Official American Thoracic Society/Japanese Respiratory Society Clinical Practice Guidelines: Lymphangioleiomyomatosis Diagnosis and Management

Lung cancer and lymphangioleiomyomatosis: A common complication in an uncommon condition

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Lymphangioleiomyomatosis as a potent lung cancer risk factor: Insights from a Japanese large cohort study

BACKGROUND AND OBJECTIVE

Lymphangioleiomyomatosis (LAM) is a rare neoplastic disease associated with the functional tumour suppressor genes TSC1 and TSC2 and causes structural destruction in the lungs, which could potentially increase the risk of lung cancer. However, this relationship remains unclear because of the rarity of the disease.

METHODS

We investigated the relative risk of developing lung cancer among patients diagnosed with LAM between 2001 and 2022 at a single high-volume centre in Japan, using data from the Japanese Cancer Registry as the reference population. Next-generation sequencing (NGS) was performed in cases where tumour samples were available.

RESULTS

Among 642 patients diagnosed with LAM (sporadic LAM, n = 557; tuberous sclerosis complex-LAM, n = 80; unclassified, n = 5), 13 (2.2%) were diagnosed with lung cancer during a median follow-up period of 5.13 years. All patients were female, 61.5% were never smokers, and the median age at lung cancer diagnosis was 53 years. Eight patients developed lung cancer after LAM diagnosis. The estimated incidence of lung cancer was 301.4 cases per 100,000 person-years, and the standardized incidence ratio was 13.6 (95% confidence interval, 6.2-21.0; p = 0.0008). Actionable genetic alterations were identified in 38.5% of the patients (EGFR: 3, ALK: 1 and ERBB2: 1). No findings suggested loss of TSC gene function in the two patients analysed by NGS.

CONCLUSION

Our study revealed that patients diagnosed with LAM had a significantly increased risk of lung cancer. Further research is warranted to clarify the carcinogenesis of lung cancer in patients with LAM.

Preoperative risk-factors for secondary spontaneous pneumothorax surgery in Japan: a nationwide database study

PURPOSE

We aimed to identify preoperative risk factors for secondary spontaneous pneumothorax surgery.

METHODS

The National Clinical Database of Japan, with six annual datasets from 2014 to 2019, was used. All patients who underwent surgery for secondary spontaneous pneumothorax were included, excluding those < 15 years old and those with incomplete data. The effects of preoperative risk factors were analyzed for operative mortality (mortality during hospitalization or within 30 days, regardless of hospitalization status), 30-day mortality, and postoperative respiratory morbidities.

RESULTS

Of the 18,309 patients enrolled in the study, operative mortality, 30-day mortality, and postoperative respiratory morbidities were observed in 654 (3.6%), 343 (1.9%), and 2258 (12.3%) patients, respectively. Increasing age, male sex, body mass index < 18.5 or > 30, performance status > 2, emergent surgery, interstitial pneumonia, and diabetes in preoperative co-morbidity, tumors, and other diseases in underlying lung disease were significant risk factors for operative mortality. Those for 30-day mortality included autoimmune disease instead of male sex and diabetes, while those for postoperative respiratory morbidities included lymphangiomyomatosis instead of a body mass index > 30.

CONCLUSION

We identified many preoperative risk factors for operative mortality, 30-day mortality, and postoperative respiratory morbidities in secondary spontaneous pneumothorax surgery. These findings will assist in selecting appropriate surgical candidates.

Diffuse Cystic Lung Disease: A Clinical Guide to Recognition and Management

TOPIC IMPORTANCE

Diffuse cystic lung diseases (DCLDs) represent a group of pathophysiologically heterogeneous entities that share a common radiologic phenotype of multiple thin-walled pulmonary cysts. DCLDs differ from the typical fibroinflammatory interstitial lung diseases in their epidemiology, clinical presentation, molecular pathogenesis, and therapeutic approaches, making them worthy of a distinct classification. The importance of timely and accurate identification of DCLDs is heightened by the impact on patient management including recent discoveries of targeted therapeutic approaches for some disorders.

REVIEW FINDINGS

This article offers a practical framework for evaluating patients with DCLD, indicating the most appropriate and current diagnostic and management approaches. We focus on the DCLDs that are most likely to be encountered by practicing pulmonologists: lymphangioleiomyomatosis, pulmonary Langerhans cell histiocytosis, Birt-Hogg-Dubé syndrome, and lymphoid interstitial pneumonia. Chest CT scan is the most informative noninvasive diagnostic modality to identify DCLDs. Thereafter, instituting a structured approach to high-yield associated factors (eg, medical, social, and family history; renal and dermatologic findings) increases the likelihood of identifying DCLDs and achieving a diagnosis.

SUMMARY

Although the individual diseases that comprise the DCLD family are rare, taken together, DCLDs can be encountered more frequently in clinical practice than commonly perceived. An increased eagerness among general pulmonary physicians to recognize these entities, coupled with a practical and systematic clinical approach to examinations and investigations, is required to improve case findings, allow earlier intervention, and reduce morbidity and mortality.

Clinical Trial Validation of Automated Segmentation and Scoring of Pulmonary Cysts in Thoracic CT Scans

In cystic lung diseases such as lymphangioleiomyomatosis (LAM), a CT-based cyst score that measures the percentage of the lung volume occupied by cysts is a common index of the cyst burden in the lungs. Although the current semi-automatic measurement of the cyst score is well established, it is susceptible to human operator variabilities. We recently developed a fully automatic method incorporating adaptive features in place of manual adjustments. In this clinical study, the automatic method is validated against the standard method in several aspects. These include the agreement between the cyst scores of the two methods, the agreement of each method with independent tests of pulmonary function, and the temporal consistency of the measurements in the consecutive visits of the same patients. We found that the automatic method agreed with the standard method as well as the agreement between two trained operators running the same standard method; both methods obtained the same level of correlation with laboratory pulmonary function tests; the automated method had better temporal consistency than the standard method (p < 0.0001). The study indicates that the automatic method could replace the standard method and provide better consistency in assessing the extent of cystic changes in the lungs of patients.

Improved Diffusion-Weighted Hyperpolarized 129Xe Lung MRI with Patch-Based Higher-Order, Singular Value Decomposition Denoising

RATIONALE AND OBJECTIVES

Hyperpolarized xenon (129Xe) MRI is a noninvasive method to assess pulmonary structure and function. To measure lung microstructure, diffusion-weighted imaging-commonly the apparent diffusion coefficient (ADC)-can be employed to map changes in alveolar-airspace size resulting from normal aging and pulmonary disease. However, low signal-to-noise ratio (SNR) decreases ADC measurement certainty, and biases ADC to spuriously low values. Further, these challenges are most severe in regions of the lung where alveolar simplification or emphysematous remodeling generate abnormally high ADCs. Here, we apply Global Local Higher Order Singular Value Decomposition (GLHOSVD) denoising to enhance image SNR, thereby reducing uncertainty and bias in diffusion measurements.

