surgical disciplines involved in its management.

METHODS

Literature review, analysis of the literature according to the GRADE (Grading of Recommendation, Assessment, Development and Evaluation) methodology; proposals for guidelines rated by experts, patients and organizers to reach a consensus. Only expert opinions with strong agreement were selected.

RESULTS

A large PSP is defined as presence of a visible rim along the entire axillary line between the lung margin and the chest wall and ≥ 2 cm at the hilum level on frontal chest X-ray. The therapeutic strategy depends on the clinical presentation: emergency needle aspiration for tension PSP; in the absence of signs of severity: conservative management (small PSP), needle aspiration or chest tube drainage (large PSP). Outpatient treatment is possible if a dedicated outpatient care system is previously organized. Indications, surgical procedures and perioperative analgesia are detailed. Associated measures, including smoking cessation, are described.

CONCLUSION

These guidelines are a step towards PSP treatment and follow-up strategy optimization in France.

Probability of sporadic lymphangioleiomyomatosis in women presenting with spontaneous pneumothorax

BACKGROUND

Sporadic lymphangioleiomyomatosis (S-LAM) is a rare low-grade neoplasm of young women characterized by multiple pulmonary cysts leading to progressive dyspnea and recurrent spontaneous pneumothorax (SP). The diagnosis of S-LAM may be delayed by several years. To reduce this delay, chest computed tomography (CT) screening has been proposed to uncover cystic lung disease in women presenting with SP. However, the probability to discover S-LAM in this population has not been determined precisely. The aim of this study was to calculate the probability of finding S-LAM in women presenting with (a) SP, and (b) apparent primary SP (PSP) as first manifestation of S-LAM.

METHODS

Calculations were made by applying the Bayes theorem to published epidemiological data on S-LAM, SP and PSP. Each term of the Bayes equation was determined by meta-analysis, and included: (1) the prevalence of S-LAM in the general female population, (2) the incidence rate of SP and PSP in the general female population, and (3) the incidence rate of SP and apparent PSP in women with S-LAM.

RESULTS

The prevalence of S-LAM in the general female population was 3.03 per million (95% confidence interval 2.48, 3.62). The incidence rate of SP in the general female population was 9.54 (8.15, 11.17) per 100,000 person-years (p-y). The incidence rate of SP in women with S-LAM was 0.13 (0.08, 0.20). By combining these data in the Bayes theorem, the probability of finding S-LAM in women presenting with SP was 0.0036 (0.0025, 0.0051). For PSP, the incidence rate in the general female population was 2.70 (1.95, 3.74) per 100,000 p-y. The incidence rate of apparent PSP in women with S-LAM was 0.041 (0.030, 0.055). With the Bayes theorem, the probability of finding S-LAM in women presenting with apparent PSP as first disease manifestation was 0.0030 (0.0020, 0.0046). The number of CT scans to perform in women to find one case of S-LAM was 279 for SP and 331 for PSP.

CONCLUSION

The probability of discovering S-LAM at chest CT in women presenting with apparent PSP as first disease manifestation was low (0.3%). Recommending chest CT screening in this population should be reconsidered.

SPLF/SMFU/SRLF/SFAR/SFCTCV Guidelines for the management of patients with primary spontaneous pneumothorax: Endorsed by the French Speaking Society of Respiratory Diseases (SPLF), the French Society of Emergency Medicine (SFMU), the French Intensive Care Society (SRLF), the French Society of Anesthesia & Intensive Care Medicine (SFAR) and the French Society of Thoracic and Cardiovascular Surgery (SFCTCV)

INTRODUCTION

Primary spontaneous pneumothorax (PSP) is the presence of air in the pleural space, occurring in the absence of trauma and known lung disease. Standardized expert guidelines on PSP are needed due to the variety of diagnostic methods, therapeutic strategies and medical and surgical disciplines involved in its management.

METHODS

Literature review, analysis of literature according to the GRADE (Grading of Recommendation Assessment, Development and Evaluation) methodology; proposals for guidelines rated by experts, patients, and organizers to reach a consensus. Only expert opinions with strong agreement were selected.

RESULTS

A large PSP is defined as presence of a visible rim along the entire axillary line between the lung margin and the chest wall and ≥2 cm at the hilum level on frontal chest x-ray. The therapeutic strategy depends on the clinical presentation: emergency needle aspiration for tension PSP; in the absence of signs of severity: conservative management (small PSP), needle aspiration or chest tube drainage (large PSP). Outpatient treatment is possible if a dedicated outpatient care system is previously organized. Indications, surgical procedures and perioperative analgesia are detailed. Associated measures, including smoking cessation, are described.

CONCLUSION

These guidelines are a step towards PSP treatment and follow-up strategy optimization in France.

Recommandations formalisées d’experts pour la prise en charge des pneumothorax spontanés primaires

Introduction : Le pneumothorax spontané primaire (PSP) est un épanchement gazeux dans la cavité pleurale, survenant hors traumatisme et pathologie respiratoire connue. Des recommandations formalisées d'experts sur le sujet sont justifiées par les pluralités de moyens diagnostiques, stratégies thérapeutiques et disciplines médicochirurgicales intervenant dans leur prise en charge.

