Lymphangioleiomyomatosis: new insights

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.

Lymphangioleiomyomatosis: a clinical review

Lymphangioleiomyomatosis (LAM) is a diffuse cystic lung disease. There are two main types of LAM: sporadic, and LAM associated with the tuberous sclerosis complex (TSC), which is caused by mutations in the TSC1 and TSC2 genes. LAM is characterised by cystic lung disease resulting in progressive dyspnoea, renal angiomyolipomas and lymphatic complications. Pneumothorax occurs frequently (70%) and definitive management with pleurodesis is recommended as the risk of recurrence is high. Characteristic thin-walled cysts are seen on computed tomography and the presence of elevated serum levels of a vascular endothelial growth factor-D has good diagnostic specificity. Currently, no single clinical or serological factor has been shown to predict prognosis. However, over the past decade, significant advances in our understanding of the pathophysiology of LAM has led to improved recognition of this rare disease and identification of treatment options. Mechanistic target of rapamycin inhibitors slow the rate of lung function decline and can resolve chylous effusion and regress angiomyolipomas. Life expectancy in patients with LAM is favourable, with a mean transplant-free survival >20 years from the time of diagnosis. Continued advances in understanding the molecular basis of LAM will lead to improved therapeutic targets and the development of more robust prognostic indicators.

Educational aims

To illustrate the clinical features, common presentations and radiological features of LAMTo outline the diagnostic approach to LAM, including the role of VEGF-DTo review the current prognostic indicators in LAM, and outline the impact of lung function, hormonal status, VEGF-D and clinical presentation on outcomeTo inform clinicians on the management options for LAM both pharmacological and nonpharmacological.

A Stepwise Diagnostic Approach to Cystic Lung Diseases for Radiologists

Lung cysts are commonly seen on computed tomography (CT), and cystic lung diseases show a wide disease spectrum. Thus, correct diagnosis of cystic lung diseases is a challenge for radiologists. As the first diagnostic step, cysts should be distinguished from cavities, bullae, pneumatocele, emphysema, honeycombing, and cystic bronchiectasis. Second, cysts can be categorized as single/localized versus multiple/diffuse. Solitary/localized cysts include incidental cysts and congenital cystic diseases. Multiple/diffuse cysts can be further categorized according to the presence or absence of associated radiologic findings. Multiple/diffuse cysts without associated findings include lymphangioleiomyomatosis and Birt-Hogg-Dubé syndrome. Multiple/diffuse cysts may be associated with ground-glass opacity or small nodules. Multiple/diffuse cysts with nodules include Langerhans cell histiocytosis, cystic metastasis, and amyloidosis. Multiple/diffuse cysts with ground-glass opacity include pneumocystis pneumonia, desquamative interstitial pneumonia, and lymphocytic interstitial pneumonia. This stepwise radiologic diagnostic approach can be helpful in reaching a correct diagnosis for various cystic lung diseases.

A genome-wide association study implicates NR2F2 in lymphangioleiomyomatosis pathogenesis

INTRODUCTION

Lymphangioleiomyomatosis (LAM) occurs either associated with tuberous sclerosis complex (TSC) or as sporadic disease (S-LAM). Risk factors for development of S-LAM are unknown. We hypothesised that DNA sequence variants outside of TSC2/TSC1 might be associated with susceptibility for S-LAM and performed a genome-wide association study (GWAS).

METHODS

Genotyped and imputed data on 5 426 936 single nucleotide polymorphisms (SNPs) in 426 S-LAM subjects were compared, using conditional logistic regression, with similar data from 852 females from COPDGene in a matched case-control design. For replication studies, genotypes for 196 non-Hispanic White female S-LAM subjects were compared with three different sets of controls. RNA sequencing and immunohistochemistry analyses were also performed.

RESULTS

Two noncoding genotyped SNPs met genome-wide significance: rs4544201 and rs2006950 (p=4.2×10^-8 and 6.1×10^-9, respectively), which are in the same 35 kb linkage disequilibrium block on chromosome 15q26.2. This association was replicated in an independent cohort. NR2F2 (nuclear receptor subfamily 2 group F member 2), a nuclear receptor and transcription factor, was the only nearby protein-coding gene. NR2F2 expression was higher by RNA sequencing in one abdominal LAM tumour and four kidney angiomyolipomas, a LAM-related tumour, compared with all cancers from The Cancer Genome Atlas. Immunohistochemistry showed strong nuclear expression in both LAM and angiomyolipoma tumours.