MATERIALS AND METHODS

GLHOSVD denoising was employed in simulated images and gas phantoms with known diffusion coefficients to validate its effectiveness and optimize parameters for analysis of diffusion-weighted 129Xe MRI. GLHOSVD was applied to data from 120 subjects (34 control, 39 cystic fibrosis (CF), 27 lymphangioleiomyomatosis (LAM), and 20 asthma). Image SNR, ADC, and distributed diffusivity coefficient (DDC) were compared before and after denoising using Wilcoxon signed-rank analysis for all images.

RESULTS

Denoising significantly increased SNR in simulated, phantom, and in-vivo images, showing a greater than 2-fold increase (p < 0.001) across diffusion-weighted images. Although mean ADC and DDC remained unchanged (p > 0.05), ADC and DDC standard deviation decreased significantly in denoised images (p < 0.001).

CONCLUSION

When applied to diffusion-weighted 129Xe images, GLHOSVD improved image quality and allowed airspace size to be quantified in high-diffusion regions of the lungs that were previously inaccessible to measurement due to prohibitively low SNR, thus providing insights into disease pathology.

Safety and efficacy of COVID-19 vaccination in the Chinese population with pulmonary lymphangioleiomyomatosis: a single-center retrospective study

BACKGROUND

The safety and efficacy of vaccination against coronavirus disease 2019 (COVID-19) in patients with lymphangioleiomyomatosis (LAM) is still unclear. This study investigates COVID-19 vaccine hesitancy, vaccine safety and efficacy, and COVID-19 symptoms in LAM patients.

RESULTS

In total, 181 LAM patients and 143 healthy individuals responded to the questionnaire. The vaccination rate of LAM patients was 77.34%, and 15.7% of vaccinated LAM patients experienced adverse events. Vaccination decreased the risk of LAM patients developing anorexia [OR: 0.17, 95% CI: (0.07, 0.43)], myalgia [OR: 0.34, 95% CI: (0.13, 0.84)], and ageusia [OR: 0.34, 95% CI: (0.14, 0.84)]. In LAM patients, a use of mTOR inhibitors reduced the risk of developing symptoms during COVID-19, including fatigue [OR: 0.18, 95% CI: (0.03, 0.95)], anorexia [OR: 0.30, 95% CI: (0.09, 0.96)], and ageusia [OR: 0.20, 95% CI: (0.06, 0.67)].

CONCLUSIONS

Vaccination rates in the LAM population were lower than those in the general population, as 22.7% (41/181) of LAM patients had hesitations regarding the COVID-19 vaccine. However, the safety of COVID-19 vaccination in the LAM cohort was comparable to the healthy population, and COVID-19 vaccination decreased the incidence of COVID-19 symptoms in LAM patients. In addition, mTOR inhibitors seem not to determine a greater risk of complications in patients with LAM during COVID-19.

Effect of mTOR inhibitors on the mortality and safety of patients with lymphangioleiomyomatosis on the lung transplantation waitlist: A retrospective cohort study

BACKGROUND

Although lung transplantation (LTx) is the last resort for patients with end-stage lymphangioleiomyomatosis (LAM), the high waitlist mortality is a source of concern in Japan. Discontinuation of mechanistic target of rapamycin (mTOR) inhibitors prior to LTx is recommended due to the incidence of severe adverse events. Therefore, we hypothesized that mTOR inhibitors may affect the mortality of patients with LAM on the LTx waitlist.

METHODS

We retrospectively compared the characteristics of consecutive patients with LAM on the LTx waitlist who were and were not receiving mTOR inhibitors.

RESULTS

Twenty-nine consecutive patients with LAM who listed our center between January 2004 and December 2021 were selected from the database and enrolled in the present study. Seventeen patients (58.6%) were receiving a mTOR inhibitor, sirolimus (treatment group). During a median listing period of 1277 days, 12 patients (41.4%) were hospitalized, six patients (20.7%) died from disease before LTx, and 15 patients underwent LTx. Among the deceased patients, four patients (66.6%) had pneumothoraces. The waitlist mortality in the treatment group was significantly lower than that in the non-treatment group (p = 0.03). Among the six patients who discontinued sirolimus in the treatment group, four patients (66.6%) were hospitalized with respiratory complications after the discontinuation of sirolimus. No mTOR inhibitor-related complications arose in the treatment group undergoing LTx (n = 7), including those on a reduced sirolimus dose.

CONCLUSIONS

Administration of an mTOR inhibitor until LTx may decrease waitlist mortality. Due to life-threatening events after discontinuing sirolimus pre-LTx, a reduced dose until LTx is permissible.

Spontaneous Hydropneumothorax After Pleurodesis in a Patient With Pulmonary Lymphangioleiomyomatosis With Associated Endometrial Cancer

Lymphangioleiomyomatosis (LAM) is a rare cystic disease that occurs due to the abnormal proliferation of smooth muscle-like cells. It primarily affects the lungs but can also have extrapulmonary manifestations such as lymphangioleiomyoma and angiomyolipomas. It is more common in young women of childbearing age, with female sex hormones contributing to the disease course. LAM can develop either through sporadic mutations or through genetic inheritance of the tuberous sclerosis complex (TSC) genes. TSC, LAM, and endometrial cancer are associated with mTOR pathway activation, which can explain why these diseases can co-exist, although the co-existence of LAM and endometrial cancer in the same patient is very rare. Due to the cystic nature of LAM, pneumothorax most often occurs at least once during the course of the disease, and most times, it is the first manifestation observed in LAM. These patients are also at high risk for recurrent pneumothorax, and when that occurs, pleurodesis is indicated. Unfortunately, pleurodesis still does not preclude a pneumothorax from occurring. We present the case of a female patient with LAM and endometrial cancer who was found to have an incidental spontaneous hydropneumothorax after pleurodesis. Patients with LAM should be closely monitored for the possible development of other mTOR-associated diseases. Moreover, when performing pleurodesis for recurrent pneumothorax in very high-risk patients, the procedure with the lowest recurrence rate should be utilized.

A Study on the Psychological Profile and Coping With the Disease in Patients With Lymphangioleiomyomatosis

Introduction

Lymphangioleiomyomatosis (LAM) is a rare disease that affects women almost exclusively. We aimed to determine the psychological profile in patients with LAM, and their potential association with sociodemographic and clinical features, and to know their role in coping with the disease.

Material and methods

Cross-sectional and descriptive study in collaboration with the Spanish Association of LAM (AELAM). The variables measured were: socio-demographic, psychological (anxiety, depression, demoralization, spirituality, resilience, social support), clinical (treatment) and health-related quality of life.

