Changes in lung function and chylous effusions in patients with lymphangioleiomyomatosis treated with sirolimus

mTOR pathway diseases: challenges and opportunities from bench to bedside and the mTOR node

Mechanistic target of rapamycin (mTOR) is a highly conserved serine/threonine kinase that regulates key cellular processes including cell growth, autophagy and metabolism. Hyperactivation of the mTOR pathway causes a group of rare and ultrarare genetic diseases. mTOR pathway diseases have diverse clinical manifestations that are managed by distinct medical disciplines but share a common underlying molecular basis. There is a now a deep understanding of the molecular underpinning that regulates the mTOR pathway but effective treatments for most mTOR pathway diseases are lacking. Translating scientific knowledge into clinical applications to benefit the unmet clinical needs of patients is a major challenge common to many rare diseases. In this article we expound how mTOR pathway diseases provide an opportunity to coordinate basic and translational disease research across the group, together with industry, medical research foundations, charities and patient groups, by pooling expertise and driving progress to benefit patients. We outline the germline and somatic mutations in the mTOR pathway that cause rare diseases and summarise the prevalence, genetic basis, clinical manifestations, pathophysiology and current treatments for each disease in this group. We describe the challenges and opportunities for progress in elucidating the underlying mechanisms, improving diagnosis and prognosis, as well as the development and approval of new therapies for mTOR pathway diseases. We illustrate the crucial role of patient public involvement and engagement in rare disease and mTOR pathway disease research. Finally, we explain how the mTOR Pathway Diseases node, part of the Research Disease Research UK Platform, will address these challenges to improve the understanding, diagnosis and treatment of mTOR pathway diseases.

Influence of preoperative nutritional status on postoperative dysphagia in lung transplantation

OBJECTIVES

The purpose of this study is to determine the effect of preoperative nutritional status on the severity of postoperative dysphagia in recipients undergoing lung transplantation (LTx).

METHODS

A retrospective analysis was conducted. Preoperative nutritional status was assessed using the Controlling Nutritional Status (CONUT) score and the Global Leadership Initiative on Malnutrition (GLIM) criteria. Dysphagia on postoperative day 14 was evaluated using the Functional Oral Intake Scale (FOIS). Study variables included age, sex, type of LTx, duration of intensive care unit stay, duration of mechanical ventilation use, duration of surgery, tracheostomy, extracorporeal membrane oxygen therapy (ECMO), pulmonary arterial hypertension (PAH), CONUT score, and GLIM criteria. Binary logistic regression (BLR) was used to assess independent factors.

RESULTS

Among 65 recipients (31 females, mean age 43.4 ± 12.0 years), postoperative dysphagia (n = 39) was associated with younger age (P < 0.001), female sex (P = 0.026), double LTx (P < 0.001), longer ICU stay (P < 0.001), longer mechanical ventilation use (P < 0.001), longer duration of surgery (P < 0.001), need of tracheostomy (P < 0.001), use of ECMO (P < 0.001), PAH diagnosis (P = 0.005), higher CONUT score (P < 0.001), and malnutrition by GLIM criteria (P = 0.031). Preoperative CONUT score was the only independent factor by BLR (P = 0.026, OR = 0.221, 95% CI: 0.059-0.837).

CONCLUSIONS

Our findings suggest that preoperative nutritional status may be important for the preservation of postoperative swallowing function in LTx.

Surgical management of pleural complications in lymphangioleiomyomatosis

OBJECTIVE

Lymphangioleiomyomatosis (LAM) is a rare cystic lung disease occurring primarily in women. Pneumothorax and chylothorax are common pleural complications in LAM. We aim to explore various options in the surgical management of pleural disease in LAM.

METHODS

A retrospective chart review of all patients at the Center for LAM and Rare Lung Diseases at Columbia University was performed, and date, type, and indication for surgical procedure were collected. All patients with any cystic lung disease seen between January 1, 2000, and March 1, 2023, were included in the database.

RESULTS

The charts for 326 patients with possible LAM were reviewed, including 213 with confirmed LAM and 113 women with cystic lung disease consistent suspected to be LAM were reviewed. A total of 40.5% underwent surgical procedures at our institution or at referring hospitals. A total of 15.6% of patients underwent surgical lung biopsies. A total of 16.6% had a history of pneumothoraces, of whom 79.6% underwent chemical and/or mechanical pleurodesis, 14.8% required pleurectomy, and 7.4% were discharged with tunneled indwelling pleural catheters. We found that 5.6% of confirmed LAM patients have history of chylothorax, with thoracic duct ligation, thoracic duct embolization, pleurodesis, and pleurodesis with long-term tunneled indwelling pleural catheter placement all used as treatment strategies.

CONCLUSIONS

Here we demonstrate the significant burden of pleural disease in patients with LAM. It is imperative that thoracic surgeons understand the high incidence of pneumothorax in this patient population. Tunneled indwelling pleural catheters are underutilized but provide long-term options for chylous management with long-term mechanical pleurodesis and a decrease in hospital length of stay.

Illness cognition, illness perception and related factors in patients with lymphangioleiomyomatosis

PURPOSE

To explore the self-perceived illness cognition and perception status, as well as the relevant factors among lymphangioleiomyomatosis (LAM) patients.

METHODS

A web-based questionnaire survey was conducted in September 2023. A total of 121 LAM patients participated (including 16 patients with TSC-LAM), and the survey collected general demographic information, responses to a disease cognition questionnaire, and a simplified disease perception questionnaire.

