Pulmonary manifestations in tuberous sclerosis complex

Insights into Tuberous Sclerosis Complex : From Genes to Clinics

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder caused by pathogenic variants of TSC1 or TSC2 genes, leading to dysregulation of the mammalian target of rapamycin (mTOR) pathway. This dysregulation results in the formation of organ-specific tumors and neurological manifestations such as seizures, intellectual disability, and developmental delays. These characteristic clinical features are crucial for diagnosis, and genetic testing is playing an increasingly significant role. Long-term disease monitoring and appropriate interventions by multidisciplinary experts, including the use of mTOR inhibitors and promising therapeutic agents based on disease pathomechanisms, are essential for effective TSC management and improved clinical outcomes.

Pediatric reference values of VEGF-D derived from a German population-based cohort of healthy children

BACKGROUND

Vascular endothelial growth factor D (VEGF-D) is a growth-factor involved in the development of blood vessels and lymphatics in tissues all over the human body. Interestingly, VEGF-D serum levels are increased in certain tumor entities. For tuberous sclerosis complex (TSC), a rare genetic disease associated with (benign) tumor growth, VEGF-D is already implemented as a diagnostic and therapeutic biomarker to monitor onset and progress of lymphangioleiomyomatosis (LAM), one of the noncancerous tumor manifestations in mainly female adult TSC patients. To date only adult VEGF-D serum cut off values are established and used as a diagnostic tool in LAM. Neither cut off nor pediatric reference values for VEGF-D serum levels are known, our study aims to provide reliable pediatric VEGF-D results in samples from healthy children and adolescents.

METHODS

We analyzed 2003 samples provided by healthy children aged 0.25-18 years participating in the prospective longitudinal population-based cohort study "LIFE Child" in Leipzig, Germany. Serum VEGF-D levels were measured by enzyme-linked immunoassay.

RESULTS

VEGF-D levels in healthy children and adolescents show age-and gender specific variations. We showed a significant difference between girls and boys in post pubertal VEGF-D levels. Especially the fact, that girls showed higher VEGF-D levels with advancing stages of puberty is underlining the importance of estrogen metabolism in context of VEGF-D mediated cell proliferation, angiogenesis and associated disease mechanisms.

CONCLUSION

Knowing VEGF-D levels in growing healthy young children and adolescents could help to recognize early disease progression of LAM in individuals at risk especially young women suffering from TSC. Further studies are needed on VEGF-D serum levels in children, especially the impact of estrogen metabolism on VEGF-D should be investigated further.

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.

Rare genetic interstitial lung diseases: a pictorial essay

The main monogenic causes of pulmonary fibrosis in adults are mutations in telomere-related genes. These mutations may be associated with extrapulmonary signs (hepatic, haematological and dermatological) and typically present radiologically as usual interstitial pneumonia or unclassifiable fibrosis. In children, the monogenic causes of pulmonary fibrosis are dominated by mutations in surfactant-related genes. These mutations are not associated with extrapulmonary signs and often manifest radiologically as unclassifiable fibrosis with cysts that can lead to chest wall deformities in adults. This review discusses these mutations, along with most of the monogenic causes of interstitial lung disease, including interferon-related genes, mutations in genes causing cystic lung disease, Hermansky-Pudlak syndrome, pulmonary alveolar proteinosis, lysinuric protein intolerance and lysosomal storage disorders, and their pulmonary and extrapulmonary manifestations.

Clinical, tomographic and functional comparison of sporadic and tuberous sclerosis complex-associated forms of lymphangioleiomyomatosis: a retrospective cohort study

Background

Lymphangioleiomyomatosis (LAM) is a rare disease that can occur sporadically (S-LAM) or associated with the tuberous sclerosis complex (TSC-LAM). The natural history of LAM is not completely understood, including whether there is a difference between the clinical courses of the two forms. This study aimed to compare the clinical, functional and tomographic features between S-LAM and TSC-LAM, and evaluate the annual rates of change in lung function.

Methods

This retrospective cohort study included patients with LAM followed up between 1994 and 2019. Clinical, functional and imaging variables were evaluated, and the lung cysts were automatically quantified. Quality of life and predictors of lung function impairment were accessed, and the annual rate of lung function decline was compared between S-LAM and TSC-LAM.