Results

We studied 87 LAM patients, with a mean (SD) age of 47.7 (7.7) years, and time since diagnose was 10.1 (5.4) years. 75.9% of patients were receiving sirolimus or everolimus, and oxygen therapy was required in 34.5% of patients. Anxiety was found in 46% of patients, depression in 55%, while only 2% presented demoralization and 14% deficit in spirituality. Social support and resilience were adequate. The "non-severe" group (without oxygen therapy) presented worse results in anxiety. A structural equation model to explore association between variables, showed very adequate fit indices: χ2(14) = 29.743 (p = .074); CFI = .983; TLI = .967; SRMR = .058; RMSEA = .075[.000-.128]. The model identifies resilience, spirituality and social support as "protective factors" from anxiety, depression, and demoralization.

Conclusions

This study performed on a large series of women with LAM describes their psychological profile, in addition to showing how they cope with the disease. We have found that other psychological constructs, such as perceived social support and resilience, are protective factors. Early psychological evaluation and intervention is necessary to reduce comorbidities and prevent mental health problems in women with LAM.

Novel developments in the study of estrogen in the pathogenesis and therapeutic intervention of lymphangioleiomyomatosis

OBJECTIVE

This study aimed to enhance the understanding of the role of estrogen in lymphangioleiomyomatosis(LAM) and to conclude the impact of estrogen-altering events on the condition and recent advances in estrogen-based treatments for LAM.

RESULTS

LAM development is strongly linked to mutations in the tuberous sclerosis gene (TSC1/2) and the presence of estrogen. Estrogen plays a significant role in the spread of TSC2-deficient uterine leiomyoma cells to the lungs and the production of pulmonary LAM. Menstruation, pregnancy, estrogen medication, and other events that cause an increase in estrogen levels can trigger the disorder, leading to a sudden worsening of symptoms. Current findings do not support using estrogen-blocking therapy regimens. However, Faslodex, which is an estrogen receptor antagonist, presents new possibilities for future therapeutic approaches in LAM.

CONCLUSION

Estrogen is crucial in the development and spread of LAM. The use of estrogen inhibitors or estrogen receptor antagonists alone does not provide good control of the disease or even poses a greater risk, and the use of a combination of mTOR receptor inhibitors, complete estrogen receptor antagonists, estrogen inhibitors, and autophagy inhibitors targeting important signaling pathways in LAM pathogenesis may be of greater benefit to the patient.

Pulmonary function test results are correlated with 6-minute walk distance, distance-saturation product, and 6-minute walk work in patients with lymphangioleiomyomatosis

BACKGROUND AND OBJECTIVE

Lymphangioleiomyomatosis (LAM) is a rare multicystic lung disease. Although a correlation between pulmonary function test (PFT) results and exercise capacity appears probable, it has not yet been demonstrated. The aim of this study was to assess whether PFT results correlate with 6-minute walk test (6MWT) results in patients with LAM.

METHODS

We conducted a retrospective study of all patients with a diagnosis of LAM followed in a French reference centre over a 13-year period. PFT and 6MWT data were collected. Distance-saturation product (DSP) and 6-minute walk work (6MWORK) were calculated.

RESULTS

A total of 62 patients were included. Their median forced expiratory volume in 1 s (FEV1) was 82.7 % predicted and their median forced vital capacity (FVC) was 96.7 % predicted. The median diffusing capacity of the lungs for carbon monoxide (DLCO) was 58.5 % predicted and was decreased in 79 % of the patients. The median 6-minute walk distance was 535 m, which was 90.9 % of the 602 m predicted distance. The median DSP was 497.4 m % and the median 6MWORK was 32,910 kg.m. The distance walked during the 6MWT was significantly correlated with FVC%predicted (R = 0.435), FEV1 %predicted (R = 0.303), TLC%predicted (R = 0.345), FRC%predicted (R = 0.262), RV/TLC ratio (R = -0.271), and DLCO%predicted (R = 0.279). DSP and 6MWORK were each significantly correlated with different PFT results.

CONCLUSION

The present study shows that PFT results are potential predictors of the exercise capacity in patients with LAM. Additional studies are required to evaluate the interest of DSP and 6MWORK in LAM.

Glycoprotein non-metastatic melanoma protein B promotes tumor growth and is a biomarker for lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare, progressive cystic lung disease affecting almost exclusively female-sexed individuals. The cysts represent regions of lung destruction caused by smooth muscle tumors containing mutations in one of the two tuberous sclerosis (TSC) genes. mTORC1 inhibition slows but does not stop LAM advancement. Furthermore, monitoring disease progression is hindered by insufficient biomarkers. Therefore, new treatment options and biomarkers are needed. LAM cells express melanocytic markers, including glycoprotein non-metastatic melanoma protein B (GPNMB). The function of GPNMB in LAM is currently unknown; however, GPNMB's unique cell surface expression on tumor versus benign cells makes GPNMB a potential therapeutic target, and persistent release of its extracellular ectodomain suggests potential as a serum biomarker. Here, we establish that GPNMB expression is dependent on mTORC1 signaling, and that GPNMB regulates TSC2-null tumor cell invasion in vitro. Further, we demonstrate that GPNMB enhances TSC2-null xenograft tumor growth in vivo, and that ectodomain release is required for this xenograft growth. We also show that GPNMB's ectodomain is released from the cell surface of TSC2-null cells by proteases ADAM10 and 17, and we identify the protease target sequence on GPNMB. Finally, we demonstrate that GPNMB's ectodomain is present at higher levels in LAM patient serum compared to healthy controls and that ectodomain levels decrease with mTORC1 inhibition, making it a potential LAM biomarker.

Lymphangioleiomyomatosis and pregnancy: a mini-review

Lymphangioleiomyomatosis(LAM) is a slow progressive, rare cystic lung disease in women of reproductive age, associated with infiltration of the lung by atypical smooth muscle like cells, leading to the cystic destruction of the lung parenchyma. As LAM exclusively affects women of childbearing age, it can arise or exacerbate during pregnancy. Many patients with LAM are discouraged from pregnancy, although there is not much objective evidence effect on fertility. Patients diagnosed with LAM during pregnancy experience worse outcomes, so the safety of pregnancy is a vexing problem. What was worse, treatment strategies are limited on the effects of LAM on pregnancy outcomes. Pregnancy could be considered in LAM patients. Successful delivery in women with LAM depends on the condition of the LAM, which is in turn dependent on obstetricians and respiratory physicians. In this review, we describe the epidemiology, pathogenesis, diagnosis, clinical features and the treatment strategies of LAM during pregnancy.