RESULTS

LAM patients have a higher level of negative illness cognition and a lower level of positive illness cognition, specifically characterized by helplessness (15.74 ± 4.68 points), acceptance (16.00 ± 3.28 points), and perceived benefits (16.92 ± 3.86 points). Single-factor analysis of variance found significant correlations between cultural level, age, family average monthly income, use of rapamycin, use of home oxygen therapy, hospitalization frequency, disease duration, severity of respiratory distress, activity limitation, and the helplessness score of LAM patients (p ≤ 0.05); the number of children was significantly associated with acceptance scores of LAM patients (p ≤ 0.05); and whether surgery had been performed was significantly associated with acceptance and perceived benefits scores of LAM patients (p ≤ 0.05). Disease duration and activity limitation entered the regression equation for helplessness dimension, while whether surgery had been performed entered the regression equation for perceived benefits dimension, but no factor entered the regression equation for acceptance dimension. Applying the same analysis to disease perception, we found that the average score of the Illness Perception Questionnaire was 45.43 ± 8.97, with lower scores in the reverse-scored items of individual control, treatment, and understanding.

CONCLUSIONS

LAM patients exhibit higher levels of helplessness, particularly among those with longer disease duration and greater activity limitations, leading to a more negative perception of the disease. Additionally, patients who have undergone surgical procedures tend to perceive fewer benefits. Furthermore, there is a significant correlation between illness perception and factors such as rapamycin usage, home oxygen therapy, disease duration and activity limitations caused by LAM. This indicates that clinical healthcare providers should pay more attention to LAM patients and their associated groups, providing both informational and psychological support.

Brazilian Thoracic Association recommendations for the management of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare disease, characterized as a low-grade neoplasm with metastatic potential that mainly affects women of reproductive age, in which there is proliferation of atypical smooth muscle cells (LAM cells) and formation of diffuse pulmonary cysts. It can occur in a sporadic form or in combination with tuberous sclerosis complex. In recent decades, a number of advances have been made in the understanding of the pathophysiology and management of LAM, leading to improvements in its prognosis: identification of the main genetic aspects and the role of the mechanistic target of rapamycin (mTOR) pathway; relationship with hormonal factors, mainly estrogen; characterization of pulmonary and extrapulmonary manifestations in imaging studies; identification and importance in the diagnosis of VEGF-D; a systematic diagnostic approach, often without the need for lung biopsy; use of and indications for the use of mTOR inhibitors, mainly sirolimus, for pulmonary and extrapulmonary manifestations; pulmonary rehabilitation and the management of complications such as pneumothorax and chylothorax; and the role of and indications for lung transplantation. To date, no Brazilian recommendations for a comprehensive approach to the disease have been published. This document is the result of a non-systematic review of the literature, carried out by 12 pulmonologists, a radiologist, and a pathologist, which aims to provide an update of the most important topics related to LAM, mainly to its diagnosis, treatment, and follow-up, including practical and multidisciplinary aspects of its management.

PEComas: A review of imaging and clinical features

Perivascular epithelioid cell tumors (PEComas) are a group of rare mesenchymal tumors, which demonstrate varied imaging appearances and treatment options. These tumors may arise de novo or in the setting of systemic disorders, such as tuberous sclerosis. Some PEComas are benign and easily resected while others may represent systemic or metastatic disease with limited therapeutic options. The purpose of this review is to introduce the topic of perivascular epithelioid cell tumors and the most common tumors within the PEComa family as well as discuss the epidemiology, morphology, radiographic appearance, and treatment options of these rare tumors.

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.

A chylothorax in a young woman: The difficulties of medical management

Lymphangioleiomyomatosis is a rare pulmonary disease affecting women of childbearing age. Whilst chylothorax is a well-recognized complication of the condition, management strategies aren't well-defined, have low success rates and are often only available at tertiary or specialist centres. We describe a case of a young woman referred to pleural clinic with a chylous effusion found to be secondary to lymphangioleiomyomatosis. Initial medical management was unsuccessful and recurrent drainages caused significant complications. Remission was ultimately achieved with a combination of mTOR inhibitors and interventional radiology techniques.

Tissue-Engineered Disease Modeling of Lymphangioleiomyomatosis Exposes a Therapeutic Vulnerability to HDAC Inhibition

Lymphangioleiomyomatosis (LAM) is a rare disease involving cystic lung destruction by invasive LAM cells. These cells harbor loss-of-function mutations in TSC2, conferring hyperactive mTORC1 signaling. Here, tissue engineering tools are employed to model LAM and identify new therapeutic candidates. Biomimetic hydrogel culture of LAM cells is found to recapitulate the molecular and phenotypic characteristics of human disease more faithfully than culture on plastic. A 3D drug screen is conducted, identifying histone deacetylase (HDAC) inhibitors as anti-invasive agents that are also selectively cytotoxic toward TSC2-/- cells. The anti-invasive effects of HDAC inhibitors are independent of genotype, while selective cell death is mTORC1-dependent and mediated by apoptosis. Genotype-selective cytotoxicity is seen exclusively in hydrogel culture due to potentiated differential mTORC1 signaling, a feature that is abrogated in cell culture on plastic. Importantly, HDAC inhibitors block invasion and selectively eradicate LAM cells in vivo in zebrafish xenografts. These findings demonstrate that tissue-engineered disease modeling exposes a physiologically relevant therapeutic vulnerability that would be otherwise missed by conventional culture on plastic. This work substantiates HDAC inhibitors as possible therapeutic candidates for the treatment of patients with LAM and requires further study.

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.

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.

Upregulation of acid ceramidase contributes to tumor progression in tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is characterized by multisystem, low-grade neoplasia involving the lung, kidneys, brain, and heart. Lymphangioleiomyomatosis (LAM) is a progressive pulmonary disease affecting almost exclusively women. TSC and LAM are both caused by mutations in TSC1 and TSC2 that result in mTORC1 hyperactivation. Here, we report that single-cell RNA sequencing of LAM lungs identified activation of genes in the sphingolipid biosynthesis pathway. Accordingly, the expression of acid ceramidase (ASAH1) and dihydroceramide desaturase (DEGS1), key enzymes controlling sphingolipid and ceramide metabolism, was significantly increased in TSC2-null cells. TSC2 negatively regulated the biosynthesis of tumorigenic sphingolipids, and suppression of ASAH1 by shRNA or the inhibitor ARN14976 (17a) resulted in markedly decreased TSC2-null cell viability. In vivo, 17a significantly decreased the growth of TSC2-null cell-derived mouse xenografts and short-term lung colonization by TSC2-null cells. Combined rapamycin and 17a treatment synergistically inhibited renal cystadenoma growth in Tsc2+/- mice, consistent with increased ASAH1 expression and activity being rapamycin insensitive. Collectively, the present study identifies rapamycin-insensitive ASAH1 upregulation in TSC2-null cells and tumors and provides evidence that targeting aberrant sphingolipid biosynthesis pathways has potential therapeutic value in mechanistic target of rapamycin complex 1-hyperactive neoplasms, including TSC and LAM.

