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%.

[Diffuse cystic lung disease]. / Cystische Lungenerkrankungen.

INTRODUCTION: Diffuse cystic lung disease (DCLD) represents a heterogeneous group of conditions, typically characterized by the presence of multiple thin-walled, predominantly round parenchymal lucencies. The increased accessibility of computed tomography (CT) underscores the growing relevance of a relatively rare group of diseases as more clinicians are confronted with the presence of multiple lung cysts on the chest CT scan. Although the etiology of these conditions is very diverse, the focus of the differential diagnosis revolves around four primary causative factors - Lymphangioleiomyomatosis (LAM), Pulmonary Langerhanscell histiocytosis (PLCH), Birt-Hogg-Dubé (BHD) and lymphoid interstitial pneumonia (LIP). Achieving an accurate diagnosis poses a challenge and typically necessitates lung biopsies; however, it is crucial for ensuring proper management.

Lymphangioleiomyomatosis in patients with tuberous sclerosis: a national centre audit.

BACKGROUND: Lymphangioleiomyomatosis (LAM) is common in tuberous sclerosis complex (TSC) yet under recognised with management mostly based upon evidence obtained from patients with sporadic LAM. We performed a prospective audit of patients with TSC-LAM attending a national referral centre to inform management guidelines. METHODS: The UK LAM Centre was established in 2011 and conducts a prospective audit of pre-defined quality outcomes for all subjects. Audit data are reported on all patients with TSC-LAM and a comparator population of patients with sporadic LAM. RESULTS: Between 2011 and 2022, 73 patients were seen with TSC-LAM. All were women with a mean (SD) age of 39 (12) years. Referral rates were similar over the study period including after the introduction of CT screening. Median age of diagnosis with TSC was 11 years (range 0-70) with one third diagnosed with TSC as adults. Compared with all TSC patients in the 'TOSCA' registry, TSC-LAM patients tended to have been diagnosed with TSC at an older age, had fewer neuro-cognitive manifestations and were more likely to have angiomyolipoma. The most common presentations of TSC-LAM were following workup for angiomyolipoma, pneumothorax or dyspnoea with only one fifth detected after CT screening. Baseline FEV1 and DLCO at first assessment were reduced to 77 and 63% predicted respectively and were similar to patients with sporadic LAM. During follow-up, FEV1 fell by a mean of 81 ml/year and DLCO fell by 0.309 mmol/ml/kPa/year in patients not being treated with an mTOR inhibitor. 55% required treatment with either sirolimus or Everolimus for LAM or angiomyolipoma respectively. For those treated with an mTOR inhibitor, mean FEV1 fell by 3 ml/year and DLCO increased by 0.032 mmol/ml/kPa/year and was similar to sporadic LAM. Risk of death due to LAM or need for lung transplant in patients with TSC-LAM was 0.67%/year. CONCLUSIONS: Despite screening recommendations, LAM is often diagnosed in TSC after symptoms develop which may delay treatment. Complications including pneumothorax and loss of lung function are significant and similar to sporadic LAM. Work is needed to implement the recommended CT screening for LAM and improve respiratory care for TSC-LAM.

An elderly woman with Birt-Hogg-Dubé syndrome having multiple pulmonary cysts mimicking lymphangioleiomyomatosis.

The characteristics of the pulmonary cysts on the high-resolution computed tomography (HRCT) chest images are an important diagnostic clue to distinguish among cystic lung diseases. The diagnostic accuracy of HRCT was reported to be as high as 90% by experienced pulmonologists and radiologists. Herein, we report the case of an elderly woman with Birt-Hogg-Dubé syndrome (BHDS) whose HRCT images displayed lymphangioleiomyomatosis-like features of the pulmonary cysts, rendering it difficult for us to diagnose BHDS. This case illustrates the significance of a thorough anamnesis, physical examination, and skin biopsy of facial papules to establish an accurate diganosis.

Intraoperative mechanical ventilation and incidence of pneumothorax in lymphangioleiomyomatosis.