Results

Of the 107 patients included, 77 had S-LAM and 30 had TSC-LAM. Although patients with TSC-LAM had a higher prevalence of renal angiomyolipomas and neurological and dermatological manifestations, pulmonary function tests were similar. Patients with S-LAM had a greater rate of forced expiratory volume in 1 s decline and a higher extent of cysts. Pneumothorax, desaturation in the 6-minute walking test and a higher extent of lung cysts were predictors of functional impairment. A greater impact on vitality and emotional health was observed in the TSC-LAM.

Conclusion

Greater functional decline and a higher cystic extension were found in patients with S-LAM. Our study provides a broad clinical, functional and tomographic characterisation of patients with LAM, adding valuable information to the existing evidence to better understand the two forms of the disease.

Pathology of hereditary renal cell carcinoma syndromes: Tuberous sclerosis complex (TSC)

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disease characterized by hamartomatous tumors involving multiple organs such as the brain, skin, heart, lung and kidney. TSC is caused by inactivating mutations in TSC1/TSC2, which encodes hamartin and tuberin, respectively, and forms a complex that regulates mechanistic target of rapamycin complex 1 (mTORC1), resulting in cell overgrowth and oncogenesis. Since a leading cause of morbidity and mortality in TSC relates to chronic kidney disease and the ability to preserve renal function, this review describes the important pathologic findings in TSC-associated renal neoplasms and their correlating sporadic counterparts. The most common renal tumor in TSC patients are AMLs, followed by a heterogeneous spectrum of renal epithelial tumors, which may provide clues to establishing a diagnosis of TSC.

Neurocutaneous Disorders in Pregnancy

Importance

Neurocutaneous disorders have significant implications for care of the pregnant patient. As neurocutaneous disorders are uncommon, obstetricians may be unfamiliar with these disorders and with recommendations for appropriate care of this population.

Objective

This review aims to summarize existing literature on the interaction between neurocutaneous disorders and pregnancy and to provide a guide for physicians caring for an affected patient.

Evidence Acquisition

A PubMed, MEDLINE, and Google Scholar search was carried out with a broad range of combinations of the medical subject headings (MeSH) terms "pregnancy," "Sturge -Weber," "Neurofibromatosis Type 1," "neurofibromatosis type 2," "von Hippel Lindau," "Tuberous Sclerosis," "neurocutaneous disorder," "treatment," "congenital malformations," "neurodevelopmental defects," "miscarriage," "breastfeeding," "autoimmune," "pathophysiology," and "management." References of included articles were searched to identify any articles that may have been missed after the above method was used.

Results

Neurocutaneous disorders are associated with increased pregnancy-associated maternal and fetal/neonatal morbidity, largely surrounding hypertensive disorders, epilepsy, and medication exposure. Some features of neurocutaneous disorders may be worsened or accelerated by pregnancy. Neurocutaneous disorders can often be diagnosed prenatally. Therefore, directed assessment should be offered to affected individuals with a personal or family history of a neurocutaneous disorder.

Conclusion and Relevance

Patients affected by neurocutaneous disorders who are pregnant or planning for future pregnancy should be carefully followed by a multidisciplinary team, which could include maternal-fetal medicine, neurology, and anesthesia, as well as other relevant subspecialists. Additional research is required regarding optimal counseling and management of these patients.

Paradigm shift in the treatment of tuberous sclerosis: Effectiveness of everolimus

Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterised by abnormal cell proliferation and differentiation that affects multiple organs and can lead to the growth of hamartomas. Tuberous sclerosis complex is caused by the disinhibition of the protein mTOR (mammalian target of rapamycin). In the past, various therapeutic approaches, even if only symptomatic, have been attempted to improve the clinical effects of this disease. While all of these therapeutic strategies are useful and are still used and indicated, they are symptomatic therapies based on the individual symptoms of the disease and therefore not fully effective in modifying long-term outcomes. A new therapeutic approach is the introduction of allosteric inhibitors of mTORC1, which allow restoration of metabolic homeostasis in mutant cells, potentially eliminating most of the clinical manifestations associated with Tuberous sclerosis complex. Everolimus, a mammalian target of the rapamycin inhibitor, is able to reduce hamartomas, correcting the specific molecular defect that causes Tuberous sclerosis complex. In this review, we report the findings from the literature on the use of everolimus as an effective and safe drug in the treatment of TSC manifestations affecting various organs, from the central nervous system to the heart.