Lymphangioleiomyomatosis and Other Cystic Lung Diseases

Cysts and cavities in the lung are commonly encountered on chest imaging. It is necessary to distinguish thin-walled lung cysts (≤2 mm) from cavities and characterize their distribution as focal or multifocal versus diffuse. Focal cavitary lesions are often caused by inflammatory, infectious, or neoplastic processes in contrast to diffuse cystic lung diseases. An algorithmic approach to diffuse cystic lung disease can help narrow the differential diagnosis, and additional testing such as skin biopsy, serum biomarkers, and genetic testing can be confirmatory. An accurate diagnosis is essential for the management and disease surveillance of extrapulmonary complications.

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.

Computer grading of lung disease severity in patients with lymphangioleiomyomatosis referred for transplantation

Objectives

Lymphangioleiomyomatosis (LAM) patients with severe lung disease may be considered for lung transplantation. Clinical, physiologic, and quality of life data are usually employed for referral. The aim of this study was to determine whether computed tomographic measurement of lung volume occupied by cysts (cyst score) complemented clinical and physiologic data in supporting referral for transplantation.

Methods

Forty-one patients were studied. Pre-referral clinical data, pulmonary function tests, exercise testing, and high-resolution computed tomography (HRCT) scans were obtained. From HRCT, a computer-aided diagnostic program was employed to calculate cyst scores. These data were compared to those of 41 age-matched LAM patients not referred for lung transplantation.

Results

Cyst score, and % predicted FEV1 and DLCO were respectively, 48.1 ± 9.4%, 36.5 ± 9.1%, and 35.0 ± 10.7%. For the control group, cyst score, FEV1, and DLCO were respectively, 14.8 ± 8.3%, 77.2 ± 20.3%, and 66.7 ± 19.3%. Cyst score values showed a normal distribution. However, the frequency distribution of FEV1 was skewed to the right while the distribution of DLCO was bimodal. Correlations between cyst score and FEV1 and DLCO for the study group were respectively, r = − 0.319 and r = − 0.421.

Conclusions

LAM patients referred for lung transplantation had nearly 50% of lungs occupied by cysts. Correlations between cyst score and FEV1 or DLCO were weak; as shown previously, DLCO was better related to cyst number while FEV1 had a better association with cyst size. Given its normal distribution, cyst score measurements may assist in evaluation of pre-transplant severity of lung disease before referral for transplantation.

Imaging Findings of Thoracic Lymphatic Abnormalities

The lymphatic system plays an important role in balancing fluid compartments in the body. It is disrupted by various disease processes in the thorax, including injury to the thoracic lymphatic duct after surgery, as well as malignancy and heart failure. Because of the small size of lymphatic vessels, imaging of the lymphatics is relatively difficult, and effective imaging methods are still being optimized and developed. The standard of reference for lymphatic imaging has been conventional lymphangiography for several decades. Other modalities such as CT, noncontrast or contrast-enhanced MRI, and lymphoscintigraphy can also demonstrate lymphatic abnormalities and help in treatment planning. Imaging findings associated with lymphatic abnormalities can be seen in the pulmonary parenchyma, pleural space, and mediastinum. In the pulmonary parenchyma, common findings include interlobular septal thickening as well as reversal of lymphatic flow with intravasation of contrast material into pulmonary lymphatics. In the pleural space, findings include chylous pleural effusion and occasionally nonchylous pleural effusion. In the mediastinum, thoracic duct leak, plexiform thoracic duct, lymphatic malformations, and lymphangiectasis may occur. Management of chylothorax includes conservative or medical treatment, surgery, and interventional radiology procedures. The authors discuss thoracic lymphatic anatomy, imaging manifestations of lymphatic abnormalities in the various anatomic compartments, and interventional radiology treatment of chylothorax. Radiologists should be familiar with these imaging findings for diagnosis and to help guide appropriate management. ^©RSNA, 2022.

Long-term clinical course and outcomes in patients with lymphangioleiomyomatosis

Background

Lymphangioleiomyomatosis (LAM) is a rare multisystemic disorder with various clinical manifestations. Despite the recognition of several prognostic factors, the long-term clinical course and prognosis of patients with LAM in the era of sirolimus therapy are not established.

Methods

The clinical data of 104 patients with LAM were retrospectively analyzed. Death or lung transplantation was defined as the primary outcome. Disease progression (DP) was defined as a 10% absolute decline in forced expiratory volume in one second (FEV₁).

Results

The mean age of all patients was 40.3 years. Over a median follow-up period of 7.1 years, of all patients, 6.7% died and 1.9% underwent lung transplantation, while of 92 patients with serial lung function data, 35.9% experienced DP. The 5-year and 10-year overall survival rates were 93.0% and 90.9%, respectively. The multivariable Cox analysis revealed that older age (hazard ratio [HR]: 1.136, P = 0.025), lower FEV₁ (HR: 0.956, P = 0.026) or diffusing capacity for carbon monoxide (HR: 0.914, P = 0.003), and shorter distance during the 6-min walk test (HR: 0.993, P = 0.020) were independent prognostic factors for mortality. A propensity score-matched comparative analysis performed between patients who received sirolimus therapy and those who did not, found no differences in survival, DP, complications, and lung function decline rate.

Conclusions

Over a follow-up period of approximately 7 years, one-tenth of all patients experienced death, while one-third experienced DP. Older age, lower lung function, and reduced exercise capacity were associated with a poor prognosis in patients with LAM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02079-6.