Méthodes : Revue bibliographique, analyse de la littérature selon méthodologie GRADE (Grading of Recommendation Assessment, Development and Evaluation) ; propositions de recommandations cotées par experts, patients et organisateurs pour obtenir un consensus. Seuls les avis d'experts avec accord fort ont été retenus.

Résultats : Un décollement sur toute la hauteur de la ligne axillaire et supérieur ou égal à 2 cm au niveau du hile à la radiographie thoracique de face définit la grande abondance. La stratégie thérapeutique dépend de la présentation clinique : exsufflation en urgence pour PSP suffocant ; en l'absence de signe de gravité : prise en charge conservatrice (faible abondance), exsufflation ou drainage (grande abondance). Le traitement ambulatoire est possible si organisation en amont de la filière. Les indications, procédures chirurgicales et l'analgésie périopératoire sont détaillées. Les mesures associées, notamment le sevrage tabagique, sont décrites.

Conclusion : Ces recommandations sont une étape de l'optimisation des stratégies de traitement et de suivi des PSP en France.

Lung transplantation for lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare cystic lung disease, associated with respiratory symptoms of dyspnea and spontaneous pneumothorax, along with various extra-thoracic manifestations. Often a progressive disease, albeit slowly, patients can develop chronic and severe respiratory failure and require supplemental oxygen. Lung transplantation (LTX) can offer improved duration and quality of life for patients with end-stage lung disease due to LAM. There are several unique considerations for LTX in LAM patients, and disease-specific complications of LAM prior to LTX can affect management decisions. Furthermore, there are several possible post-transplant issues specific to LAM. In this review, we discuss evaluation and management, disease-specific complications (both pre- and post-transplant), and outcomes for LAM patients undergoing lung transplantation.

Cystic lung disease

The term cystic lung disease encompasses a heterogeneous group of entities characterised by round lung lesions that correspond to cysts with fine walls, which usually contain air. The differential diagnosis of these lesions can be challenging, requiring both clinical and radiological perspectives. Entities such as pulmonary emphysema and cystic bronchiectasis can simulate cystic disease. High-resolution computed tomography (HRCT) is the imaging technique of choice for the evaluation and diagnosis of cystic lung disease, because it confirms the presence of lung disease and establishes the correct diagnosis of the associated complications. In many cases, the diagnosis can be established based on the HRCT findings, thus making histologic confirmation unnecessary. For these reasons, radiologists need to be familiar with the different presentations of these entities. A wide variety of diseases are characterised by the presence of diffuse pulmonary cysts. Among these, the most common are lymphangioleiomyomatosis, which may or may not be associated with tuberous sclerosis, Langerhans cell histiocytosis, and lymphocytic interstitial pneumonia. Other, less common entities include Birt-Hogg-Dubé syndrome, amyloidosis, and light-chain deposit disease. This article describes the characteristics and presentations of some of these entities, emphasizing the details that can help differentiate among them.

High-Resolution Computed Tomography of Cystic Lung Disease

The cystic lung diseases (CLD) are characterized by the presence of multiple, thin-walled, air-filled spaces in the pulmonary parenchyma. Cyst formation may occur with congenital, autoimmune, inflammatory, infectious, or neoplastic processes. Recognition of cyst mimics such as emphysema and bronchiectasis is important to prevent diagnostic confusion and unnecessary evaluation. Chest CT can be diagnostic or may guide the workup based on cyst number, distribution, morphology, and associated lung, and extrapulmonary findings. Diffuse CLD (DCLDs) are often considered those presenting with 10 or more cysts. The more commonly encountered DCLDs include lymphangioleiomyomatosis, pulmonary Langerhans' cell histiocytosis, lymphoid interstitial pneumonia, Birt-Hogg-Dubé syndrome, and amyloidosis/light chain deposition disease.

Birt-Hogg-Dubé syndrome in apparent primary spontaneous pneumothorax patients; results and recommendations for clinical practice

Background

Birt-Hogg-Dubé syndrome (BHD) is an inherited disease caused by pathogenic variants in the FLCN gene. One of the characteristics is the increased risk for spontaneous pneumothorax, likely due to the presence of pulmonary cysts mainly distributed under the carina. Due to variable expression and lack of awareness, BHD is likely to be underdiagnosed. We aimed to examine the prevalence of BHD in patients presenting with an apparent primary spontaneous pneumothorax and to evaluate the contribution of chest CT in establishing the diagnosis.

Methods

Patients who presented with apparent primary spontaneous pneumothorax between 2004 and 2017 in a large Dutch teaching hospital were enrolled in this quantitative cross-sectional study. A questionnaire was sent to eligible patients. Patients who completed the questionnaire and consented to further participation were invited to visit the hospital for genetic testing and low dose, volumetric chest CT.