Patients with lymphangioleiomyomatosis (LAM) are considered high risk for most surgeries and require specific anesthetic considerations mainly because of the common spontaneous pneumothorax (PTX). To explore whether intraoperative mechanical ventilation could increase the risk of PTX in those patients, we included 12 surgical patients with LAM in this study, of whom four (33.3%) experienced postoperative PTX. According to our results, patients with higher CT grade, poorer pulmonary function, and a history of preoperative PTX might be more likely to develop postoperative PTX. However, intraoperative mechanical ventilation did not show obvious influence, which might help clinicians reconsider the perioperative management of LAM patients.

Healthcare provider recognition of pregnancy related risks and management considerations in patients with tuberous sclerosis complex.

BACKGROUND: Patients with tuberous sclerosis complex (TSC) face an increased risk of maternal health complications and worsening disease manifestations during pregnancy. There are no established consensus guidelines that address the management of pregnancy in patients with TSC and healthcare providers rely on their individual experiences and preferences to derive treatment decisions. We sought to obtain provider opinion of pregnancy related maternal complications in patients with TSC, and the common evaluation and management strategies used to address these issues. METHODS: We conducted a cross-sectional survey of healthcare providers with diverse areas of expertise related to the multisystem nature of involvement in TSC. Descriptive analyses were used to analyze our three primary variables: (1) provider recognition of maternal risks/complications; (2) provider recommendations before and during pregnancy; and (3) provider/clinic protocols. RESULTS: We received responses from 87 providers from 11 countries, with 40.7% (n = 35) seeing > 30 TSC patients yearly. The majority of providers (n = 70, 88.6%) deemed that a patient with TSC needed expert care beyond the standard of care for a typical pregnancy, with over 25% of providers reporting that they have seen lymphangioleiomyomatosis (LAM) exacerbation, seizures, and preterm labor in pregnant patients with TSC. Providers who managed patients treated with mTOR inhibitors (mTORi) also agreed that mTORi use should be stopped prior to pregnancy (n = 45, 68.2%) but there was uncertainty about when to stop the mTORi (one month 28.9%, two months 11.1%, three months 42.2%, and 6-12 months 2.2%). Additionally, there were mixed opinions on restarting mTORi in response to disease progression during pregnancy. When asked about provider or clinic specific protocols, 71.6% (n = 53) of providers stated that they do not have a clear protocol for management decisions for patients with TSC before or during pregnancy. CONCLUSION: Healthcare providers recognize that patients with TSC are at an increased risk for maternal health complications during pregnancy. However, there are wide inter-individual variances in practice, especially pertaining to decisions regarding mTORi use. There is a critical need to better understand the implications of pregnancy for patients with TSC, and to draft consensus recommendations to guide management decisions.

Small airways morphological alterations associated with functional impairment in lymphangioleiomyomatosis.

BACKGROUND: Lymphangioleiomyomatosis (LAM) is a rare neoplastic and cystic pulmonary disease characterized by abnormal proliferation of the so-called LAM cells. Despite the functional obstructive pattern observed in most patients, few studies investigated the morphological changes in the small airways, most of them in patients with severe and advanced LAM undergoing lung transplantation. Understanding the morphological changes in the airways that may occur early in the disease can help us understand the pathophysiology of disease progression and understand the rationale for possible therapeutic approaches, such as the use of bronchodilators. Our study aimed to characterize the morphological alterations of the small airways in patients with LAM with different severities compared to controls, and their association with variables at the pulmonary function test and with LAM Histological Score (LHS). METHODS: Thirty-nine women with LAM who had undergone open lung biopsy or lung transplantation, and nine controls were evaluated. The histological severity of the disease was assessed as LHS, based on the percentage of tissue involvement by cysts and infiltration by LAM cells. The following morphometric parameters were obtained: airway thickness, airway closure index, collagen and airway smooth muscle content, airway epithelial TGF-ß expression, and infiltration of LAM cells and inflammatory cells within the small airway walls. RESULTS: The age of patients with LAM was 39 ± 8 years, with FEV1 and DLCO of 62 ± 30% predicted and 62 ± 32% predicted, respectively. Patients with LAM had increased small airway closure index, collagen and smooth muscle content, and epithelial TGF-beta expression compared with controls. Patients with LAM with the more severe LHS and with greater functional severity (FEV1 ≤ 30%) presented higher thicknesses of the airways. Bronchiolar inflammation was mild; infiltration of the small airway walls by LAM cells was rare. LHS was associated with an obstructive pattern, air trapping, and reduced DLCO, whereas small airway wall thickness was associated with FEV1, FVC, and collagen content. CONCLUSION: LAM is associated with small airway remodelling and partial airway closure, with structural alterations observed at different airway compartments. Functional impairment in LAM is associated with airway remodelling and, most importantly, with histological severity (LHS).