Long-term clinical course and progression of lymphangioleiomyomatosis in a single lung transplant referral centre in Korea

We aimed to describe the clinical features of lymphangioleiomyomatosis (LAM) in Korean patients and identify factors associated with progressive disease (PD). Clinical features of 54 patients with definite or probable LAM from 2005 to 2018 were retrospectively analysed. Common features were pneumothorax (66.7%) and abdominal lymphadenopathy (50.0%). Twenty-three (42.6%) patients were initially treated with mechanistic target of rapamycin (mTOR) inhibitors. Lung transplantation (LT) was performed in 13 (24.1%) patients. Grouped based on the annual decline in forced expiratory volume in 1 s (FEV₁) from baseline and LT, 36 (66.7%) patients exhibited stable disease (SD). All six deaths (11.1%) occurred in PD. Proportion of SD was higher in those treated initially with mTOR inhibitors than in those under observation (p = 0.043). Univariate analysis revealed sirolimus use, and baseline forced vital capacity, FEV₁, and diffusing capacity of the lungs for carbon monoxide are associated with PD. Multivariate analysis showed that only sirolimus use (odds ratio 0.141, 95% confidence interval 0.021-0.949, p = 0.044) reduced PD. Kaplan-Meier analysis estimates overall survival of 92.0% and 74.7% at 5 and 10 years, respectively. A considerable proportion of LAM patients remain clinically stable without treatment. LT is an increasingly viable option for patients with severe lung function decline.

Perfect match: mTOR inhibitors and tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal dominant syndrome that presents with diverse and complex clinical features and involves multiple human systems. TSC-related neurological abnormalities and organ dysfunction greatly affect the quality of life and can even result in death in patients with TSC. It is widely accepted that most TSC-related clinical manifestations are associated with hyperactivation of the mammalian target of rapamycin (mTOR) pathway caused by loss‑of‑function mutations in TSC1 or TSC2. Remarkable progress in basic and translational research has led to encouraging clinical advances. Although mTOR inhibitors (rapamycin/everolimus) demonstrate great potential in TSC management, two major concerns hamper their generalized application. One is the frequent manifestation of adverse events, such as stomatitis, infections, and menstrual disorders; and the other is the poor response in certain patients. Thus, indicators are required to effectively predict the efficacy of mTOR inhibitors. Herein, we have summarized the current utilization of mTOR inhibitors in the treatment of TSC and focused on their efficacy and safety, in an attempt to provide a reference to guide the treatment of TSC.

Hyperactivation of mammalian target of rapamycin (mTOR) is essential in the pathogenesis of tuberous sclerosis complex (TSC) and can serve as a therapeutic target.

mTOR inhibitors have shown considerable success in multiple clinical trials for the treatment of TSC, including neurological, pulmonary, cardiac, renal, and cutaneous phenotypes.

mTOR inhibitors are associated with adverse events, which should be considered during the management of TSC.

Indicators to predict mTOR inhibitor efficacy are required to select patients who are likely to benefit from such therapy.

Chylothorax and Pseudochylothorax

Classically, both chylothorax and pseudochylothorax present as a pleural effusion with a characteristic milky white appearance to the pleural fluid. Although both are rare causes of pleural effusion, they have distinct etiologies and clinical implications, and as a result require different management strategies. Pleural fluid analysis of cholesterol and triglyceride levels is key to differentiating the 2 entities from one another and then guide the clinician to determine the best next steps in evaluation and management.

Reduced risk of recurrent pneumothorax for sirolimus therapy after surgical pleural covering of entire lung in lymphangioleiomyomatosis

Background

Patients with lymphangioleiomyomatosis (LAM) frequently experience pneumothorax. Although sirolimus is the standard therapy for LAM, its effect on pneumothorax is controversial. Recently, total pleural covering (TPC) and modified TPC (mTPC) were introduced as surgical treatment options for pneumothorax for patients with LAM. However, the effect of sirolimus on the recurrence of pneumothorax in patients who underwent the treatments is still uncertain. We hypothesized that some clinical factors including sirolimus treatment could predict postoperative recurrence of pneumothorax. In order to clarify this hypothesis, we retrospectively analyzed the clinical data from 18 consecutive patients with LAM who underwent 24 surgical pleural covering of entire lung (SPC) as 17 TPC and 7 mTPC against pneumothoraces from surgical database between January 2005 and January 2019, and we determined the predictors of postoperative recurrence.

Results

Of the 24 surgeries of SPC, 14 surgeries (58.3%) had a history of two or more ipsilateral pneumothoraces, and 11 surgeries (45.8%) had a history of ipsilateral pleural procedures before SPC. Sixteen surgeries (66.6%) in 12 patients received treatment of sirolimus after SPC (sirolimus group). With a median follow-up time of 69.0 months after SPC, four surgeries (16.6%) in three patients had a postoperative recurrence, and the 5-year recurrence-free survival (RFS) after SPC was 82.9%. In patients with postoperative recurrence, serum level of vascular endothelial growth factors D was significantly higher than that in those with non-recurrence (3260.5 vs. 892.7 pg/mL, p = 0.02), and the rate of sirolimus treatment in the recurrence group was significantly lower than that in the no-recurrence group (0 vs. 80%, p = 0.006). The log-rank test showed that the RFS of the sirolimus group (sirolimus use after SPC) was significantly better than that of the non-sirolimus group (p = 0.001), and no significant difference was observed for other factors.

Conclusion

We first reported sirolimus might effectively suppress the recurrence of pneumothoraces in LAM patients who received SPC. Sirolimus induction after SPC (TPC or mTPC) might be a feasible option for frequent pneumothorax in LAM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-02081-z.

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.