Results

Genetic testing was performed in 88 patients with apparent primary spontaneous pneumothorax. Three patients were found to have a pathogenic variant in the FLCN gene (3.4%). No variants of unknown significance were detected. Pulmonary cysts were detected in 14 out of 83 participants with an available chest CT, six had more than one cyst. All three patients with BHD had multiple pulmonary cysts.

Conclusions

Based on previous literature and the present study, we believe that performing a chest CT in every patient presenting with primary spontaneous pneumothorax is justified. Subsequent genetic testing of the FLCN gene should be considered when multiple pulmonary cysts are present.

Trial registration

The study was registered at clinicaltrials.gov with reference NCT02916992.

Summary at a glance

Three out of 88 patients with an apparent primary spontaneous pneumothorax were diagnosed with Birt-Hogg-Dubé syndrome in this study and all three had multiple pulmonary cysts. We believe that performing a chest CT in every patient with an apparent primary spontaneous pneumothorax is justified to identify underlying diseases.

Machine learning to distinguish lymphangioleiomyomatosis from other diffuse cystic lung diseases

Patients with lymphangioleiomyomatosis (LAM) frequently experience delays in diagnosis, owing partly to the delayed characterization of imaging findings. This project aimed to develop a machine learning model to distinguish LAM from other diffuse cystic lung diseases (DCLDs). Computed tomography scans from patients with confirmed DCLDs were acquired from registry datasets and a recurrent convolutional neural network was trained for their classification. The final model provided sensitivity and specificity of 85% and 92%, respectively, for LAM, similar to the historical metrics of 88% and 97%, respectively, by experts. The proof-of-concept work holds promise as a clinically useful tool to assist in recognizing LAM.

Utility of thoracic computed tomography to predict need for early surgery and recurrence after first episode of primary spontaneous pneumothorax

INTRODUCTION

CT imaging is not advocated by British Thoracic Society guidelines after first episode of primary spontaneous pneumothorax (PSP). There is emerging evidence that emphysema-like changes and CT-based dystrophy severity score (DSS) can predict need for early surgery and recurrence.

OBJECTIVES

We aimed to assess the role of DSS during first episodes of PSP in predicting the need for early surgery and recurrence.

METHODS

We conducted a retrospective analysis of consecutive PSP episodes (n=197) admitted to our institution from 1 January 2012 to 31 December 2017. DSS was calculated based on type, number and distribution of blebs and bullae. Patients were categorised as low-grade (0-3) or high-grade (4-6) DSS assessed by a thoracic radiologist.

RESULTS

Forty-five PSP patients had CT at first presentation. Eight patients had low-grade DSS; all were managed non-surgically and none had recurrence over 12 months. Thirty-seven patients had high-grade DSS. Of these, 25 (67.5%) were managed surgically, with three having contralateral recurrence over 12 months; 12 (32.5%) were managed non-surgically, and of these two patients had ipsilateral recurrence over 12 months.

CONCLUSION

DSS seems to predict the need for early surgery and recurrence and CT can be used to risk-stratify patients after a first episode of PSP.

Lymphangioleiomyomatosis: pathogenesis, clinical features, diagnosis, and management

Lymphangioleiomyomatosis (LAM) is a slowly progressive, low-grade, metastasising neoplasm of women, characterised by infiltration of the lung parenchyma with abnormal smooth muscle-like cells, resulting in cystic lung destruction. The invading cell in LAM arises from an unknown source and harbours mutations in tuberous sclerosis complex (TSC) genes that result in constitutive activation of the mechanistic target of rapamycin (mTOR) pathway, dysregulated cellular proliferation, and a programme of frustrated lymphangiogenesis, culminating in disordered lung remodelling and respiratory failure. Over the past two decades, all facets of LAM basic and clinical science have seen important advances, including improved understanding of molecular mechanisms, novel diagnostic and prognostic biomarkers, effective treatment strategies, and comprehensive clinical practice guidelines. Further research is needed to better understand the natural history of LAM; develop more powerful diagnostic, prognostic, and predictive biomarkers; optimise the use of inhibitors of mTOR complex 1 in the treatment of LAM; and explore novel approaches to the development of remission-inducing therapies.

An evidence-based review of primary spontaneous pneumothorax in the adolescent population

Primary spontaneous pneumothorax (PSP) is a relatively common problem in emergency medicine. The incidence of PSP peaks in adolescence and is most common in tall, thin males. Recent advances in the care of patients with PSP have called into question traditional approaches to management. This clinical review highlights the changing management strategies for PSP and concludes with a proposed evidence-based pathway to guide the care of adolescents with PSP.