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.

Multiple Micronodular Pneumocyte Hyperplasia (MMPH): A Less-Known Presentation of Tuberous Sclerosis Complex Related Lung Disease

Teaching Point: Multiple micronodular pneumocyte hyperplasia (MMPH) is a less-known presentation of tuberous sclerosis complex (TSC) associated lung disease that usually requires no treatment or follow-up imaging.

Targeting SPHK1/S1PR3-regulated S-1-P metabolic disorder triggers autophagic cell death in pulmonary lymphangiomyomatosis (LAM)

Lymphangioleiomyomatosis (LAM), a progressive pulmonary disease exclusively affecting females, is caused by defects or mutations in the coding gene tuberous sclerosis complex 1 (TSC1) or TSC2, causing the mammalian target of rapamycin complex 1 (mTORC1) activation and autophagy inhibition. Clinically, rapamycin shows limited cytocidal effects, and LAM recurs after drug withdrawal. In this study, we demonstrated that TSC2 negatively regulated the sphingolipid metabolism pathway and the expressions of sphingosine kinase 1 (SPHK1) and sphingosine-1-phosphate receptor 3 (S1PR3) were significantly elevated in LAM patient-derived TSC2-deficient cells compared to TSC2-addback cells, insensitive to rapamycin treatment and estrogen stimulation. Knockdown of SPHK1 showed reduced viability, migration and invasion in TSC2-deficient cells. Selective SPHK1 antagonist PF543 potently suppressed the viability of TSC2-deficient cells and induced autophagy-mediated cell death. Meanwhile, the cognate receptor S1PR3 was identified to mediating the tumorigenic effects of sphingosine-1-phosphate (S1P). Treatment with TY52156, a selective antagonist for S1PR3, or genetic silencing using S1PR3-siRNA suppressed the viability of TSC2-deficient cells. Both SPHK1 and S1PR3 inhibitors markedly exhibited antitumor effect in a xenograft model of TSC2-null cells, restored autophagy level, and triggered cell death. Together, we identified novel rapamycin-insensitive sphingosine metabolic signatures in TSC2-null LAM cells. Therapeutic targeting of aberrant SPHK1/S1P/S1PR3 signaling may have potent therapeutic benefit for patients with TSC/LAM or other hyperactive mTOR neoplasms with autophagy inhibition.

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.

Construction of TSC2 knockout cell line using CRISPR/Cas9 system and demonstration of its effects on NIH-3T3 cells

Tuberous sclerosis complex (TSC) is a rare autosomal dominant disorder involving multiple organ systems. TSC2 gene plays an important role in the development of TSC. The most common kidney manifestation of TSC is renal angiomyolipoma (RAML). TSC-RAML is more likely to be bilateral multiple tumors and tends to destroy the renal structure and damages renal function severely. As a result, patients with TSC-RAML often miss the opportunity for surgical treatment when TSC-RAML is diagnosed, causing difficulty in obtaining tumor specimens through surgery. Due to this difficulty, model cell lines must be constructed for scientific research. In this paper, TSC2 was knocked out in NIH-3T3 cell lines by CRISPR/Cas9 system. PCR, WB and mTOR inhibitor drug sensitivity test showed that the TSC2 knockout NIH-3T3 cells were successfully constructed. The ability of proliferation and invasion in TSC2 KO NIH-3T3 cells were higher than those in wild type group. The constructed KO cell line lay the foundation for further study of TSC.