Recycling plastic: diagnosis and management of plastic bronchitis among adults

Plastic bronchitis is a rare, underdiagnosed and potentially fatal condition. It is characterised by the formation and expectoration of branching gelatinous plugs that assume the shape of the airways. These airway plugs differ from the allergic mucin that characterises allergic bronchopulmonary aspergillosis and mucoid impaction of the bronchi. Plastic bronchitis is most often encountered in the paediatric population following corrective cardiac surgery, such as the Fontan procedure. It also occurs in adults. Plastic bronchitis in adults is rare, heterogeneous in its aetiology, and can lead to respiratory distress or even life-threatening airway obstruction. Plastic bronchitis in adulthood should not be overlooked, particularly in patients with chronic inflammatory lung diseases. This review presents current understanding of the presentation, aetiology, pathogenesis, pathology and management of plastic bronchitis in adults.

Sclerosi tuberosa ed everolimus: una nuova storia

Tuberous sclerosis complex (TSC) is a rare autosomal dominant disorder, due to inactivating muta-tions of TSC1 or TSC2 mTOR pathway genes and is characterized by variable multisystem manifestations ranging from hamartomas to malignant neoplasms. It frequently associated to seizures, intellectual disability and behavioural disorders. Surgical treatment has traditionally been used to manage subependymal giant cells astrocytomas (SEGA). The introduction of mTOR inhibitor rapamycin, with its definite role both as primary and as adjuvant treatment, has significantly modified the management opportunities in the clinical practice. It is important to consider both treatment options in a balanced way and not only the SEGA, but also the individual patient and their associated comorbidities. The pros and the cons of both options should be discussed by a multidisciplinary team before establishing an individualized treatment recommendation. The paper reports the case of a patient with an asymptomatic SEGA who was treated with everolimus. The treatment was effective in reducing the size of the tumour, it was safe and well tolerated.

Long-Term Effects of Sirolimus on Human Skin TSC2-Null Fibroblast‒Like Cells

Tuberous sclerosis complex (TSC) is an autosomal-dominant disorder characterized by hamartomatous tumors of the skin, kidneys, brain, and lungs. TSC is caused by mutations in the TSC1 and TSC2 genes, which result in hyperactivation of the mTOR, leading to dysregulated cell growth and autophagy. Rapamycin (sirolimus) shrinks TSC tumors, but the clinical benefits of sirolimus are not sustained after its withdrawal. In this study, we studied the cellular processes critical for tumor formation and growth, including cell proliferation and cell size. TSC2^-/- and TSC2^+/- cells were isolated from TSC skin tumors and normal-appearing skin, respectively. Cells were incubated with sirolimus for 72 hours. Withdrawal of sirolimus from TSC2^-/- cells resulted in a highly proliferative phenotype and caused cells to enter the S phase of the cell cycle, with persistent phosphorylation of mTOR, p70 S6 kinase, ribosomal protein S6, and 4EB-P1; decreased cyclin D kinase inhibitors; and transient hyperactivation of protein kinase B. Sirolimus modulated the estrogen- and autophagy-dependent volume of TSC2^-/- cells. These results suggest that sirolimus may decrease the size of TSC tumors by reducing TSC2^-/- cell volume, altering the cell cycle, and reprogramming TSC2-null cells.

Tuberous sclerosis complex for the pulmonologist

Tuberous sclerosis complex (TSC) is a rare multisystem genetic disorder affecting almost all organs with no sex predominance. TSC has an autosomal-dominant inheritance and is caused by a heterozygous mutation in either the TSC1 or TSC2 gene leading to hyperactivation of the mammalian target of rapamycin (mTOR). TSC is associated with several pulmonary manifestations including lymphangioleiomyomatosis (LAM), multifocal micronodular pneumocyte hyperplasia (MMPH) and chylous effusions. LAM is a multisystem disorder characterised by cystic destruction of lung parenchyma, and may occur in either the setting of TSC (TSC-LAM) or sporadically (S-LAM). LAM occurs in 30–40% of adult females with TSC at childbearing age and is considered a nonmalignant metastatic neoplasm of unknown origin. TSC-LAM is generally milder and, unlike S-LAM, may occur in males. It manifests as multiple, bilateral, diffuse and thin-walled cysts with normal intervening lung parenchyma on chest computed tomography. LAM is complicated by spontaneous pneumothoraces in up to 70% of patients, with a high recurrence rate. mTOR inhibitors are the treatment of choice for LAM with moderately impaired lung function or chylous effusion. MMPH, manifesting as multiple solid and ground-glass nodules on high-resolution computed tomography, is usually harmless with no need for treatment.

Tuberous sclerosis complex is associated with diverse pulmonary manifestations including LAM, multiple micronodular pneumocyte hyperplasia and chylous effusions. LAM occurs in 30–40% of adult females with tuberous sclerosis complex.https://bit.ly/3iLqZ08

A breathless teenager

A 14-year-old girl presented to hospital with breathlessness and fatigue. On admission she was hypoxaemic with oxygen saturations of 90%, tachycardic with a heart rate of 120 beats·min⁻¹ and tachypnoeic with a respiratory rate of 40–50 breaths·min⁻¹.

In children with persistent chylothoraces of unknown origin, intranodal lymphangiography can be used to help identify the source of a leak. This may enable embolisation with glue and coils to enable resolution of the chylothoraces.https://bit.ly/3gskhgJ

Improving Survival in Lymphangioleio-myomatosis: A 16-Year Observational Study in a Large Cohort of Patients

BACKGROUND

Over the last 2 decades, great progress has been made in the understanding of the clinical aspects and pathogenesis of lymphangioleiomyomatosis (LAM), leading to publication of guidelines and approval of an effective therapy.

OBJECTIVES

Aim of our study was to describe how the management and the natural history of this rare disease have changed after the publication of the ERS and American Thoracic Society/Japanese Respiratory Society guidelines and the introduction of sirolimus.

METHODS

We examined 162 LAM patients followed at our center between 2001 and 2017, reporting clinical characteristics and diagnostic approach. Response to sirolimus in patients undergoing long-term treatment and mortality risk, estimated in terms of cumulative incidence taking into account organ transplantation as a competing cause of the event, were evaluated. The difference in the cumulative incidence between the patients admitted to the observation before 2011 and after 2011, year of the publication of the MILES trial for the efficacy of sirolimus, has also been estimated.