Epidemiology of patients with lymphangioleiomyomatosis: A descriptive study using the national database of health insurance claims and specific health checkups of Japan

BACKGROUND

Using patient registries or limited regional hospitalization data may result in underestimation of the incidence and prevalence of rare diseases. Therefore, we used the national administrative database to estimate the incidence and prevalence of lymphangioleiomyomatosis over six years (2014-2019) and describe changes in clinical practice and mortality.

METHODS

We extracted data from the National Database of Health Insurance Claims and Specific Health Checkups of Japan between January 2013 and December 2020. This database covers ≥99% of the population. We used the diagnostic code for lymphangioleiomyomatosis to estimate the incidence and prevalence from 2014 to 2019. Additionally, we examined the demographic characteristics, treatments, comorbidities, and mortality of the patients.

RESULTS

In women, the incidence and prevalence of lymphangioleiomyomatosis in 2019 were approximately 3 per 1,000,000 person-years and 28.7 per 1,000,000 persons, respectively. While, in men, the incidence and prevalence of lymphangioleiomyomatosis were <0.2 per 1,000,000 person-years and 0.8 per 1,000,000 persons, respectively. From 2014 to 2019, the proportion of prescriptions of sirolimus and everolimus increased, while the use of home oxygen therapy, chest drainage, comorbid pneumothorax, and bloody phlegm decreased. The mortality rate remained stable at approximately 1%.

CONCLUSIONS

The incidence and prevalence of lymphangioleiomyomatosis were higher in women than those reported previously. Although the incidence did not change during the 6-year period, the prevalence gradually increased. Moreover, lymphangioleiomyomatosis was observed to be rare in men. The practice of treating patients with lymphangioleiomyomatosis changed across the six years while mortality remained low, at approximately 1%.

A 20-year-old woman with chronic cough and dyspnea

Lymphangioleiomyomatosis is a rare progressive disease characterized by abnormal smooth muscle cell proliferation leading to a diffuse cystic lung disease and extrapulmonary manifestations. Most cases are caused by mutations in the TSC1 and/or TSC2 genes, which are also associated with tuberous sclerosis complex. We describe a case of sporadic lymphangioleiomyomatosis with autosomal dominant polycystic kidney disease and renal angiolipomas in a patient who tested negative for gene mutations on the TSC1 and TSC2 gene panel.

A 24-year-Old woman with recurrent pneumothoraces

Lymphangioleiomyomatosis (LAM) is an abnormal proliferation of smooth muscle-like cells and may occur sporadically or in association with tuberous sclerosis complex. Patients are typically female, nonsmoking and may have cystic lung disease with pneumothorax. Diagnosis can be made by compatible imaging findings with a history of tuberous sclerosis complex, or in conjunction with vascular endothelial growth factor-D 800 pg/ml or greater, a highly specific finding. Sirolimus is first line treatment for LAM.

Diagnosis of cystic lung diseases: a position statement from the UK Cystic Lung Disease Rare Disease Collaborative Network

BACKGROUND

Rare cystic lung diseases are increasingly recognised due the wider application of CT scanning making cystic lung disease management a growing part of respiratory care. Cystic lung diseases tend to have extrapulmonary features that can both be diagnostic but also require surveillance and treatment in their own right. As some of these diseases now have specific treatments, making a precise diagnosis is crucial. While Langerhans cell histiocytosis, Birt-Hogg-Dubé syndrome, lymphoid interstitial pneumonia and lymphangioleiomyomatosis are becoming relatively well-known diseases to respiratory physicians, a targeted and thorough workup improves diagnostic accuracy and may suggest other ultrarare diseases such as light chain deposition disease, cystic pulmonary amyloidosis, low-grade metastatic neoplasms or infections. In many cases, diagnostic information is overlooked leaving uncertainty over the disease course and treatments.

AIMS

This position statement from the Rare Disease Collaborative Network for cystic lung diseases will review how clinical, radiological and physiological features can be used to differentiate between these diseases.

NARRATIVE

We highlight that in many cases a multidisciplinary diagnosis can be made without the need for lung biopsy and discuss where tissue sampling is necessary when non-invasive methods leave diagnostic doubt. We suggest an initial workup focusing on points in the history which identify key disease features, underlying systemic and familial diseases and a clinical examination to search for connective tissue disease and features of genetic causes of lung cysts. All patients should have a CT of the thorax and abdomen to characterise the pattern and burden of lung cysts and extrapulmonary features and also spirometry, gas transfer and a 6 min walk test. Discussion with a rare cystic lung disease centre is suggested before a surgical biopsy is undertaken.

CONCLUSIONS

We suggest that this focused workup should be performed in all people with multiple lung cysts and would streamline referral pathways, help guide early treatment, management decisions, improve patient experience and reduce overall care costs. It could also potentially catalyse a national research database to describe these less well-understood and unidentified diseases, categorise disease phenotypes and outcomes, potentially leading to better prognostic data and generating a stronger platform to understand specific disease biology.

The role of moesin in diagnosing and assessing severity of lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a rare disease which is easily misdiagnosed. Vascular endothelial growth factor D (VEGF-D), as the most common biomarker, however, is not so perfect for the diagnosis and severity assessment of LAM.

MATERIALS AND METHODS

The isobaric tags for relative and absolute quantitation (iTRAQ)-based method was used to identify a cytoskeleton protein, moesin. 84 patients with LAM, 44 patients with other cystic lung diseases (OCLDs), and 37 healthy control subjects were recruited for collecting blood samples and clinical data. The levels of moesin in serum were evaluated by ELISA. The relationships of moesin with lymphatic involvement, lung function, and treatment decision were explored in patients with LAM.

RESULTS

The candidate protein moesin was identified by the proteomics-based bioinformatic analysis. The serum levels of moesin were higher in patients with LAM [219.0 (118.7-260.5) pg/mL] than in patients with OCLDs (125.8 ± 59.9 pg/mL, P < 0.0001) and healthy women [49.6 (35.5-78.9) ng/mL, P < 0.0001]. Moesin had an area under the receiver operator characteristic curve (AUC) of 0.929 for predicting LAM diagnosis compared to healthy women (sensitivity 81.0%, specificity 94.6%). The combination of moesin and VEGF-D made a better prediction in differentiating LAM from OCLDs than moesin or VEGF-D alone. Moreover, elevated levels of moesin were related to lymphatic involvement in patients with LAM. Moesin was found negatively correlated with FEV1%pred, FEV1/FVC, and DLCO%pred (P = 0.0181, r = - 0.3398; P = 0.0067, r = - 0.3863; P = 0.0010, r = - 0.4744). A composite score combining moesin and VEGF-D improved prediction for sirolimus treatment, compared with each biomarker alone.

CONCLUSION

Higher levels of moesin in serum may indicate impaired lung function and lymphatic involvement in patients with LAM, suggest a more serious condition, and provide clinical guidance for sirolimus treatment.