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]. / Maladies kystiques pulmonaires de l'adulte d'origine génétique.

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.

Safety and efficacy of cryobiopsy for the diagnosis of lymphangioleiomyomatosis compared with forceps biopsy and surgical lung biopsy.

BACKGROUND: Transbronchial lung forceps biopsy (TBFB) is recommended before a surgical lung biopsy (SLB) when a definitive diagnosis of lymphangioleiomyomatosis (LAM) is required for patients without any additional confirmatory features. Transbronchial lung cryobiopsy (TBCB) has been suggested as replacement test in patients considered eligible to undergo SLB for the diagnosis of interstitial lung diseases. The efficacy and safety of TBCB were compared with that of TBFB and SLB in the diagnosis of LAM. METHODS: A retrospective analysis was conducted on 207 consecutive patients suspected with LAM in the First Affiliated Hospital of Guangzhou Medical University from 2005 to 2020. RESULTS: The difference in diagnostic rate of patients suspected with LAM between TBCB (20/30, 66.7%) and TBFB (70/106, 66.0%) groups was not significant (p = 0.949). One patient performed TBCB with negative pathological results could be diagnosed exclusively after SLB. LAM diagnosis was confirmed by surgical pathological findings in 3 TBFB-negative patients. More patients with minimal cystic profusion were diagnosed with LAM by TBCB (5/19, 26.3%) and SLB (11/39, 28.2%) than by TBFB (3/61, 4.9%) (TBCB vs TBFB: p = 0.04, SLB vs TBFB, p < 0.001). The difference between the severity of cystic lung disease in patients diagnosed with LAM through TBCB and SLB was not significant (p > 0.05). One pneumothorax, 8 mild bleeding and 1 moderate bleeding were observed in TBCB. One pneumothorax, 15 mild bleeding and 1 moderate bleeding occurred after TBFB. CONCLUSION: Compared to TBFB, TBCB is safe and effective in diagnosing LAM at a higher diagnostic rate in patients with minimal cystic profusion.

Sporadic Lymphangioleiomyomatosis Disease: A Case Report.

Pulmonary Lymphangioleiomyomatosis (LAM) is a rare disease of the lung and lymphatic system that primarily affects women of childbearing age. LAM is a progressive disease with a terrible prognosis, which worsens over time and is extremely difficult to treat. In this study, we discuss the case of a 31-year-old woman with LAM who was initially misdiagnosed with leiomyoma and the way that led to a true diagnosis and effective treatment. Following a precise diagnosis based on comprehensive clinical data and particular immunohistochemical tests, sirolimus treatment was initiated, and the patient entirely responded to the treatment. This case report demonstrated that LAM is an uncommon condition that is challenging to diagnose, which causes its treatment to be delayed.

Lost in translation: a neglected mTOR target for lymphangioleiomyomatosis.

Lymphangioleiomyomatosis (LAM) is a cystic lung disease of women resulting from mutations in tuberous sclerosis complex (TSC) genes that suppress the mammalian target of rapamycin complex 1 (mTORC1) pathway. mTORC1 activation enhances a plethora of anabolic cellular functions, mainly via the activation of mRNA translation through stimulation of ribosomal protein S6 kinase (S6K1)/ribosomal protein S6 (S6) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1)/eukaryotic translation initiation factor 4E (eIF4E). Rapamycin (sirolimus), an allosteric inhibitor of mTORC1, stabilises lung function in many but not all LAM patients and, upon cessation of the drug, disease progression resumes. At clinically tolerable concentrations, rapamycin potently inhibits the ribosomal S6K1/S6 translation ribosome biogenesis and elongation axis, but not the translation 4E-BP1/eIF4E initiation axis. In this mini-review, we propose that inhibition of mTORC1-driven translation initiation is an obvious but underappreciated therapeutic strategy in LAM, TSC and other mTORC1-driven diseases.