RESULTS

Sixty-one patients had a histological diagnosis (22 from 2010 onward). 101 patients received a radiological diagnosis according to the guidelines criteria. Pulmonary function tests remained stable over a 3-year treatment period in patients who received sirolimus for over 12 months. The cumulative incidence of mortality after 10 years in the whole population was 25.5%. The cumulative incidence of mortality after 5 years was significantly lower in patients who entered the study since 2011 (after publication of the MILES trial) than in patients who entered the study before.

CONCLUSIONS

We provide the data supporting the long-term efficacy of sirolimus therapy in a large cohort of patients with functional impairment and other manifestations of the disease. Our results also suggest that the advent of sirolimus and the publication of international guidelines changed the natural history of the disease lowering the mortality and reducing the need of invasive diagnostic techniques.

Possible Novel Therapeutic Targets in Lymphangioleiomyomatosis Treatment

Lymphangioleiomyomatosis (LAM) is a rare systemic neoplastic disease that exclusively happens in women. Studies focusing on LAM and tuberous sclerosis complex (TSC) have made great progress in understanding the pathogenesis and searching for treatment. The inactive mutation of TSC1 or TSC2 is found in patients with LAM to activate the crucial mammalian target of rapamycin (mTOR) signaling pathway and result in enhanced cell proliferation and migration. However, it does not explain every step of tumorigenesis in LAM. Because cessation of rapamycin would break the stabilization of lung function or improved quality of life and lead to disease recurrent, continued studies on the pathogenesis of LAM are necessary to identify novel targets and new treatment. Researchers have found several aberrant regulations that affect the mTOR pathway such as its upstream or downstream molecules and compensatory pathways in LAM. Some therapeutic targets have been under study in clinical trials. New methods like genome-wide association studies have located a novel gene related to LAM. Herein, we review the current knowledge regarding pathogenesis and treatment of LAM and summarize novel targets of therapeutic potential recently.

Ultra-rare cystic disease

Diffuse cystic lung diseases include a group of heterogeneous disorders characterised by the presence of cysts within the lung parenchyma, sometimes showing a characteristic computed tomography scan pattern that allows diagnosis. The pathogenetic mechanisms underlying cyst formation in the lung are still not clear and a number of hypotheses have been postulated according to the different aetiologies: ball-valve effect, ischaemic dilatation of small airways and alveoli related to infiltration and obstruction of small vessels and capillaries that supply the terminal bronchioles and connective tissue degradation by matrix metalloproteases. A wide number of lung cyst diseases have been classified into six diagnostic groups according to the aetiology: neoplastic, congenital/genetic, lymphoproliferative, infective, associated with interstitial lung diseases, and other causes. This article focuses on lymphangioleiomyomatosis, pulmonary Langerhans cell histiocytosis and Erdheim–Chester disease, Birt–Hogg–Dubé, follicular bronchiolitis and lymphocytic interstitial pneumonia, light-chain deposition disease and amyloidosis, congenital lung disease associated with aberrant lung development and growth, and cystic lung disease associated with neoplastic lesion. These cystic diseases are epidemiologically considered as ultra-rare conditions as they affect fewer than one individual per 50 000 or fewer than 20 individuals per million. Despite the rarity of this group of disorders, the increasing use of high-resolution computed tomography has improved the diagnostic yield, even in asymptomatic patients allowing prompt and correct therapy and management without the need for a biopsy.

Diffuse cystic lung diseases show a characteristic CT scan pattern that often allows for diagnosis, even in asymptomatic patients, allowing prompt correct therapy and management without the needing of a biopsyhttps://bit.ly/2wIUKet

Refractory chylous effusions in lymphangioleiomyomatosis patient post lung transplant

Lymphangioleiomyomatosis is a rare systemic disorder of unknown etiology that affects young women almost exclusively. Chylous effusions are known to be associated with lymphangioleiomyomatosis and may be difficult to treat. We present the case of a 37-year-old female who received bilateral lung transplantation for lymphangioleiomyomatosis complicated by refractory chylothorax and chylous ascites, ultimately controlled through repeated, open surgical procedures and percutaneous lymphatic embolization interventions. The combined surgical and interventional radiological approach, while not novel in their own right, suggests that a multi-modal interventional approach may be required in refractory cases.

The efficacy and safety of pharmacological treatments for lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a rare, low-grade multisystem neoplastic disease. Most LAM patients are at a high risk of losing lung function at an accelerated rate and developing progressive dyspnea. Recently, several studies have reported their experience with pharmacological treatments for LAM. Therefore, we conducted a systematic review and meta-analysis to assess the efficacy and safety of these therapies.

METHODS

PubMed (Medline), EMBASE, Cochrane Library, Web of Science and EBSCO Host were searched (until March 31, 2019) for eligible prospective studies regarding LAM patients treated with pharmacological treatments. Random effect models were used for quantitative analysis.

RESULTS

Fourteen prospective studies regarding five pharmacological treatments (including sirolimus, everolimus, doxycycline, triptorelin, and a combination therapy of sirolimus and hydroxychloroquine) were enrolled in our systematic review, and ten of them were used for the meta-analysis. Seven prospective studies reported that sirolimus was effective at improving or stabilizing lung function and alleviating renal angiomyolipoma (AML) in LAM patients. Subsequent quantitative analyses showed that during sirolimus treatment, the pooled values of lung function and 6-min walk distance (6MWD) were not significantly changed (P > 0.05), with the pooled response rate of AML being 0.62 (95% confidence intervals [CIs]: 0.43 to 0.82, I2 = 65%). Regarding everolimus, three prospective studies reported similar effects to those of sirolimus with regard to preserving lung function and reducing AMLs. The meta-analysis showed that the changes in lung function during everolimus treatment were not statistically significant (P > 0.05), while the pooled response rate of AML was 0.78 (95% CI: 0.68 to 0.88, I2 = 8%). Neither the qualitative nor the quantitative results confirmed the benefits of doxycycline or triptorelin treatment, and the effects of the combination therapy were unclear in LAM patients. Most of the adverse events during pharmacological treatments were low or moderate grade and tolerable.