Tuberous sclerosis complex with skin lesions as the initial presentation: A case report and multidisciplinary discussion

We reported a case of tuberous sclerosis complex with facial angiofibroma as the initial presentation and conducted a multidisciplinary discussion. The patient, a young female, was admitted to the Department of Dermatology for cosmetic purpose. After the examination, she was found to have multiple system involvement, including a large renal angiomyolipoma pressing on the liver. She never had any subjective symptom. After consultation by the multidisciplinary team of tuberous sclerosis complex, the patient was treated with everolimus orally and followed up regularly. It is suggested that dermatologists should pay attention to the systemic involvement of patients with tuberous sclerosis complex. Early intervention can prolong the life of patients and improve their life quality. Multidisciplinary collaboration for lifelong disease management is the key to enhance the diagnosis and treatment for tuberous sclerosis complex and enhance the prognosis of patients.

Monitoring and Managing Patients with Tuberous Sclerosis Complex: Current State of Knowledge

Tuberous sclerosis complex (TSC) is a rare genetic disease of autosomal dominant transmission that, in most cases, results from the presence of pathogenic variants of the TSC1 or TSC2 genes, encoding hamartin and tuberin, respectively. It is a multisystemic disease, affecting most frequently the brain, skin, kidney, and heart. The wide variety of possible clinical manifestations, given this multisystem dimension, makes the follow-up of patients with TSC an exercise of multidisciplinarity. In fact, these patients may require the intervention of various medical specialties, which thus have to combine their efforts to practice a medicine that is truly holistic. The past few years have witnessed a dramatic leap not only in the diagnosis and management of TSC patients, with standard monitoring recommendations, but also in the therapeutic field, with the use of mTORC1 inhibitors. In this article, we review the clinical manifestations associated with TSC, as well as the treatment and follow-up strategies that should be implemented, from a multidisciplinary perspective.

Analysis of Clinical Features and Next-Generation Sequencing of 12 Tuberous Sclerosis Families in China

Background

Tuberous sclerosis complex (TSC) is a rare autosomal dominant genetic disease with systemic organ involvement. So far, only a few TSC families in China have been reported. Therefore, more data on the clinical and genetic features of TSC families are required.

Materials and Methods

We retrospectively analyzed 12 TSC family probands and their family members. Next-generation sequencing (NGS) has been applied to confirm the type of TSC mutation along with a detailed physical examination.

Results

In this study, twenty-seven patients in 12 TSC families were reported, including 12 male and 15 female patients, aged 8-67 years. Skin lesions were detected among all patients with TSC, including 25 cases of facial angiofibromas, 18 cases of hypomelanotic macules, 15 cases of ungual fibromas, and 13 cases of shagreen patch. Other clinical features were also revealed: 14 cases of renal angiomyolipoma, 6 cases of subependymal nodules (SENs), and 3 cases of lymphangioleiomyomatosis. All twenty-seven patients with TSC were tested by NGS. Totally, TSC2 mutations were reported in 19 cases (7 frameshift mutations, 10 nonsense mutations, and 2 missense mutations), TSC1 mutations were reported in 4 cases (4 nonsense mutations), and 4 cases were genetically negative. The novel causal mutations (TSC2: c.208dup, c.1874C > G, c.1852del) identified in three families were first reported in TSC.

Conclusion

Our findings expand the mutation spectrum of patients with TSC in China. The clinical characteristics can vary among patients with TSC with the same pathogenic mutation. The genetic results and summary of clinical features of 12 TSC families contribute to a more accurate diagnosis and further genetic counseling.

Tuberous sclerosis complex: a complex case

Tuberous sclerosis complex (TSC) is an inheritable disorder characterized by the formation of benign yet disorganized tumors in multiple organ systems. Germline mutations in the TSC1 (hamartin) or more frequently TSC2 (tuberin) genes are causative for TSC. The malignant manifestations of TSC, pulmonary lymphangioleiomyomatosis (LAM) and renal angiomyolipoma (AML), may also occur as independent sporadic perivascular epithelial cell tumor (PEComa) characterized by somatic TSC2 mutations. Thus, discerning TSC from the copresentation of sporadic LAM and sporadic AML may be obscured in TSC patients lacking additional features. In this report, we present a case study on a single patient initially reported to have sporadic LAM and a mucinous duodenal adenocarcinoma deficient in DNA mismatch repair proteins. Moreover, the patient had a history of Wilms' tumor, which was reclassified as AML following the LAM diagnosis. Therefore, we investigated the origins and relatedness of these tumors. Using germline whole-genome sequencing, we identified a premature truncation in one of the patient's TSC2 alleles. Using immunohistochemistry, loss of tuberin expression was observed in AML and LAM tissue. However, no evidence of a somatic loss of heterozygosity or DNA methylation epimutations was observed at the TSC2 locus, suggesting alternate mechanisms may contribute to loss of the tumor suppressor protein. In the mucinous duodenal adenocarcinoma, no causative mutations were found in the DNA mismatch repair genes MLH1, MSH2, MSH6, or PMS2 Rather, clonal deconvolution analyses were used to identify mutations contributing to pathogenesis. This report highlights both the utility of using multiple sequencing techniques and the complexity of interpreting the data in a clinical context.