Prevalence of Birt-Hogg-Dubé Syndrome Determined Through Epidemiological Data on Spontaneous Pneumothorax and Bayes Theorem

Background: Birt-Hogg-Dubé syndrome (BHD) is a rare inherited disorder characterized by cutaneous fibrofolliculomas, multiple pulmonary cysts, recurrent spontaneous pneumothorax (SP), and renal tumors. More than 40 years after its description, the prevalence of BHD in the general population remains unknown. This study aimed at determining the prevalence of BHD by applying the Bayes theorem of conditional probability to epidemiological data on SP. Methods: We performed a meta-analysis of published data on: (1) the probability of having BHD among patients with apparent primary SP (4 studies), (2) the incidence rate of primary SP in the general population (9 studies), and (3) the probability of experiencing a SP in BHD (16 studies). Results were corrected for SP relapses, stratified by gender and year of study publication (before and after 2000), and computed with the Bayes equation. Results: The probability of having BHD among patients with apparent primary SP was 0.09 (95% confidence interval: 0.07, 0.11) or 9%. It was 0.20 (0.14, 0.27) in women and 0.05 (0.04, 0.07) in men. The incidence rate of primary SP in the general population was 8.69 (6.58, 11.46) per 100,000 person-years (p-y). It was 3.44 (2.36, 4.99) per 100,000 p-y in women and 13.96 (10.72, 18.18) per 100,000 p-y in men, and was about 2 times higher in studies published after 2000 than in those published before 2000. The probability of experiencing at least one SP among patients with BHD was 0.43 (0.31, 0.54) or 43%, without gender difference. By combining these data in the Bayes equation, we found a prevalence of BHD in the general population of 1.86 (1.16, 3.00) per million, with values of 1.86 (1.02, 3.39) per million in men, and 1.88 (0.97, 3.63) per million in women. Conclusion: The prevalence of BHD in the general population is about 2 cases per million, without difference between genders.

New insights into spontaneous pneumothorax: A review

A spontaneous pneumothorax is a pneumothorax that does not arise from trauma or an iatrogenic cause. Although the traditional classification of either primary or secondary spontaneous pneumothorax based on the absence or presence of overt underlying lung disease is still widely used, it is now well recognised that primary spontaneous pneumothorax is associated with underlying pleuropulmonary disease. Current evidence indicates that computed tomography screening for underlying disease should be considered in patients who present with spontaneous pneumothorax. Recent evidence suggests that conservative management has similar recurrence rates, less complications and shorter hospital stay compared with invasive interventions, even in large primary spontaneous pneumothoraces of >50%. A more conservative approach which is based on clinical assessment rather than pneumothorax size can thus be followed during the acute management in selected stable patients. The purpose of this review is to revisit the aetiology of spontaneous pneumothorax, identify which patients should be investigated for secondary causes and to give an overview of the management strategies at initial presentation as well as secondary prevention.

Update on Pulmonary Langerhans Cell Histiocytosis

Pulmonary Langerhans cell (LC) histiocytosis (PLCH) has unknown cause and is a rare neoplastic disorder characterized by the infiltration of lungs and various organs by bone marrow-derived Langerhans cells with an accompanying strong inflammatory response. These cells carry somatic mutations of BRAF gene and/or NRAS, KRAS, and MAP2K1 genes, which cause activation of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathway. PLCH occurs predominantly in young smokers, without gender predominance. Lungs might be involved as an isolated organ or as part of a multiorgan disease. High-resolution computed chest tomography plays an outstanding role in PLCH diagnosis. The typical radiological picture of PLCH is the presence of small intralobular nodules, “tree in bud” opacities, cavitated nodules, and thin- and thick-walled cysts, frequently confluent. Histological examination of the lesion and demonstration of characteristic eosinophilic granulomas with the presence of LCs that display antigen CD1a or CD207 in immunohistochemistry are required for definite diagnosis. Smoking cessation is the most important recommendation for PLCH patients, but treatment of progressive PLCH and multisystem disease is based on chemotherapy. Recently, new targeted therapies have been implemented.

Management and outcomes of pneumothorax in adult patients with Langerhans cell Histiocytosis

BACKGROUND

Pneumothorax may recur during pulmonary Langerhans cell histiocytosis (PLCH) patients' follow-up and its management is not standardised. The factors associated with pneumothorax recurrence are unknown.

METHODS

In this retrospective study, PLCH patients who experienced a pneumothorax and were followed for at least 6 months after the first episode were eligible. The objectives were to describe the treatment of the initial episode and pneumothorax recurrences during follow-up. We also searched for factors associated with pneumothorax recurrence and evaluated the effect on lung function outcome. Time to recurrence was estimated by the Kaplan Meier method and the cumulative hazard of recurrence handling all recurrent events was estimated. Univariate Cox models and Andersen-Gill counting process were used for statistical analyses.

RESULTS

Fourty-three patients (median age 26.5 years [interquartile range (IQR), 22.9-35.4]; 26 men, 39 current smokers) were included and followed for median time of 49 months. Chest tube drainage was the main management of the initial pneumothorax, which resolved in 70% of cases. Pneumothorax recurred in 23 (53%) patients, and overall 96 pneumothoraces were observed during the study period. In the subgroup of patients who experienced pneumothorax recurrence, the median number of episodes per patient was 3 [IQR, 2-4]. All but one recurrence occurred within 2 years after the first episode. Thoracic surgery neither delayed the time of occurrence of the first ipsilateral recurrence nor reduced the overall number of recurrences during the study period, although the rate of recurrence was lower after thoracotomy than following video-assisted thoracic surgery (p = 0.03). At the time of the first pneumothorax, the presence of air trapping on lung function testing was associated with increased risk of recurrence (hazard ratio = 5.08; 95% confidence interval [1.18, 21.8]; p = 0.03). Pneumothorax recurrence did not predict subsequent lung function decline (p = 0.058).