CONCLUSIONS

Overall, sirolimus and everolimus were recommended for the treatment of LAM because they could stabilize lung function and alleviate renal AML. Doxycycline and triptorelin were not recommended for the treatment of LAM because no beneficial outcomes were consistently observed. The efficacy and safety of combination therapy remain to be further explored.

Zoledronic acid inhibits TSC2-null cell tumor growth via RhoA/YAP signaling pathway in mouse models of lymphangioleiomyomatosis

Background

This study is to investigate the effects of zoledronic acid (ZA) on TSC2-null cell proliferation and on the tumor progression and recurrence in mouse models of lymphangioleiomyomatosis (LAM).

Methods

Subcutaneous mouse models and LAM mouse models were established. Immunohistochemistry and immunofluorescence were performed to detect the protein expression levels. TUNEL assay was conducted to detect cell apoptosis. Immunoprecipitation was carried out to determine the interaction between proteins.

Results

ZA prevented the growth of TSC2-null cells both in culture and in LAM mouse models. Compared with rapamycin, ZA more effectively promoted the apoptosis of TSC2-null cells. Moreover, combined with the rapamycin, ZA effectively suppressed the tumor recurrence after drug withdrawal and ZA inhibited the activity of GTPase RhoA by decreasing protein geranylgeranylation, resulting in changes of Yap nucleus translocation.

Conclusion

ZA promotes cell apoptosis in TSC2-null cells through the RhoA/YAP signaling pathway. ZA may be used for the clinical treatment of LAM.

Quantitative analysis of computed tomography of the lungs in patients with lymphangioleiomyomatosis treated with sirolimus

Objectives

We aimed to study sirolimus-related lung parenchymal changes by quantitative analysis of computed tomography (CT) of the lungs in patients with lymphangioleiomyomatosis (LAM).

Methods

We studied 20 participants from the Multicenter Lymphangioleiomyomatosis Sirolimus Trial for Safety study, who had undergone both thin-section CT scans and pulmonary function tests at baseline, 12, and 24 months. Quantitative CT parameters such as CT-derived total lung capacity, percentage of low attenuation area (LAA%), lung density histogram, fractal property of low attenuation area, and airway dimensions were analyzed, and correlations were conducted between the longitudinal change in each quantitative CT measurement and changes in pulmonary function were examined. Among 20 participants, pre-trial (n = 8) and post-trial (n = 16) CT data were also analyzed to deduce pathophysiologic implications of the serial changes in CT parameters during trial periods.

Results

FEV₁ significantly increased from baseline to 24 months (slope 3.71 ± 1.50 ml/month) whereas FVC didn't during sirolimus therapy. Strikingly, LAA%, and skewness and kurtosis of density histogram significantly increased from baseline to 24 months, while mean and mode CT values significantly decreased from baseline to 24 months. Statistically significant positive correlations were found between ΔFEV₁ and Δskewness (r = 0.465, p = 0.045). Taking the changes in lung density during pre-trial period into consideration, sirolimus decreases the area of -800 to -750 Housefield unit (HU) density and inhibits the decrease of -950 to -800 HU area during treatment, then producing the increased LAA% during the trial and post-trial periods. Given few sirolimus-related changes in airway dimensions, possible changes in lung mechanics may have contributed to increased FEV₁.

Conclusion

Our study suggests that the lung density histogram parameters, kurtosis, and skewness, may be useful as indicators of the efficacy of sirolimus.

Long-term efficacy and safety of sirolimus therapy in patients with lymphangioleiomyomatosis

BACKGROUND

Sirolimus has been confirmed to be effective for lymphangioleiomyomatosis (LAM), a rare multisystem neoplastic disease in women. The long-term effects of sirolimus treatment for LAM, however, are largely unknown. We aimed to analyze the long-term efficacy and safety of sirolimus therapy for LAM with 4-year follow-up.

METHODS

In total, 142 sporadic LAM patients who took sirolimus for 1-4 years were retrospectively enrolled for this analysis. The variables used for analysis included pulmonary function tests, arterial blood gas analysis, 6-min walking distance (6MWD), St. George's Respiratory Questionnaires (SGRQ) and serum vascular endothelial growth factor-D (VEGF-D) levels before and after the initiation of sirolimus therapy. The rates of change (slope) in those variables were calculated, and adverse events were also analyzed.

RESULTS

In total, 122, 83, 60 and 32 patients out of 142 were followed for 1, 2, 3 and 4 years respectively. Sirolimus treatment improved the change rate in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) compared with the data before treatment (FEV1, - 10 ± 15 vs. - 178 ± 36 ml/y, P <  0.001 and FVC, 54 ± 22 vs.-72 ± 68 ml/y, P < 0.05). In comparison to the baseline measurements, significant improvements were observed in FEV1 at the first year; FVC at 1-2 years; arterial oxygen levels, 6MWD, and SGRQ at 1-3 years; and VEGF-D at 1-4 years. Overall, all variables stabilized or improved during the 4 years of observation. Adverse events related to sirolimus were mild.

CONCLUSION

Sirolimus therapy is effective at improving or stabilizing pulmonary function, oxygen levels, exercise capacity, and quality of life in patients with LAM for up to 4 years. VEGF-D is maintained at a lower level for 4 years after treatment. Adverse events related to sirolimus were mild.

Angiotensin-converting enzyme inhibitors may affect pulmonary function in lymphangioleiomyomatosis

INTRODUCTION

A local renin-angiotensin system exists in the pulmonary nodules of lymphangioleiomyomatosis patients. Sirolimus, the standard treatment for lymphangioleiomyomatosis, stabilizes lung function, but all patients do not respond to or tolerate sirolimus. As renin-angiotensin systems may affect tumor growth and metastasis, we questioned if angiotensin-converting enzyme inhibitors affected lymphangioleiomyomatosis disease progression.

METHODS

Retrospective study of 426 patients was performed, examining angiotensin-converting enzyme levels, pulmonary function data, and angiotensin-converting enzyme inhibitor treatment.