CONCLUSIONS

SNPs on chromosome 15q26.2 are associated with S-LAM, and chromatin and expression data suggest that this association may occur through effects on NR2F2 expression, which potentially plays an important role in S-LAM development.

Pregnancy unmasking symptoms of undiagnosed lymphangioleiomyomatosis: Case report and review of literature

Cystic lung diseases are a group of disorders that appear similar on radiological studies on chest computed tomography. Each disorder is characterized by its own etiology, pathophysiology, course of progression and manifestation. Lymphangioleiomyomatosis (LAM) is one of the cystic lung diseases that can either be hereditary or sporadic. The sporadic form is a rare disease with no accurate prevalence reported but is believed to be less than 10 per million. LAM is associated with inappropriate activation of mammalian target of rapamycin (mTOR) signaling which regulates cellular growth. The sporadic form is almost confined to premenopausal female population and estrogen is believed to play an important role in the pathogenesis. Pregnancy and use of estrogen based oral contraceptives can aggravate symptoms of already existing LAM. Here we describe a case of LAM that was previously treated as asthma and was diagnosed after exacerbation of respiratory symptoms after pregnancy. We offer a review of the medical literature regarding the etiology, clinical course, diagnosis and treatment of LAM.

Consideration of underlying causes of pneumothoraces in patients presenting with their first pneumothorax

We report a case of cardiac arrest secondary to pneumothorax. The patient failed to improve, and further investigation showed an underlying condition predisposing the patient to the development of pneumothoraces – lymphangioleiomyomatosis. This highlights the importance of follow-up and investigation in patients presenting with their first pneumothorax.

Thoracic involvement in generalised lymphatic anomaly (or lymphangiomatosis)

Generalised lymphatic anomaly (GLA), also known as lymphangiomatosis, is a rare disease caused by congenital abnormalities of lymphatic development. It usually presents in childhood but can also be diagnosed in adults. GLA encompasses a wide spectrum of clinical manifestations ranging from single-organ involvement to generalised disease. Given the rarity of the disease, most of the information regarding it comes from case reports. To date, no clinical trials concerning treatment are available. This review focuses on thoracic GLA and summarises possible diagnostic and therapeutic approaches.

Possible diagnostic and therapeutic approaches to generalised lymphatic anomaly (lymphangiomatosis)http://ow.ly/4n4pgU

Combined Smooth Muscle and Melanocytic Differentiation in Lymphangioleiomyomatosis

Pulmonary lymphangioleiomyomatosis (LAM) is characterized by abnormal proliferation of immature-looking smooth muscle (SM)-like cells (LAM cells), leading to lung destruction and cyst formation. In addition to expressing some SM markers, scattered LAM cells express the melanocytic maker gp100, which is recognized by antibody HMB45, suggesting that at least a few LAM cells may have melanocytic differentiation. Here we immunostained 26 LAM samples for several melanocyte-related proteins. These studies showed that all LAM cells express tetraspanin CD63, a melanoma-associated protein that belongs to the transmembrane 4 superfamily. The majority of LAM cells also immunoreacted with PNL2, an antibody against a yet uncharacterized melanocytic antigen. Furthermore, we examined the co-expression of PNL2 and Ki-67, an indicator of cell proliferation, and found that PNL2-positive LAM cells showed a significantly lower proliferation rate compared with their negative counterparts. Our findings shed new light on the nature of the LAM cells by demonstrating their combined SM and melanocytic differentiation and the existence of subpopulations with different proliferative potential. Furthermore, these studies provided two new antibodies useful in the diagnosis of LAM.

A practical approach to high-resolution CT of diffuse lung disease

Diffuse lung disease presents a variety of high-resolution CT findings reflecting its complex pathology, and provides diagnostic challenge to radiologists. Frequent modification of detailed pathological classification makes it difficult to keep up with the latest understanding. In this review, we describe a practical approach to high-resolution CT diagnosis of diffuse lung disease, emphasizing (1) analysis of "distribution" of the abnormalities, (2) interpretation of "pattern" in relation to distribution, (3) utilization of associated imaging findings and clinical information, and (4) chronicity of the findings. This practical approach will help radiologists establish a way to interpret high-resolution CT, leading to pin-point diagnosis or narrower differential diagnoses of diffuse lung diseases.

[A clinicopathological analysis of pulmonary lymphangioleiomyomatosis]

BACKGROUND AND OBJECTIVE

Pulmonary lymphangioleiomyomatosis (PLAM) is a rare tumor with unique clinicopathological features. The aim of this study is to investigate the clinicopathological features, the diagnosis and differential diagnosis of pulmonary lymphangioleiomyomatosis.