CONCLUSIONS

Our results show that pneumothorax recurrences occur during an "active" phase of PLCH. In this observational study, the time of occurrence of the first ipsilateral recurrence and the overall number of pneumothorax recurrences were similar after conservative and thoracic surgical treatments. Further studies are needed to determine the best management to reduce the risk of pneumothorax recurrence in PLCH patients.

Spontaneous pneumothorax and air travel in Pulmonary Langerhans cell histiocytosis: A patient survey

BACKGROUND

The optimal approach for management of spontaneous pneumothoraces (SPs) and the safety of air travel in patients with pulmonary Langerhans cell histiocytosis (PLCH) are not well established.

METHODS

Patients with PLCH were recruited from the Rare Lung Diseases Clinic Network and the Histiocytosis Association, and surveyed about disease manifestations and safety of air travel.

RESULTS

A total of 94 patients completed the survey. Median age at diagnosis of PLCH was 40 years (range: 15-67 years). Average interval between symptom onset and diagnosis was 2.9 years (range: -4 to 31 years). Twenty-two patients (23%) had at least one SP, of which 14 (64%) had at least one additional SP that showed either an ipsilateral recurrence (10 patients; 45%) or a contralateral recurrence (8 patients; 36%). Mean age at the time of first SP was 29 years. SP was the presenting manifestation that led to the diagnosis of PLCH in 19% of patients, typically after the second episode. Surgical pleurodesis reduced the recurrence rate of SP by half in comparison with conservative management (29% vs. 65%, p = 0.025). Two patients experienced an episode of SP during air travel, consistent with an air travel-related pneumothorax rate of 2.4% per patient and 0.27% per flight.

CONCLUSIONS

SP is a common manifestation of PLCH, can be seen in approximately one-fourth of the patients, and has a high recurrence risk. Surgical pleurodesis leads to a substantial reduction in the SP recurrence risk. The risk of an air travel-related SP in patients with PLCH is about 2-3 per thousand flights. TRIAL REGISTRY CLINICALTRIALS.GOV: NCT03052101.

Clinical outcomes and survival following lung transplantation in patients with pulmonary Langerhans cell histiocytosis

BACKGROUND AND OBJECTIVE

Disease-specific outcomes following lung transplantation (LT) in patients with pulmonary Langerhans cell histiocytosis (PLCH) are not well established. We queried the Organ Procurement and Transplantation Network database to identify adult PLCH patients who had undergone LT in the United States.

METHODS

Overall survival data were analysed with Kaplan-Meier curves. Cox proportional hazard model was used to determine the effect of demographic, clinical and physiological variables on post-transplant survival.

RESULTS

A total of 87 patients with PLCH underwent LT in the United States between October 1987 and June 2017, accounting for 0.25% of the total LT during this period. The mean age at LT for PLCH patients was 49 years (range: 19-67 years), with a near equal gender distribution. Bilateral sequential LT was performed in 71 patients (82%). Pulmonary hypertension was present in 85% of patients, with a mean pulmonary artery pressure of 38.5 ± 14.1 mm Hg. The mean pre-transplant forced expiratory volume in 1 s (FEV₁ ) was 41 ± 21% predicted and the mean 6-min walk distance was 221 ± 111 m. Median post-LT survival for PLCH patients was comparable to patients with other lung diseases (5.1 vs 5.5 years, P = 0.76). The actuarial Kaplan-Meier post-LT survival for PLCH patients was 85%, 65%, 49% and 22% at 1, 3, 5 and 10 years, respectively. Female sex (hazard ratio (HR): 0.40, 95% CI: 0.22-0.72), pre-transplant serum bilirubin (HR: 1.66, 95% CI: 1.23-2.26) and serum creatinine (HR: 4.03, 95% CI: 1.01-14.76) were independently associated with post-LT mortality in our cohort.

CONCLUSION

Post-LT survival in patients with PLCH is similar to patients with other lung diseases and is significantly affected by patient gender.