Multifocal micronodular pneumocyte hyperplasia lacking typical clinical features of the tuberous sclerosis complex: a case report and literature review

Background

Multifocal micronodular pneumocyte hyperplasia (MMPH) is a rare pulmonary manifestation of the tuberous sclerosis complex (TSC) with distinctive histological characteristics. Most case reports of MMPH associated with TSC usually have a history and typical clinical features (seizures, mental retardation, and skin lesions) of TSC. We present a peculiar asymptomatic MMPH case that lacked the history and typical clinical features of TSC.

Case presentation

A 56-year-old man was referred to our hospital with bilateral ground-glass opacities (GGOs) on chest computed tomography (CT) lasting 8 months, with no complaint of any discomfort. Because of the lack of clinical manifestations, the diagnosis of MMPH and TSC was confirmed by lung biopsy histopathology and gene sequencing of nonsense mutations in the TSC1 gene. Considering the relevant literature review and that the prognosis of most patients with MMPH is generally stable, no special treatment was given. We followed up with the patient for three years after discharge, and the clinical manifestations and imaging features of the patient were stable.

Conclusion

To our best knowledge, this is the first case of MMPH lacking typical clinical manifestations of TSC confirmed by histopathology combined with gene sequencing. MMPH should be considered as one of the differential diagnoses of multiple GGOs in the lung even when the findings of TSC are not recognized.

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.

Recurrent pneumothoraces with diffuse small ground-glass and solid nodules

Multifocal micronodular pneumocyte hyperplasia (MMPH) is the lesser known pulmonary manifestation of tuberous sclerosis. It manifests radiologically as diffuse small ground-glass and solid nodules. Accurate diagnosis is essential as it can be mistaken for miliary tuberculosis or malignant lesions which necessitates specific treatment. Constellation of radiological features such as multicentric disease at onset and stability over time can help to distinguish MMPH from its differentials. Histologically, MMPH is characterized by hamartomatous proliferation of type II pneumocytes with a lack of high nuclear to cytoplasmic ratio. MMPH confers a benign prognosis unlike its differentials. Therefore, accurate diagnosis is paramount in ensuring appropriate care is delivered. Here, we describe the radiological and histological features of MMPH in a patient with genetically proven tuberous sclerosis complex and co-existing lymphangioleiomyomatosis.

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.

18F-FDG Positron Emission Tomography/Computed Tomography (PET/CT) for Distinguishing Tuberous Sclerosis Complex Lesions from Colon Cancer Metastases

Patient: Female, 17-year-old

Final Diagnosis: Tuberous sclerosis complex

Symptoms: No specific symptoms

Medication:—

Clinical Procedure: —

Specialty: Nuclear Medicine

Incidental case finding of a 19-year-old woman with Tuberous Sclerosis Complex: A step-wise Multidisciplinary approach

Radiological imaging plays a vital role in clinically diagnosing TSC. TSC prognosis is largely determined by the severity and the extent of the systems affected by it. TSC patients are symptomatically managed, since no cure is present. Healthcare professionals must frequently check-up TSC patients who have a lifelong disorder.