METHODS

Three cases of PLAM were analyzed by light microscopy, immunohistochemistry and their clinical data, and the relative literatures were reviewed.

RESULTS

Three cases of patients suffered from PLAM were the women in their reproductive aged, from 27 years to 45 years (mean 37.7 years), two cases of the HRCT showed bilateral diffuse cystic airspaces changed, and one case was the pneumothorax. The histopathological examination revealed the tumor was composed of the variably sized cystic spaces are lined by plaque-like or nodular aggregates of endothelial cells and the hyperplasia, smooth-muscle-like spindle cells which was along with the bronchi and the vessels. The immunohistochemistry showed that Des, Caldes, SMA, MSA, HMB-45, CD63, Vim, ER and PR were positive in the hyperplasia spindle cells, and there was no expression of MRAT-1. The FVIII, CD34 were positive in the capillary endothelial cells, and the D2-40 was positive in the lymphatic vessels. All the patients were alive without the recrudescence of the PLAM since the diagnosis, about 3 months to 25 months, and there was no LAM in their other systems.

CONCLUSIONS

The most significant histopathological feature of pulmonary lymphangioleiomyomatosis was the progressive invasion of smooth muscle cells into the lymphatic vessels, and the blood vessels. The majority of the cases occur in the lungs of the women in the predominantly premenopausal and middle-age. It is a poor prognosis due to the progressive respiratory failure.

A nationwide survey of lymphangioleiomyomatosis in Korea: recent increase in newly diagnosed patients

In 2007, the Korean Interstitial Lung Disease Society had collected clinical data of patients who have diagnosed as Lymphangioleiomyomatosis (LAM) since 1990 through nationwide survey, which showed that LAM patients had increased sharply after 2004. The present study was performed to show the clinical features of Korean patients with LAM, and to establish the reason for the recent increase in the diagnosis. All 63 patients were women and the mean age at diagnosis was 36 yr. The most common presenting symptom was dyspnea and 8 patients had tuberous sclerosis complex. The survival rate at 5 yr after diagnosis was 84%. Compared with patients diagnosed after 2004 (n=34), the patients diagnosed before 2004 (n=29) complained with dyspnea more (P=0.016) and had lower FEV(1)% predicted (P=0.003), and DLco% predicted (P=0.042). The higher proportion of patients diagnosed after 2004 showed the normal chest radiography, and they were detected by routine chest CT screening (P=0.016). This study showed that clinical features of Korean patients with LAM were not different from those reported elsewhere. It is concluded that the reason for the increase of newly diagnosed patients is the result of increase in detection of the early stage LAM by the widespread use of chest CT screening.

The natural history of lymphangioleiomyomatosis: markers of severity, rate of progression and prognosis

Lymphangioleiomyomatosis (LAM) is a multisystem disease of women, characterized by proliferation of abnormal smooth muscle-like cells (LAM cells) that can metastasize, leading to the formation of lung cysts, fluid-filled cystic structures in the axial lymphatics (e.g., lymphangioleiomyomas), and angiomyolipomas, benign tumors usually involving the kidneys, comprising LAM cells and adipocytes, intermixed with incompletely developed vascular structures. LAM occurs sporadically or in association with tuberous sclerosis complex, an autosomal dominant syndrome characterized by hamartoma-like tumor growths. LAM may present with progressive dyspnea, recurrent pneumothorax, chylothorax, or abdominal hemorrhage. Computed tomography scans show thin-walled cysts scattered throughout the lungs, abdominal angiomyolipomas, and lymphangioleiomyomas. Pulmonary function tests show reduced flow rates (FEV(1)) and diffusion capacity (DL(CO)). Exercise testing may reveal gas exchange abnormalities, ventilatory limitation, and hypoxemia, which can occur with near-normal lung function. Methods used to grade the severity of disease are the LAM histology score, semiquantitative and quantitative computer tomography, pulmonary function testing, and cardiopulmonary exercise testing. Currently, progression of disease is best assessed by serial measurements of FEV(1), DL(CO), and exercise performance. New quantitative radiographic techniques that may offer advantages over physiologic testing are now available. Several potential biomarkers, such as LAM cells in peripheral blood, urine, and chyle and chemokines, vascular endothelial growth factors, and matrix metalloproteinases, may be useful as diagnostic tools or markers of organ involvement, disease severity, and progression.