The Genetics of Pneumothorax

A genetic influence on spontaneous pneumothoraces-those occurring without a traumatic or iatrogenic cause-is supported by several lines of evidence: 1) pneumothorax can cluster in families (i.e., familial spontaneous pneumothorax), 2) mutations in the FLCN gene have been found in both familial and sporadic cases, and 3) pneumothorax is a known complication of several genetic syndromes. Herein, we review known genetic contributions to both sporadic and familial pneumothorax. We summarize the pneumothorax-associated genetic syndromes, including Birt-Hogg-Dubé syndrome, Marfan syndrome, vascular (type IV) Ehlers-Danlos syndrome, alpha-1 antitrypsin deficiency, tuberous sclerosis complex/lymphangioleiomyomatosis, Loeys-Dietz syndrome, cystic fibrosis, homocystinuria, and cutis laxa, among others. At times, pneumothorax is their herald manifestation. These syndromes have serious potential extrapulmonary complications (e.g., malignant renal tumors in Birt-Hogg-Dubé syndrome), and surveillance and/or treatment is available for most disorders; thus, establishing a diagnosis is critical. To facilitate this, we provide an algorithm to guide the clinician in discerning which cases of spontaneous pneumothorax may have a genetic or familial contribution, which cases warrant genetic testing, and which cases should prompt an evaluation by a geneticist.

Role of Radiologists in the Diagnosis of Unsuspected Birt-Hogg-Dubé Syndrome in a Tertiary Clinical Practice

OBJECTIVE. Birt-Hogg-Dubé (BHD) syndrome is considered rare. Growing evidence indicates that it is underdiagnosed. The purpose of this study is to ascertain the impact of radiology reports that suggest the possibility of BHD syndrome on downstream management and a final diagnosis of BHD syndrome. MATERIALS AND METHODS. In this retrospective study, electronic medical records were searched to identify radiology reports suggesting the possibility of BHD syndrome in patients without a known or suspected diagnosis. Clinical and demographic information, the specialty of the ordering clinician, and imaging findings and confidence conveyed in the radiology report (with BHD syndrome listed as the most likely diagnosis versus one among several possibilities but not as the leading diagnosis) were recorded. The resultant downstream evaluations that were captured included referral for genetic evaluation and subsequent diagnosis of BHD. RESULTS. Between 2004 and 2016, radiologists suggested a diagnosis of BHD syndrome in 87 patients. Of these patients, 15% (13/87) underwent genetic evaluation, and 54% of those patients (7/13) had positive findings. Genetic evaluation was more likely for patients with a history of pneumothorax (p = 0.004) or involvement of the lungs and kidneys (p = 0.003). The urology department referred the highest percentage of patients (31% [4/13]) for genetic evaluation. CONCLUSION. Radiologists have a unique opportunity to suggest BHD syndrome, allowing appropriate genetic testing, screening, and counseling of patients and their families. Clinical presentation, including a history of pneumothorax and involvement of both the lungs and kidneys on imaging, may determine which patients are ultimately referred for genetic evaluation. We hope that increasing awareness that BHD syndrome is not so rare may lead to early diagnosis.

Pneumothorax in Patients with Pulmonary Langerhans Cell Histiocytosis

Introduction

Pneumothorax often develops in pulmonary Langerhans cell histiocytosis (PLCH), but some patients take a long time to be correctly diagnosed.

Objectives

This study assessed the frequency of pneumothorax in PLCH and analysed the role of chest computed tomography (CT) in the prompt diagnosis.

Patients and material

Of the 90 patients with PLCH seen from 2000 to 2015, 29 (32%) had pneumothorax as the initial finding. In this group, 18 (62%) patients were diagnosed within 1 month, whereas the diagnosis was delayed for 4–120 months in 11 (38%) patients.

Results

Patients who had pneumothorax as the initial sign of PLCH tended to be younger (mean age 27.7 ± 7.92 vs. 39.9 ± 13.21 years; P = 0.0001), male (69% vs. 43%; P = 0.028), smoked less (mean pack/years 8.4 ± 6.85 vs. 19 ± 17.16; P = 0.003), and had a significantly lower mean FVC (77.96 ± 19.62 vs. 89.47 ± 21.86% pred.; P = 0.015) and FEV₁ (68.6 ± 19.93 vs. 79.4 ± 21.48% pred.; P = 0.03 than patients who had no pneumothorax. Recurrent pneumothorax was diagnosed more frequently in the group with a delayed diagnosis (82% vs. 39%; P = 0.02). CT was performed in all of the patients who were diagnosed promptly, but in none of the patients with a delayed diagnosis.

Conclusions

Patients who had pneumothorax as the initial sign of PLCH were younger, more frequently men, and had greater respiratory impairment than those who had no pneumothorax. CT in patients with pneumothorax led to a correct diagnosis of this disease.

Pulmonary manifestations in tuberous sclerosis complex

Tuberous sclerosis complex has manifestations in many organ systems, including brain, heart, kidney, skin, and lung. The primary manifestations in the lung are lymphangioleiomyomatosis (LAM) and multifocal micronodular pneumocyte hyperplasia (MMPH). LAM affects almost exclusively women, and causes cystic lung destruction, pneumothorax, and chylous pleural effusions. LAM can lead to dyspnea, oxygen dependence, and respiratory failure, with more rapid disease progression during the premenopausal years. In contrast, MMPH affects men and women equally, causing small nodular pulmonary deposits of type II pneumocytes that rarely progress to symptomatic disease. Here, we review the clinical features and pathogenesis of LAM and MMPH.