Lymphangioleiomyomatosis Association with Underlying Genotype in Patients with Tuberous Sclerosis Complex

Rationale: Lymphangioleiomyomatosis (LAM) is a female-predominant lung disease caused by mutations in the tuberous sclerosis complex (TSC) genes TSC1 and TSC2.Objectives: To examine the association between TSC mutation subtypes and the prevalence of LAM in women with TSC.Methods: Adult women seen at the Cincinnati Children's Hospital Medical Center's TSC clinic were stratified into the following three groups: those with TSC1 mutation, those with TSC2 mutation, and those with no mutation identified (NMI). Individual TSC manifestations were ascertained by blinded review of chest computed tomographic scans (LAM, multifocal micronodular pneumocyte hyperplasia, and sclerotic bone lesions) and chart review (all other manifestations). The association between mutation status and TSC manifestations was assessed by the Wilcoxon rank-sum test.Results: Our cohort consisted of 55 TSC women, including 30/55 (55%) with TSC2, 12/55 (22%) with TSC1, and 13/55 (23%) with NMI. Twenty-three women (42%) had characteristic cysts consistent with LAM, of whom 16 had TSC2 mutations and seven had NMI. The prevalence of LAM was higher in women with TSC2 mutations compared with women with TSC1 mutations (16/29 [55%] vs. 0/12; P = 0.003). Similarly, renal angiomyolipomas were more common in women with TSC2 mutations compared with women with TSC1 mutations (29/30 [97%] vs. 6/12 [50%]; P = 0.01). There was no association between TSC mutation subtype and the presence of multifocal micronodular pneumocyte hyperplasia, sclerotic bone lesions, and skin or brain involvement. Serum VEGF-D (vascular endothelial growth factor-D) concentrations (median [95% confidence interval]) tended to be higher in patients harboring TSC2 mutations compared with patients with TSC1 mutations (725 pg/ml [612-1,317] vs. 331 pg/ml [284-406]; P = 0.03) and in patients with LAM compared with patients without LAM (725 pg/ml [563-1,609] vs. 429 pg/ml [357-773]; P = 0.02).Conclusions: LAM and angiomyolipomas are more common in women with TSC harboring TSC2 mutations compared with women with TSC1 mutations. Serum VEGF-D is a useful biomarker to suggest the presence of LAM in women with TSC.

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

Bronchial angiofibroma in tuberous sclerosis complex: A case report and literature review

Cutaneous angiofibroma is part of the classic triad of tuberous sclerosis complex (TSC). Angiofibroma is rarely reported to affect the mucous membranes of the trachea and bronchus. Tracheobronchial angiofibroma is also a hamartomatous manifestation of TSC. Considering the paucity of literature describing tracheal lesions in TSC, more case reports are needed to guide treatment planning. This case report adds to the existing clinical literature and provides a reference for clinical diagnosis.

Pulmonary Manifestations of Skin Disorders in Children

Systemic diseases often manifest with cutaneous findings. Many pediatric conditions with prominent skin findings also have significant pulmonary manifestations. These conditions include both inherited multisystem genetic disorders such as yellow-nail syndrome, neurofibromatosis type 1, tuberous sclerosis complex, hereditary hemorrhagic telangiectasia, Klippel-Trénaunay-Weber syndrome, cutis laxa, Ehlers-Danlos syndrome, dyskeratosis congenita, reactive processes such as mastocytosis, and aquagenic wrinkling of the palms. This overview discusses the pulmonary manifestations of skin disorders.

[Pulmonary lymphangioleiomyomatosis (LAM)]

Lymphangioleiomyomatosis (LAM) is a rare lung disease that mostly occurs in female patients. A total of 200-400 people are assumed to be infected in Germany. A sporadic form and a form associated with the tuberous sclerosis complex (TSC) can be separated. Mutations of the TSC‑1 and TSC‑2 genes are relevant. Morphologically, pulmonary multicysts and marginal micronodal proliferations of LAM cells are characteristic. Combinations with renal angiomyolipoma are typical and, in cases with TSC glioma, facial angiofibroma and ungual fibroma are seen. Prognosis is favorable (10-year survival: 80%) and with the use of mTORC1 inhibitors it could be improved. Lung transplantation can be considered in some cases.