Pulmonary lymphangioleiomyomatosis: unusual manifestations of multiple large pulmonary nodules with retroperitoneal lymph node involvement mimicking metastatic malignancy

Pulmonary lymphangioleiomyomatosis (LAM) is a rare, idiopathic disorder that predominantly affects the lung parenchyma of women of childbearing age. While the characteristic radiographic finding of pulmonary LAM consists of multiple well-defined thin-walled cysts, we describe a very unusual case of pulmonary LAM with multiple bilateral large pulmonary nodules and retroperitoneal involvement mimicking metastatic malignancy. A 48-year-old woman who had never smoked with a history of bilateral pneumothorax presented with progressive exertional dyspnea and abdominal discomfort. Imaging studies revealed multiple enlarged retroperitoneal lymph nodes, ascites and bilateral multiple large pulmonary nodules ranging from 3 to 18 mm in diameter. Exploratory laparoscopic surgery for intra-abdominal lesions and video-assisted thoracoscopic wedge resection of lung nodules were carried out to rule out metastatic malignancy. Pathology showed benign looking smooth muscle cell proliferation and immunoreactivity for α-smooth muscle actin and HMB-45 in both specimens. After treatment with GnRH antagonist, the patient was well over a 6-month period without evidence of disease progression.

The clinical spectrum of lymphatic disease

Lymphatic disease is quite prevalent, and often not well clinically characterized. Beyond lymphedema, there is a broad array of human disease that directly or indirectly alters lymphatic structure and function. The symptomatic and objective presentation of these patients can be quite diverse. In this review, we have attempted to provide a systematic overview of the subjective and objective spectrum of lymphatic disease, with consideration of all of the categories of disease that primarily or secondarily impair the functional integrity of the lymphatic system. Lymphedema is discussed, along with chromosomal disorders, lymphangioma, infectious diseases, lymphangioleiomyomatosis, lipedema, heritable genetic disorders, complex vascular malformations, protein-losing enteropathy, and intestinal lymphangiectasia.

Lymphangioleiomyomatosis: A review

Lymphangioleiomyomatosis (LAM) is a rare disease, of unknown etiology, affecting women almost exclusively. Microscopically, LAM consists of a diffuse proliferation of smooth muscle cells. LAM can occur without evidence of other disease (sporadic LAM) or in conjunction with tuberous sclerosis complex (TSC). TSC is an autosomal dominant tumor suppressor gene syndrome characterized by seizures, mental retardation, and tumors in the brain, heart, skin, and kidney. LAM commonly presents with progressive breathlessness or with recurrent pneumothorax, chylothorax, or sudden abdominal hemorrhage. Computed tomography (CT) scans show numerous thin-walled cysts throughout the lungs, abdominal angiomyolipomas, and lymphangioleiomyomas. No effective treatment currently exists for this progressive disorder. The prevalence of lymphangioleiomyomatosis is probably underestimated based on its clinical latency and the absence of specific laboratory tests. With the utilization of international LAM data registries the "classical" picture of the disorder appears to be evolving as a larger number of patients are evaluated. An increased awareness of LAM and its common clinical presentation may advance the development of new therapeutic strategies and reduce the number of mistakenly diagnosed patients.

Challenges in pulmonary fibrosis. 3: Cystic lung disease

Cystic lung disease is a frequently encountered problem caused by a diverse group of diseases. Distinguishing true cystic lung disease from other entities, such as cavitary lung disease and emphysema, is important given the differing prognostic implications. In this paper the features of the cystic lung diseases are reviewed and contrasted with their mimics, and the clinical and radiographic features of both diffuse (pulmonary Langerhans' cell histiocytosis and lymphangioleiomyomatosis) and focal or multifocal cystic lung disease are discussed.

Identification of the benign mesenchymal tumor gene HMGA2 in lymphangiomyomatosis

The normal expression pattern of HMGA2, an architectural transcription factor, is primarily restricted to cells of the developing mesenchyme before their overt differentiation during organogenesis. A detailed in situ hybridization analysis showed that the undifferentiated mesoderm of the embryonic lung expressed Hmga2 but it was not expressed in the newborn or adult lung. Previously, HMGA2 was shown to be misexpressed in a number of benign, differentiated mesenchymal tumors including lipomas, uterine leiomyomas, and pulmonary chondroid hamartomas. Here, we show that HMGA2 is misexpressed in pulmonary lymphangiomyomatosis (LAM), a severe disorder of unknown etiology consisting of lymphatic smooth muscle cell proliferation that results in the obstruction of airways, lymphatics, and vessels. Immunohistochemistry was done with antibodies to HMGA2 and revealed expression in lung tissue samples obtained from 21 patients with LAM. In contrast, HMGA2 was not expressed in sections of normal adult lung or other proliferative interstitial lung diseases, indicating that the expression of HMGA2 in LAM represents aberrant gene activation and is not due solely to an increase in cellular proliferation. In vivo studies in transgenic mice show that misexpression of HMGA2 in smooth muscle cells resulted in increased proliferation of these cells in the lung surrounding the epithelial cells. Therefore, similar to the other mesenchymal neoplasms, HMGA2 misexpression in the smooth muscle cell leads to abnormal proliferation and LAM tumorigenesis. These results suggest that HMGA2 plays a central role in the pathogenesis of LAM and is a potential candidate as a therapeutic target.