Cost-Effectiveness Analysis in Radiology: A Systematic Review

PURPOSE

Cost-effectiveness analyses (CEAs) have become more prevalent in radiology. However, the lack of standard methodology may lead to conflicting conclusions on the cost-effectiveness of an imaging modality and hinder CEA-based policy recommendations. This study reviews recent CEAs to identify areas of methodological variation, explore their impact on interpretation, and discuss optimal strategies for performing CEAs in radiology.

METHODS

We performed a systematic review for cost-utility analyses in radiology from 2013 to 2017. Cost and quality-of-life methods were analyzed and compared using the Consolidated Health Economic Evaluation Reporting Standards checklist.

RESULTS

Eighty cost-utility studies met our inclusion criteria. A payer perspective was the most common (70%) and hospital perspective the least common (5%). Fourteen studies (17.5%) did not report perspective, and 12 (15%) reported a perspective inconsistent with their performed analysis. Cost inclusion varied greatly between studies; adverse effects of imaging (20.5%) and hospitalization (34.6%) were the least frequently included direct costs. Studies that measured their own utilities most commonly used the EuroQol-5D and Short Form-6D questionnaires; however, most studies (80%) cited utilities from previous literature. Seventy-two studies (90%) used willingness-to-pay thresholds, and 30 used cost-effectiveness acceptability curves (41.7%).

CONCLUSION

We observed statistically significant methodological variation indicating the need for a standardized, accurate means of performing and presenting CEAs within radiology. We make several recommendations to address key problems regarding study perspective, cost inclusion, and use of willingness-to-pay thresholds. Further work is required to ensure comparability and transparency between studies such that policymakers are properly informed when utilizing CEA results.

Assessing the value of screening tools: reviewing the challenges and opportunities of cost-effectiveness analysis

Background

Screening is an important part of preventive medicine. Ideally, screening tools identify patients early enough to provide treatment and avoid or reduce symptoms and other consequences, improving health outcomes of the population at a reasonable cost. Cost-effectiveness analyses combine the expected benefits and costs of interventions and can be used to assess the value of screening tools.

Objective

This review seeks to evaluate the latest cost-effectiveness analyses on screening tools to identify the current challenges encountered and potential methods to overcome them.

Methods

A systematic literature search of EMBASE and MEDLINE identified cost-effectiveness analyses of screening tools published in 2017. Data extracted included the population, disease, screening tools, comparators, perspective, time horizon, discounting, and outcomes. Challenges and methodological suggestions were narratively synthesized.

Results

Four key categories were identified: screening pathways, pre-symptomatic disease, treatment outcomes, and non-health benefits. Not all studies included treatment outcomes; 15 studies (22%) did not include treatment following diagnosis. Quality-adjusted life years were used by 35 (51.4%) as the main outcome. Studies that undertook a societal perspective did not report non-health benefits and costs consistently. Two important challenges identified were (i) estimating the sojourn time, i.e., the time between when a patient can be identified by screening tests and when they would have been identified due to symptoms, and (ii) estimating the treatment effect and progression rates of patients identified early.

Conclusions

To capture all important costs and outcomes of a screening tool, screening pathways should be modeled including patient treatment. Also, false positive and false negative patients are likely to have important costs and consequences and should be included in the analysis. As these patients are difficult to identify in regular data sources, common treatment patterns should be used to determine how these patients are likely to be treated. It is important that assumptions are clearly indicated and that the consequences of these assumptions are tested in sensitivity analyses, particularly the assumptions of independence of consecutive tests and the level of patient and provider compliance to guidelines and sojourn times. As data is rarely available regarding the progression of undiagnosed patients, extrapolation from diagnosed patients may be necessary.

Air Travel-Related Spontaneous Pneumothorax in Diffuse Cystic Lung Diseases

Purpose of review

Spontaneous pneumothorax (SP) is a common manifestation of patients with diffuse cystic lung diseases (DCLDs) such as lymphangieoleiomyomatosis (LAM), pulmonary Langerhans cell histiocytosis (PLCH) and Birt-Hogg-Dubé syndrome (BHD). Air travel may pose an additional risk for the development of SP. Here, we summarize the literature pertaining to air travel related SP in DCLDs in order to assist patients and clinicians in appropriate decision-making with regards to air travel.

Recent Findings

Several recent studies have estimated that the per-flight risk of SP in patients with DCLDs is approximately 1%, with disease-specific risk estimates of 1.1-2.6% in LAM, 0-0.63% in BHD, and 0.37% in PLCH.

Summary

In general, it should be safe for most patients with DCLDs to undertake air travel. Patients should be counseled to seek medical attention and not board the airplane in the presence of sudden/new onset chest pain and/or dyspnea prior to boarding the plane.

Spontaneous Pneumothoraces in Patients with Birt-Hogg-Dubé Syndrome

RATIONALE

Spontaneous pneumothorax is a common complication of Birt-Hogg-Dubé syndrome (BHD).

OBJECTIVES

The optimal approach to treatment and prevention of BHD-associated spontaneous pneumothorax, and to advising patients with BHD regarding risk of pneumothorax associated with air travel, is not well established.