The future is here: Integrating genetics into the pediatric pulmonary clinic

Recognition of underlying genetic etiologies of disease is increasing at an exponential rate, likely due to greater access to and lower cost of genetic testing. Monogenic causes of disease, or conditions resulting from a mutation or mutations in a single gene, are now well recognized in every subspecialty, including pediatric pulmonary medicine; thus, it is important to consider genetic conditions when evaluating children with respiratory disease. In the pediatric pulmonary clinic, genetic testing should be considered when multiple family members present with similar or related clinical features and when individuals have unusual clinical presentations, such as early-onset disease or complex, syndromic features. This review provides a practical guide for genetic diagnosis in the pediatric pulmonary setting, including a review of genetic concepts, considerations for test selection and results in interpretation, as well as an overview of genetic differential diagnoses for common pediatric pulmonary phenotypes. Genetic conditions that commonly present to the pediatric pulmonary clinic are reviewed in a companion article by Yonker et al.

Recognizing genetic disease: A key aspect of pediatric pulmonary care

Advancement in technology has improved recognition of genetic etiologies of disease, which has impacted diagnosis and management of rare disease patients in the pediatric pulmonary clinic. This review provides an overview of genetic conditions that are likely to present with pulmonary features and require extensive care by the pediatric pulmonologist. Increased familiarity with these conditions allows for improved care of these patients by reducing time to diagnosis, tailoring management, and prompting further investigation into these disorders.

Update on Hereditary Renal Cancer and Imaging Implications

Up to 8% of renal cancers are thought to have a hereditary component. Several hereditary renal cancer syndromes have been identified over the last few decades. It is important for the radiologist to be aware of findings associated with hereditary renal cancer syndromes to detect tumors early, enroll patients in appropriate surveillance programs, and improve outcomes for the patient and affected family members. This review discusses from a radiologist's perspective well-known hereditary renal cancer syndromes and emerging genetic mutations associated with renal cancer that are less well characterized, focusing on imaging features and known associations.

Therapeutic Targeting of the Secreted Lysophospholipase D Autotaxin Suppresses Tuberous Sclerosis Complex-Associated Tumorigenesis

Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterized by multiorgan hamartomas, including renal angiomyolipomas and pulmonary lymphangioleiomyomatosis (LAM). TSC2 deficiency leads to hyperactivation of mTOR Complex 1 (mTORC1), a master regulator of cell growth and metabolism. Phospholipid metabolism is dysregulated upon TSC2 loss, causing enhanced production of lysophosphatidylcholine (LPC) species by TSC2-deficient tumor cells. LPC is the major substrate of the secreted lysophospholipase D autotaxin (ATX), which generates two bioactive lipids, lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P). We report here that ATX expression is upregulated in human renal angiomyolipoma-derived TSC2-deficient cells compared with TSC2 add-back cells. Inhibition of ATX via the clinically developed compound GLPG1690 suppressed TSC2-loss associated oncogenicity in vitro and in vivo and induced apoptosis in TSC2-deficient cells. GLPG1690 suppressed AKT and ERK1/2 signaling and profoundly impacted the transcriptome of these cells while inducing minor gene expression changes in TSC2 add-back cells. RNA-sequencing studies revealed transcriptomic signatures of LPA and S1P, suggesting an LPA/S1P-mediated reprogramming of the TSC lipidome. In addition, supplementation of LPA or S1P rescued proliferation and viability, neutral lipid content, and AKT or ERK1/2 signaling in human TSC2-deficient cells treated with GLPG1690. Importantly, TSC-associated renal angiomyolipomas have higher expression of LPA receptor 1 and S1P receptor 3 compared with normal kidney. These studies increase our understanding of TSC2-deficient cell metabolism, leading to novel potential therapeutic opportunities for TSC and LAM. SIGNIFICANCE: This study identifies activation of the ATX-LPA/S1P pathway as a novel mode of metabolic dysregulation upon TSC2 loss, highlighting critical roles for ATX in TSC2-deficient cell fitness and in TSC tumorigenesis.

The Importance of Genetic Factors in the Management of Spontaneous Pneumothorax

Purpose of Review

Spontaneous pneumothoraces can be the presenting phenotype in a variety of different syndromic genetic conditions. Respiratory physicians therefore have the opportunity to diagnose and manage these patients early to prevent serious complications associated with these syndromes.