[Genetic diffuse cystic lung disease in adults]

Multiple cystic lung diseases comprise a wide range of various diseases, some of them of genetic origin. Lymphangioleiomyomatosis (LAM) is a disease occurring almost exclusively in women, sporadically or in association with tuberous sclerosis complex (TSC). Patients with LAM present with lymphatic complications, renal angiomyolipomas and cystic lung disease responsible for spontaneous pneumothoraces and progressive respiratory insufficiency. TSC and LAM have been ascribed to mutations in TSC1 or TSC2 genes. Patients with TSC are variably affected by cutaneous, cognitive and neuropsychiatric manifestations, epilepsy, cerebral and renal tumors, usually of benign nature. Birt-Hogg-Dubé syndrome is caused by mutations in FLCN encoding folliculin. This syndrome includes lung cysts of basal predominance, cutaneous fibrofolliculomas and various renal tumors. The main complications are spontaneous pneumothoraces and renal tumors requiring systematic screening. The mammalian target of rapamycin (mTOR) pathway is involved in the pathophysiology of TSC, sporadic LAM and Birt-Hogg-Dubé syndrome. MTOR inhibitors are used in LAM and in TSC while Birt-Hogg-Dubé syndrome does not progress towards chronic respiratory failure. Future challenges in these often under-recognized diseases include the need to reduce the delay to diagnosis, and to develop potentially curative treatments. In France, physicians can seek help from the network of reference centers for the diagnosis and management of rare pulmonary diseases.

Hyperactive mTORC1 in lung mesenchyme induces endothelial cell dysfunction and pulmonary vascular remodeling

Lymphangioleiomyomatosis (LAM) is a progressive cystic lung disease caused by tuberous sclerosis complex 1/2 (TSC1/2) gene mutations in pulmonary mesenchymal cells, resulting in activation of the mechanistic target of rapamycin complex 1 (mTORC1). A subset of patients with LAM develop pulmonary vascular remodeling and pulmonary hypertension. Little, however, is known regarding how LAM cells communicate with endothelial cells (ECs) to trigger vascular remodeling. In end-stage LAM lung explants, we identified EC dysfunction characterized by increased EC proliferation and migration, defective angiogenesis, and dysmorphic endothelial tube network formation. To model LAM disease, we used an mTORC1 gain-of-function mouse model with a Tsc2 KO (Tsc2KO) specific to lung mesenchyme (Tbx4LME-Cre Tsc2fl/fl), similar to the mesenchyme-specific genetic alterations seen in human disease. As early as 8 weeks of age, ECs from mice exhibited marked transcriptomic changes despite an absence of morphological changes to the distal lung microvasculature. In contrast, 1-year-old Tbx4LME-Cre Tsc2fl/fl mice spontaneously developed pulmonary vascular remodeling with increased medial thickness. Single-cell RNA-Seq of 1-year-old mouse lung cells identified paracrine ligands originating from Tsc2KO mesenchyme, which can signal through receptors in arterial ECs. These ECs had transcriptionally altered genes including those in pathways associated with blood vessel remodeling. The proposed pathophysiologic mesenchymal ligand-EC receptor crosstalk highlights the importance of an altered mesenchymal cell/EC axis in LAM and other hyperactive mTORC1-driven diseases. Since ECs in patients with LAM and in Tbx4LME-Cre Tsc2fl/fl mice did not harbor TSC2 mutations, our study demonstrates that constitutively active mTORC1 lung mesenchymal cells orchestrated dysfunctional EC responses that contributed to pulmonary vascular remodeling.

Lymphangioleiomyomatosis with Tuberous Sclerosis Complex-A Case Study

Lymphangioleiomyomatosis (LAM) is characterized by lung cysts that cause lung deterioration, changes in the lymphatic system, and tumors in the kidneys. It mainly affects women of reproductive age and is a progressive disease. LAM can occur as an isolated disease or coexist with tuberous sclerosis (TSC). The source of LAM cells is unknown. Patients with confirmed LAM should be treated with an mTOR inhibitor, sirolimus, or everolimus. We present a case of LAM with TSC in a patient whose symptoms, including those in the lymph nodes and chyaloperitoneum, mainly concern the abdominal cavity.

Automated Segmentation and Measurements of Pulmonary Cysts in Lymphangioleiomyomatosis across Multiple CT Scanner Platforms over a Period of Two Decades

(1) Background: Lymphangioleiomyomatosis is a genetic disease that affects mostly women of childbearing age. In the lungs, it manifests as the progressive formation of air-filled cysts and is associated with a decline in lung function. With a median survival of 29 years after the onset of symptoms, computed-tomographic monitoring of cystic changes in the lungs is a key part of the management of the disease. However, the current standard method to measure cyst burdens from CT is semi-automatic and requires manual adjustments from trained operators to obtain consistent results due to variabilities in CT technology and imaging conditions over the long course of the disease. This can be impractical for longitudinal studies involving large numbers of scans and is susceptible to subjective biases. (2) Methods: We developed an automated method of pulmonary cyst segmentation for chest CT images incorporating novel graphics processing algorithms. We assessed its performance against the gold-standard semi-automated method performed by experienced operators who were blinded to the results of the automated method. (3) Results: the automated method had the same consistency over time as the gold-standard method, but its cyst scores were more strongly correlated with concurrent pulmonary function results from the physiology laboratory than those of the gold-standard method. (4) Conclusions: The automated cyst segmentation is a competent replacement for the gold-standard semi-automated process. It is a solution for saving time and labor in clinical studies of lymphangioleiomyomatosis that may involve large numbers of chest CT scans from diverse scanner platforms and protocols.

Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is an ultra-rare, slowly progressive neoplastic cystic disease, belonging to the group of PEComas. It can occur sporadically or associated to tuberous sclerosis complex disease and affects mainly women in child-birth age. Dyspnoea is the most frequent symptom referred to the time of diagnosis, however spontaneous pneumothorax may be a typical presentation associated to extrathoracic manifestations, such as renal angiomyolipomas. In the last decade, important advances in understanding molecular mechanisms underlying the LAM pathogenesis have been reached. It has allowed to obtain improvements in the research of novel biomarkers, treatment and a better management of the disease.