METHODS

Patients with BHD were recruited from the Rare Lung Diseases Clinic Network and the BHD Foundation and surveyed about disease manifestations and air travel experiences.

RESULTS

A total of 104 patients completed the survey. The average age at diagnosis was 47 years, with an average delay from first symptoms of 13 years. Pulmonary cysts were the most frequent phenotypic manifestation of BHD, present in 85% of patients. Spontaneous pneumothorax was the presenting manifestation that led to the diagnosis of BHD in 65% of patients, typically after the second episode (mean, 2.4 episodes). Seventy-nine (76%) of 104 patients had at least one spontaneous pneumothorax during their lifetime, and 82% had multiple pneumothoraces. Among patients with multiple pneumothoraces, 73% had an ipsilateral recurrence, and 48% had a subsequent contralateral spontaneous pneumothorax following a sentinel event. The mean ages at first and second pneumothoraces were 36.5 years (range, 14-63 yr) and 37 years (range, 20-55 yr), respectively. The average number of spontaneous pneumothoraces experienced by patients with a sentinel pneumothorax was 3.6. Pleurodesis was generally performed after the second (mean, 2.4) ipsilateral pneumothorax and reduced the ipsilateral recurrence rate by half. A total of 11 episodes of spontaneous pneumothorax occurred among eight patients either during or within the 24-hour period following air travel, consistent with an air travel-related pneumothorax rate of 8% per patient and 0.12% per flight. Prior pleurodesis reduced the occurrence of a subsequent flight-related pneumothorax.

CONCLUSIONS

Spontaneous pneumothorax is an important, recurrent manifestation of pulmonary involvement in patients with BHD, and pleurodesis should be considered following the initial pneumothorax to reduce the risk of recurrent episodes. In general, in patients with BHD, pneumothorax occurs in about 1-2 per 1,000 flights, and the risk is lower among patients with a history of prior pleurodesis.

Birt-Hogg-Dubé Syndrome: A Review of Dermatological Manifestations and Other Symptoms

Birt-Hogg-Dubé syndrome (BHD) is an autosomal dominant genodermatosis with malignant potential characterized by cutaneous and extracutaneous stigmata. Aberrations in the folliculin (FLCN) gene, which is located on chromosome 17, have been discovered in individuals with this condition. Over 150 unique mutations have been identified in BHD. The skin lesions associated with this condition include fibrofolliculomas, trichodiscomas, perifollicular fibromas, and acrochordons. Extracutaneous features of the syndrome typically include the lung (spontaneous pneumothorax and cysts) and the kidney (neoplasms). The only malignancies associated with BHD are renal cancers; however, other tumors have been observed in individuals with BHD. In this article, the skin lesions associated with this condition are reviewed, lung and renal manifestations associated with this syndrome are presented, and malignancies occurring in these patients are summarized.

Spontaneous pneumothorax in diffuse cystic lung diseases

PURPOSE OF REVIEW

Diffuse cystic lung diseases (DCLDs) are a heterogeneous group of disorders with varying pathophysiologic mechanisms that are characterized by the presence of air-filled lung cysts. These cysts are prone to rupture, leading to the development of recurrent spontaneous pneumothoraces. In this article, we review the epidemiology, clinical features, and management DCLD-associated spontaneous pneumothorax, with a focus on lymphangioleiomyomatosis, Birt-Hogg-Dubé syndrome, and pulmonary Langerhans cell histiocytosis.

RECENT FINDINGS

DCLDs are responsible for approximately 10% of apparent primary spontaneous pneumothoraces. Computed tomography screening for DCLDs (Birt-Hogg-Dubé syndrome, lymphangioleiomyomatosis, and pulmonary Langerhans cell histiocytosis) following the first spontaneous pneumothorax has recently been shown to be cost-effective and can help facilitate early diagnosis of the underlying disorders. Patients with DCLD-associated spontaneous pneumothorax have a very high rate of recurrence, and thus pleurodesis should be considered following the first episode of spontaneous pneumothorax in these patients, rather than waiting for a recurrent episode. Prior pleurodesis is not a contraindication to future lung transplant.

SUMMARY

Although DCLDs are uncommon, spontaneous pneumothorax is often the sentinel event that provides an opportunity for diagnosis. By understanding the burden and implications of pneumothoraces in DCLDs, clinicians can facilitate early diagnosis and appropriate management of the underlying disorders.

A 26-year-old man with dyspnea and chest pain

A 26-year-old smoker male presented with a history of sudden onset dyspnea and right-sided chest pain. Chest radiograph revealed large right-sided pneumothorax which was managed with tube thoracostomy. High-resolution computed tomography thorax revealed multiple lung cysts, and for a definite diagnosis, a video-assisted thoracoscopic surgery-guided lung biopsy was performed followed by pleurodesis. This clinicopathologic conference discusses the clinical and radiological differential diagnoses, utility of lung biopsy, and management options for patients with such a clinical presentation.