Recent Findings

The genetic syndromes that present with pneumothoraces can be split broadly between those resulting from defective extracellular matrix formation and those caused by defective tumour-suppressor pathways. When connective tissues are weakened, lifelong surveillance for arterial dilatation can be life-saving as surgical intervention is effective. Long-term aggressive treatment of blood pressure can also commence, although some controversy surrounds which drugs are most effective and precisely how these drugs modify disease progression. Rational treatments of syndromes in which tumour suppressor function is lost are being developed and, in some instances, can already be offered.

Summary

Careful clinical assessment of spontaneous pneumothorax may identify an underlying causal condition and facilitate life-saving intervention. Respiratory physicians must therefore be aware of these diseases and their diagnostic criteria.

IMPDH inhibitors for antitumor therapy in tuberous sclerosis complex

Recent studies in distinct preclinical tumor models have established the nucleotide synthesis enzyme inosine-5'-monophosphate dehydrogenase (IMPDH) as a viable target for antitumor therapy. IMPDH inhibitors have been used clinically for decades as safe and effective immunosuppressants. However, the potential to repurpose these pharmacological agents for antitumor therapy requires further investigation, including direct comparisons of available compounds. Therefore, we tested structurally distinct IMPDH inhibitors in multiple cell and mouse tumor models of the genetic tumor syndrome tuberous sclerosis complex (TSC). TSC-associated tumors are driven by uncontrolled activation of the growth-promoting protein kinase complex mechanistic target of rapamycin (mTOR) complex 1 (mTORC1), which is also aberrantly activated in the majority of sporadic cancers. Despite eliciting similar immunosuppressive effects, the IMPDH inhibitor mizoribine, used clinically throughout Asia, demonstrated far superior antitumor activity compared with the FDA-approved IMPDH inhibitor mycophenolate mofetil (or CellCept, a prodrug of mycophenolic acid). When compared directly to the mTOR inhibitor rapamycin, mizoribine treatment provided a more durable antitumor response associated with tumor cell death. These results provide preclinical support for repurposing mizoribine, over other IMPDH inhibitors, as an alternative to mTOR inhibitors for the treatment of TSC-associated tumors and possibly other tumors featuring uncontrolled mTORC1 activity.

Pneumothorax as a Presentation of Tuberous Sclerosis-Associated Lymphangioleiomyomatosis

Tuberous sclerosis complex (TSC) is a rare, autosomal dominant disorder with a recognized phenotypic variability with clinical manifestations developing continuously throughout life. The follow-up of TSC patients is challenging. The authors present a case with a definite diagnosis of TSC with known skin, renal, hepatic and neuropsychiatric involvement, whose diagnosis of TSC-associated lymphangioleiomyomatosis was establish at a late stage after the patient had presented with recurrent pneumothorax. Notwithstanding, mammalian target of rapamycin inhibition therapy was initiated.

Deceased Donor Renal Transplantation Combined with Bilateral Nephrectomy in a Patient with Tuberous Sclerosis and Renal Failure

Introduction

A 27-year-old female patient with known tuberous sclerosis complex (TSC), polycystic kidneys with multiple large bilateral angiomyolipomas, and failing renal functions with prehemodialysis values (urea: 19 mmol/L; creatinine: 317 μmol/L; CKD-EPI 0,27) was admitted to our department for pre-renal transplant evaluation. The patient was placed on the transplant waiting list as the living donor did not pass pretransplant workup and was subsequently contraindicated. Patient was placed on the “cadaverous kidney transplant waiting list”.

Method

Computed tomography angiography revealed symptomatic PSA in the right kidney angiomyolipoma (AML). The patient underwent urgent transarterial embolisation of the PSA's feeding vessel in the right kidney AML. Based on the “kidney transplant waiting list” order patient underwent a bilateral nephrectomy combined with transperitoneal renal allotransplantation of a cadaverous kidney graft through midline laparotomy, appendectomy, and cholecystectomy.

Results

Postoperative period was complicated by delayed graft function caused by acute tubular necrosis requiring postoperative hemodialysis. The patient was discharged on the 17th postoperative day with a good renal graft function. Patient's follow-up is currently 23 months with good graft function (urea: 9 mmol/L; creatinine: 100 μmol/L).

Conclusion

Renal transplantation combined with radical nephrectomy provides a definitive treatment for TSC renal manifestations.