Back to the Future II-A Comprehensive Update on the Rapidly Evolving Field of Lymphatic Imaging and Interventions

ABSTRACT

Lymphatic imaging and interventional therapies of disorders affecting the lymphatic vascular system have evolved rapidly in recent years. Although x-ray lymphangiography had been all but replaced by the advent of cross-sectional imaging and the scientific focus shifted to lymph node imaging (eg, for detection of metastatic disease), interest in lymph vessel imaging was rekindled by the introduction of lymphatic interventional treatments in the late 1990s. Although x-ray lymphangiography is still the mainstay imaging technique to guide interventional procedures, several other, often less invasive, techniques have been developed more recently to evaluate the lymphatic vascular system and associated pathologies. Especially the introduction of magnetic resonance, and even more recently computed tomography, lymphangiography with water-soluble iodinated contrast agent has furthered our understanding of complex pathophysiological backgrounds of lymphatic diseases. This has led to an improvement of treatment approaches, especially of nontraumatic disorders caused by lymphatic flow abnormalities including plastic bronchitis, protein-losing enteropathy, and nontraumatic chylolymphatic leakages. The therapeutic armamentarium has also constantly grown and diversified in recent years with the introduction of more complex catheter-based and interstitial embolization techniques, lymph vessel stenting, lymphovenous anastomoses, as well as (targeted) medical treatment options. The aim of this article is to review the relevant spectrum of lymphatic disorders with currently available radiological imaging and interventional techniques, as well as the application of these methods in specific, individual clinical situations.

Unexpected sirolimus-stimulated airway hyperreactivity in lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a multisystem disease affecting primarily women, characterised in the lung by proliferation of LAM cells, abnormal smooth muscle-like cells with dysfunctional tuberous sclerosis complex genes. This dysfunction results in activation of mechanistic target of rapamycin (mTOR), leading to LAM cell proliferation. Sirolimus (rapamycin) is the only United States Food and Drug Administration-approved treatment for pulmonary LAM, resulting in decreased LAM cell growth/size and stabilised lung function [1].

Predicting Individualized Lung Disease Progression in Treatment-Naive Patients With Lymphangioleiomyomatosis

BACKGROUND

Lung function decline varies significantly in patients with lymphangioleiomyomatosis (LAM), impeding individualized clinical decision-making.

RESEARCH QUESTION

Can we aid individualized decision-making in LAM by developing a dynamic prediction model that can estimate the probability of clinically relevant FEV1 decline in patients with LAM before treatment initiation?

STUDY DESIGN AND METHODS

Patients observed in the US National Heart, Lung, and Blood Institute (NHLBI) Lymphangioleiomyomatosis Registry were included. Using routinely available variables such as age at diagnosis, menopausal status, and baseline lung function (FEV1 and diffusing capacity of the lungs for carbon monoxide [Dlco]), we used novel stochastic modeling and evaluated predictive probabilities for clinically relevant drops in FEV1. We formed predictive probabilities of transplant-free survival by jointly modeling longitudinal FEV1 and lung transplantation or death events. External validation used the UK Lymphangioleiomyomatosis Natural History cohort.

RESULTS

Analysis of the NHLBI Lymphangioleiomyomatosis Registry and UK Lymphangioleiomyomatosis Natural History cohorts consisted of 216 and 185 individuals, respectively. We derived a joint model that accurately estimated the risk of future lung function decline and 5-year probabilities of transplant-free survival in patients with LAM not taking sirolimus (area under the receiver operating characteristic curve [AUC], approximately 0.80). The prediction model provided estimates of forecasted FEV1, rate of FEV1 decline, and probabilities for risk of prolonged drops in FEV1 for untreated patients with LAM with a high degree of accuracy (AUC > 0.80) for the derivation cohort as well as the validation cohort. Our tool is freely accessible at: https://anushkapalipana.shinyapps.io/testapp_v2/.

INTERPRETATION

Longitudinal modeling of routine clinical data can allow individualized LAM prognostication and assist in decision-making regarding the timing of treatment initiation.

French recommendations for the diagnosis and management of lymphangioleiomyomatosis

BACKGROUND

The present article is an English-language version of the French National Diagnostic and Care Protocol, a pragmatic tool to optimize and harmonize the diagnosis, care pathway, management and follow-up of lymphangioleiomyomatosis in France.

METHODS

Practical recommendations were developed in accordance with the method for developing a National Diagnosis and Care Protocol for rare diseases of the Haute Autorité de Santé and following international guidelines and literature on lymphangioleiomyomatosis. It was developed by a multidisciplinary group, with the help of patient representatives and of RespiFIL, the rare disease network on respiratory diseases.

RESULTS

Lymphangioleiomyomatosis is a rare lung disease characterised by a proliferation of smooth muscle cells that leads to the formation of multiple lung cysts. It occurs sporadically or as part of a genetic disease called tuberous sclerosis complex (TSC). The document addresses multiple aspects of the disease, to guide the clinicians regarding when to suspect a diagnosis of lymphangioleiomyomatosis, what to do in case of recurrent pneumothorax or angiomyolipomas, what investigations are needed to make the diagnosis of lymphangioleiomyomatosis, what the diagnostic criteria are for lymphangioleiomyomatosis, what the principles of management are, and how follow-up can be organised. Recommendations are made regarding the use of pharmaceutical specialties and treatment other than medications.

CONCLUSION

These recommendations are intended to guide the diagnosis and practical management of pulmonary lymphangioleiomyomatosis.

Dynamic use of historical controls in clinical trials for rare disease research: A re-evaluation of the MILES trial

BACKGROUND

Randomized controlled trials offer the best design for eliminating bias in estimating treatment effects but can be slow and costly in rare disease research. Additionally, an equal randomization approach may not be optimal in studies in which prior evidence of superiority of one or more treatments exist. Supplementing prospectively enrolled, concurrent controls with historical controls can reduce recruitment requirements and provide patients a higher likelihood of enrolling in a new and possibly superior treatment arm. Appropriate methods need to be employed to ensure comparability of concurrent and historical controls to minimize bias and variability in the treatment effect estimates and reduce the chances of drawing incorrect conclusions regarding treatment benefit.

METHODS

MILES was a phase III placebo-controlled trial employing 1:1 randomization that led to US Food and Drug Administration approval of sirolimus for treating patients with lymphangioleiomyomatosis. We re-analyzed the MILES trial data to learn whether substituting concurrent controls with controls from a historical registry could have accelerated subject enrollment while leading to similar study conclusions. We used propensity score matching to identify exchangeable historical controls from a registry balancing the baseline characteristics of the two control groups. This allowed more new patients to be assigned to the sirolimus arm. We used trial data and simulations to estimate key outcomes under an array of alternative designs.

RESULTS

Borrowing information from historical controls would have allowed the trial to enroll fewer concurrent controls while leading to the same conclusion reached in the trial. Simulations showed similar statistical performance for borrowing as for the actual trial design without producing type I error inflation and preserving power for the same study size when concurrent and historical controls are comparable.