RESULTS

Serum angiotensin-converting enzyme levels were elevated in approximately 33% of patients, increased with duration of disease, and were inversely correlated with pulmonary function. Levels decreased significantly over time with sirolimus treatment. Treatment with angiotensin-converting enzyme inhibitors was reported by approximately 15% of patients and was significantly associated with a slower rate of decline in percentage predicted forced expiratory volume (FEV1) and diffusing capacity of the lungs for carbon monoxide (DLCO) in patients not treated with sirolimus. No significant differences in rates of decline of FEV1 or DLCO were seen in patients treated with both inhibitors and sirolimus versus sirolimus alone.

CONCLUSIONS

Angiotensin-converting enzyme inhibitors may slow decline of pulmonary function in patients with lymphangioleiomyomatosis not treated with sirolimus. These inhibitors may be an option or adjunct in the treatment of lymphangioleiomyomatosis. A clinical trial may be warranted to examine this possibility.

FUNDING

NIH.

Successful Sirolimus Treatment of Lymphangioleiomyomatosis in a Hepatitis B Virus Carrier

A 34-year-old woman experiencing shortness of breath was referred to our hospital. The patient was diagnosed with sporadic lymphangioleiomyomatosis based on the observation of bilateral diffuse multiple thin-walled cysts on computed tomography of the chest, chylous effusion, elevated serum vascular endothelial growth factor-D levels and transbronchial biopsy findings. This patient was a hepatitis B virus (HBV) carrier. Treatment with 1 mg daily of sirolimus was started after HBV DNA was brought below the cut-off level using entecavir. Sirolimus was effective, as the chylous effusion resolved completely and the dyspnea improved. The sirolimus dosage was increased to 2 mg daily without causing HBV reactivation.

Use of CT Imaging to Quantify Progression and Response to Treatment in Lymphangioleiomyomatosis

BACKGROUND

In lymphangioleiomyomatosis (LAM), infiltration of the lungs with smooth muscle-like LAM cells results in cystic destruction and decline in lung function, effects stabilized by sirolimus therapy. LAM lung disease is followed, in part, by high-resolution CT scans. To obtain further information from these scans, we quantified changes in lung parenchyma by analyzing image "texture."

METHODS

Twenty-six texture properties were quantified by analyzing the distribution and intensity of pixels with a computer-aided system. Both cross-sectional and longitudinal studies were performed to examine the relationships between texture properties, cyst score (percentage of lung occupied by cysts), FEV₁, and diffusion capacity for carbon monoxide (Dlco), and to determine the effect of sirolimus treatment.

RESULTS

In the cross-sectional study, 18 texture properties showed significant positive correlations with cyst score. Cyst score and 13 of the 18 texture properties showed significant differences in rates of change after sirolimus treatment; 11 also significantly predicted FEV₁ and Dlco.

CONCLUSIONS

Increased cyst score was associated with increased texture degradation near cysts. Sirolimus treatment improved lung texture surrounding cysts and stabilized cyst score. Eleven texture properties were associated with FEV₁, Dlco, cyst score, and response to sirolimus. Texture analysis may be valuable in evaluating LAM severity and treatment response.

Low-dose sirolimus in retroperitoneal lymphangioleiomyomas

Lymphangioleiomyomatosis (LAM) is a rare disease associated with cystic lung destruction and abdominal tumors, including lymphangioleiomyomas, which frequently occur in the retroperitoneal region. Sirolimus therapy is currently recommended for LAM patients with abnormal or declining lung function with an adjusted dose to maintain a serum trough level of 5–15 ng/mL. We describe a significant reduction of retroperitoneal lymphangioleiomyomas after treatment with low-dose sirolimus therapy (serum trough level <5 ng/mL) in a patient with sporadic LAM.

Efficacy and safety of low-dose Sirolimus in Lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis is a rare disease caused by unregulated activation of mammalian target of rapamycin (mTOR) signalling pathway. Sirolimus showed efficacy in a phase 3 trial of patients with lymphangioleiomyomatosis, but the optimal dose remains unclear.

METHODS

We investigated the efficacy and safety of low-dose compared with conventional-dose sirolimus. Clinical data of 39 patients with lymphangioleiomyomatosis (mean age, 34.8 years; median treatment period, 29.6 months) who received sirolimus were retrospectively reviewed. Low-dose sirolimus was defined as any dose that maintained mean blood trough levels lower than those maintained with conventional doses (5-15 ng/mL).

RESULTS

Fifty-one percent of patients received low-dose therapy. The rate of decline in lung function decreased after treatment in the whole group (forced expiratory volume in 1 s [FEV₁], - 0.12 ± 0.47 [before] vs. 0.24 ± 0.48% predicted/month [after], p = 0.027; diffusing capacity for carbon monoxide [DLco], - 0.33 ± 0.61 vs. 0.03 ± 0.26% predicted/month, p = 0.006) compared with before treatment. In the low-dose group, the rate of decline in FEV₁ (- 0.08 ± 0.38 [before] vs. 0.19 ± 0.51% predicted/month [after], p = 0.264) and DLco (-0.13 ± 0.62 vs. 0.02 ± 0.28% predicted/month, p = 0.679) showed a numeric trend towards improvement after treatment; however, the conventional-dose group showed significant improvement in FEV₁ (- 0.26 ± 0.54 [before] vs. 0.22 ± 0.38 [after] % predicted/month, p = 0.024) and DLco (- 0.55 ± 0.58 vs. 0.04 ± 0.25% predicted/month, p = 0.002) after treatment. Adverse events (AEs) occurred in 89.7% of patients and the most common AEs was hypercholesterolaemia (43.6%), followed by stomatitis (35.9%). The occurrences of AE were similar between the low- and conventional-dose groups (85.0% vs. 94.7%, p = 0.605).

CONCLUSIONS

Low-dose sirolimus may stabilise lung function decline in lymphangioleiomyomatosis patients, but its efficacy appears to be inferior to that of conventional-dose sirolimus.

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.