CONCLUSION

Substituting concurrent controls with propensity score-matched historical controls can allow more prospectively enrolled patients to be assigned to the active treatment and enable the trial to be conducted with smaller overall sample size, while maintaining covariate balance and study power and minimizing bias in response estimation. This approach does not fully eliminate the concern that introducing non-randomized historical controls in a trial may lead to bias in estimating treatment effects, and should be carefully considered on a case-by-case basis. Borrowing historical controls is best suited when conducting randomized controlled trials with conventional designs is challenging, as in rare disease research. High-quality data on covariates and outcomes must be available for candidate historical controls to ensure the validity of these designs. Additional precautions are needed to maintain blinding of the treatment assignment and to ensure comparability in the assessment of treatment safety.MILES ClinicalTrials.gov Number: NCT00414648.

Single-cell multiomic analysis identifies a HOX-PBX gene network regulating the survival of lymphangioleiomyomatosis cells

Lymphangioleiomyomatosis (LAM) is a rare, progressive lung disease that predominantly affects women. LAM cells carry TSC1/TSC2 mutations, causing mTORC1 hyperactivation and uncontrolled cell growth. mTORC1 inhibitors stabilize lung function; however, sustained efficacy requires long-term administration, and some patients fail to tolerate or respond to therapy. Although the genetic basis of LAM is known, mechanisms underlying LAM pathogenesis remain elusive. We integrated single-cell RNA sequencing and single-nuclei ATAC-seq of LAM lungs to construct a gene regulatory network controlling the transcriptional program of LAM cells. We identified activation of uterine-specific HOX-PBX transcriptional programs in pulmonary LAMCORE cells as regulators of cell survival depending upon HOXD11-PBX1 dimerization. Accordingly, blockage of HOXD11-PBX1 dimerization by HXR9 suppressed LAM cell survival in vitro and in vivo. PBX1 regulated STAT1/3, increased the expression of antiapoptotic genes, and promoted LAM cell survival in vitro. The HOX-PBX gene network provides promising targets for treatment of LAM/TSC mTORC1-hyperactive cancers.

Safety and Efficacy of Combined Resveratrol and Sirolimus in Lymphangioleiomyomatosis

BACKGROUND

A critical need exists to develop remission-inducing therapies for lymphangioleiomyomatosis.

RESEARCH QUESTION

Is the addition of resveratrol safe and more efficacious than sirolimus alone in patients with lymphangioleiomyomatosis?

STUDY DESIGN AND METHODS

We conducted a phase 2, dose-escalating, open-label trial of resveratrol in patients with lymphangioleiomyomatosis receiving a stable regimen of sirolimus. Resveratrol was started at 250 mg/d and escalated every 8 weeks to maximum dose of 1,000 mg/d over 24 weeks. The primary outcome was ≥ 42% decline in serum vascular endothelial growth factor D (VEGF-D) levels on combined therapy compared with baseline VEGF-D levels on sirolimus. Secondary objectives included an assessment of the safety profile and the effect on lung function and health-related quality of life (HRQOL). Longitudinal change in outcome measures was assessed using linear mixed models. Adverse effects were tabulated using the National Cancer Institute's Common Terminology Criteria for Adverse Events version 4.

RESULTS

Twenty-five patients with lymphangioleiomyomatosis with a median age of 51 years were enrolled. Pulmonary function parameters at study inclusion were: FEV1: median absolute, 1.72 L; 64% predicted; FVC: median absolute, 2.99 L; 96% predicted; and diffusing capacity of the lungs for carbon monoxide: median absolute, 14.68 mL/mm Hg/min; 37% predicted. The median serum VEGF-D value at baseline was 617 pg/mL. Patients entered the study with a median sirolimus dose of 2 mg/d with median trough level of 6.3 ng/mL. Despite some GI side effects, the addition of resveratrol was well tolerated. Although the primary outcome was not met, a statistically significant reduction in serum VEGF-D levels and improvement in HRQOL during the study was found.

INTERPRETATION

The addition of resveratrol was safe and well tolerated in patients with lymphangioleiomyomatosis taking sirolimus and was associated with modest improvement in HRQOL. Larger controlled trials of this combination might be warranted to assess definitively the usefulness of resveratrol as an additive therapy in lymphangioleiomyomatosis.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT03253913; URL: www.

CLINICALTRIALS

gov.

The benefit of indwelling pleural catheter with ambulatory pneumothorax device and autologous blood patch pleurodesis in lymphangioleiomyomatosis with persistent air leak

We report a 35-year-old woman who presented with dyspnoea and chest pain for 1 week. High-resolution computed tomography (HRCT) thorax revealed bilateral pneumothoraces with diffuse lung cysts. Bilateral intercostal chest tubes were inserted, and there was a persistent air leak (PAL) bilaterally. We performed an autologous blood patch pleurodesis (ABPP) for the left PAL. For the right PAL, she underwent a successful right video-assisted thoracic (VATS) surgery, wedge biopsy, and surgical pleurodesis. Histopathology examination confirmed the diagnosis of lymphangioleiomyomatosis (LAM). The left pneumothorax recurred. An indwelling pleural catheter (Rocket® IPC™; Rocket Medical plc; WASHINGTON) was inserted and the patient was discharged after 1 day with an atrium pneumostat (Pneumostat™; Atrium Medical Corporation, Hudson, NH, USA) chest drain valve. The patient was initiated on Sirolimus 2 mg daily. The left PAL resolved at 6 weeks. This case highlights the benefit of IPC with an ambulatory pneumothorax device in a patient with LAM with PAL.

Lymphangioleiomyomatosis: circulating levels of FGF23 and pulmonary diffusion

OBJECTIVE

Lymphangioleiomyomatosis (LAM) is a rare, destructive disease of the lungs with a limited number of determinants of disease activity, which are a critical need for clinical trials. FGF23 has been implicated in several chronic pulmonary diseases. We aimed to determine the association between serum FGF23 levels and pulmonary function in a cohort of patients with LAM.

METHODS

This was a descriptive single-center study in which subjects with LAM and controls with unreported lung disease were recruited. Serum FGF23 levels were measured in all subjects. Clinical data, including pulmonary function testing, were retrospectively obtained from electronic medical records of LAM subjects. Associations between FGF23 levels and clinical features of LAM were explored via nonparametric hypothesis testing.

RESULTS

The sample comprised 37 subjects with LAM and 16 controls. FGF23 levels were higher in the LAM group than in the control group. In the LAM group, FGF23 levels above the optimal cutoff point distinguished 33% of the subjects who had nondiagnostic VEGF-D levels. Lower FGF23 levels were associated with impaired DLCO (p = 0.04), particularly for those with isolated diffusion impairment with no other spirometric abnormalities (p = 0.04).

CONCLUSIONS

Our results suggest that FGF23 is associated with pulmonary diffusion abnormalities in LAM patients and elicit novel mechanisms of LAM pathogenesis. FGF23 alone or in combination with other molecules needs to be validated as a biomarker of LAM activity in future clinical research.

The world of rare interstitial lung diseases

The world of rare interstitial lung diseases (ILDs) is diverse and complex. Diagnosis and therapy usually pose challenges. This review describes a selection of rare and ultrarare ILDs including pulmonary alveolar proteinosis, pulmonary alveolar microlithiasis and pleuroparenchymal fibroelastosis. In addition, monogenic ILDs or ILDs in congenital syndromes and various multiple cystic lung diseases will be discussed. All these conditions are part of the scope of the European Reference Network on rare respiratory diseases (ERN-LUNG). Epidemiology, pathogenesis, diagnostics and treatment of each disease are presented.

An Evidence-Based Update on the Potential Association between Rheumatoid Arthritis and Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) represents an uncommon disorder characterized by cystic lung destruction and chronic respiratory failure. Lung damage caused by various mechanisms may represent a hypothesis for studying the association between LAM and rheumatoid arthritis (RA), which is the most prevalent autoinflammatory rheumatic disease and may affect the lungs as an extra-articular manifestation. Despite their distinct clinical presentations, the pathophysiology of both disorders includes dysregulated immunological function, abnormal cellular development, and inflammation. Current research suggests a potential relationship between RA and LAM, as some RA patients have been reported to develop LAM. However, the association of RA and LAM raises important therapeutic dilemmas. For this reason, the trajectory of a patient who was identified in our medical records as suffering from both LAM and RA, treated with many novel molecules and biological therapy, but with a negative outcome due to respiratory and multiorgan failure, has been exemplified. The delay in the diagnosis of LAM is due to a correlation between RA and LAM, worsening the vital prognosis and also hindering pulmonary transplantation. In addition, extensive research is essential for understanding the potential connection between these two disorders and discovering any similar mechanisms involved that may underlie their occurrence. This may contribute to the development of new therapeutic options that target shared pathways implicated in the pathogenesis of RA and LAM.

Determinants of Progression and Mortality in Lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis is a progressive diffuse cystic lung disease with approximately 85% survival at 10 years. The determinants of disease progression and mortality after the introduction of sirolimus therapy and vascular endothelial growth factor D (VEGF-D) as a biomarker have not been well defined.

RESEARCH QUESTION

Which factors, including VEGF-D and sirolimus therapy, influence disease progression and survival prognosis in patients with lymphangioleiomyomatosis?

STUDY DESIGN AND METHODS

The progression dataset and the survival dataset included 282 and 574 patients, respectively, from Peking Union Medical College Hospital, Beijing, China. A mixed-effects model was used to compute the rate of decline in FEV₁, and generalized linear models were used to identify variables affecting FEV₁ decline. A Cox proportional hazards model was used to explore the association between clinical variables and the outcomes of death or lung transplantation in patients with lymphangioleiomyomatosis.

RESULTS

VEGF-D levels and sirolimus treatment were associated with FEV₁ changes and survival prognosis. Compared with patients with VEGF-D of < 800 pg/mL at baseline, patients with VEGF-D of ≥ 800 pg/mL lost FEV₁ faster (SE, -38.86 mL/y; 95% CI, -73.90 to -3.82 mL/y; P = .031). The 8-year cumulative survival rates of patients with VEGF-D of ≥ 2,000 pg/mL and < 2,000 pg/mL were 82.9% and 95.1%, respectively (P = .014). The generalized linear regression model also demonstrated the benefit of delaying the decline of FEV₁ by 65.56 mL/y (95% CI, 29.06-102.06 mL/y) in patients treated with sirolimus compared with those without sirolimus (P < .001). The 8-year risk of death was reduced by 85.1% (hazard ratio, 0.149; 95% CI, 0.075-0.299) after sirolimus treatment. After inverse treatment probability weighting, the risks of death in the sirolimus group were reduced by 85.6%. CT scan results of grade III severity were associated with worse progression than results of grades I or II severity. Patients with baseline FEV₁ of 70% predicted or St. George's Respiratory Questionnaire Symptoms domain 50 or higher predicted a higher risk of worse survival.

INTERPRETATION

Serum VEGF-D levels, a biomarker of lymphangioleiomyomatosis, are associated with disease progression and survival. Sirolimus therapy is associated with slower disease progression and better survival in patients with lymphangioleiomyomatosis.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT03193892; URL: www.

CLINICALTRIALS

gov.

Lymphangioleiomyomatosis: a metastatic lung disease

Lymphangioleiomyomatosis (LAM) is a rare disease affecting women, caused by somatic mutations in the TSC1 or TSC2 genes, and driven by estrogen. Similar to many cancers, it is metastatic, primarily to the lung. Despite its monogenetic nature, like many cancers, LAM is a heterogeneous disease. The cellular constituents of LAM are very diverse, including mesenchymal, epithelial, endothelial, and immune cells. LAM is characterized by dysregulation of many cell signaling pathways, distinct populations of LAM cells, and a rich microenvironment, in which the immune system appears to play an important role. This review delineates the heterogeneity of LAM and focuses on the metastatic features of LAM, the deregulated signaling mechanisms and the tumor microenvironment. Understanding the tumor-host interaction in LAM may provide insights into the development of new therapeutic strategies, which could be combinatorial or superlative to Sirolimus, the current U.S. Food and Drug Administration-approved treatment.

Disease monitoring using lung function trajectory in lymphangioleiomyomatosis: assessment in two national cohorts

STUDY QUESTION

In lymphangioleiomyomatosis, airflow obstruction and impairment of gas transfer progress at variable rates and serial lung function is recommended for disease monitoring. As these measurements are variable, recognising subjects needing treatment can be difficult. We used two prospective national cohorts to study change over time and variation in FEV₁ to inform clinical decision making.

PATIENTS AND METHODS

Clinical and lung function data for 141 UK and 148 American subjects were studied. Multilevel mixed effects modelling, route mean square analysis of errors and Bland-Altman analysis were used to analyse variability in lung function over time.

RESULTS

At baseline assessment, DL_CO was reduced to a greater degree than FEV₁. In untreated patients, FEV₁ and DL_CO declined at proportionately similar rates independent of initial lung function. In mechanistic target of rapamycin (mTOR) inhibitor treated patients, FEV₁ stabilised but DL_CO continued to decline. FEV₁/DL_CO per cent predicted ratio was 1.37 (0.43) at baseline and increased to 1.41 (0.50) after 42 (24) months (p=0.0002). At least five measurements were required before >70% of individuals had estimates of rate of FEV₁ loss within 50 mL/year and DL_CO loss within 0.1 mmol/min/kPa/year of the final values.

CONCLUSIONS

While FEV₁ and DL_CO fall proportionately in most, in early disease and during mTOR inhibitor treatment, DL_CO should also be monitored as it may fall independent of FEV₁. Since at least five observations over many months are required to make confident estimates of FEV₁ and DL_CO trajectories, new strategies are needed to measure disease activity and target early treatment appropriately.

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.