Pleural disease in lymphangioleiomyomatosis

Pleural disease is a common complication of lymphangioleiomyomatosis (LAM). The incidence and recurrence rates of secondary spontaneous pneumothorax in LAM are the highest among chronic pulmonary disorders. Most patients have at least one pneumothorax before LAM is diagnosed, and pneumothorax is often the sentinel event that leads to the diagnosis. Although early, definitive treatment for recurrent pneumothorax by pleurodesis is recommended, the failure rate for chemical and surgical approaches is high. Chylothorax occurs owing to obstruction of lymphatics by proliferating smooth muscle cells and often requires pleurodesis to control expanding and recurrent effusions. Because of the rarity of the LAM, few data exist on whether the occurrence of pleural complications in LAM accelerates functional decline or portends a worse prognosis.

Iatrogenic bilateral pneumothorax following unilateral transbronchial lung biopsy

Bilateral pneumothoraces are recognized complications of thoracic procedures in patients who have undergone heart or heart-lung transplantation. Bilateral simultaneous pneumothoraces developing following a unilateral transbronchial lung biopsy in the absence of previous thoracic surgery has not been reported previously.

Lung disease 35 years after aspiration of activated charcoal in combination with pulmonary lymphangioleiomyomatosis. A histological and clinicopathological study with scanning electron microscopic evaluation and element analysis

Activated charcoal provides effective treatment for most toxic ingestions. Accidental aspiration of activated charcoal is rare. Previously, there have been a few single cases reported on charcoal-related pulmonary complications. We describe an unusual case of pulmonary lesions 35 years after accidental aspiration of activated charcoal. The 38-year-old female patient presented with recurrent pneumothorax. A routinely performed chest roentgenogram revealed pulmonary lesions, highly suggestive to lymphangioleiomyomatosis (LAM). Histopathological investigation of the lung tissue demonstrated some features of LAM but showed prominent pneumoconiotic lesions with cystic tissue destruction. The pneumoconiotic reaction was characterized by prominent black deposits accompanied by foreign-body granuloma formation and minimal fibrosis. Scanning electron microscopic investigation of these deposits showed particles measuring up to 300 microm in greatest diameter. Energy-dispersive X-ray spectra of these particles revealed carbon-rich material, presumably charcoal. The aspiration event was confirmed by the clinical history. To our knowledge, this is the first report not only on a long-term follow-up after aspiration of activated charcoal but also on charcoal-related pulmonary lesions in combination with LAM.

Patient perspectives on management of pneumothorax in lymphangioleiomyomatosis

STUDY OBJECTIVES

The American College of Chest Physicians Delphi Consensus Statement on management of spontaneous pneumothorax recommended pleurodesis after the first secondary spontaneous pneumothorax to prevent recurrence, and evaluation of patients' perspectives regarding pneumothorax treatment was identified as a future research priority. Patients with lymphangioleiomyomatosis (LAM) are an ideal population for performing these studies, since pneumothorax occurs and recurs more commonly in LAM than in any other chronic pulmonary disorder.

STUDY DESIGN AND PARTICIPANTS

A 23-item questionnaire evaluating opinions of pneumothorax treatment was distributed to 615 patients in the LAM Foundation patient database, with a response rate of 52%.

RESULTS

Of respondents, 69% (216 of 314 patients) reported a history of radiographically documented pneumothorax, and 181 patients (84%) reported at least one pleurodesis procedure. Neither a history of pneumothorax nor surgical management of pneumothorax affected reported oxygen use or perception of overall lung function, yet 41% thought that their pneumothorax had contributed to a decline in lung function. Few patients (12%) worried frequently about a pneumothorax developing, but one third made lifestyle modifications due to fear of pneumothorax. Extensive pain associated with chest tube placement and inadequate pain management throughout treatment for pneumothorax were frequent concerns. Only 25% of respondents thought that pleurodesis was appropriate for a first pneumothorax, while 60% favored pleurodesis for a second pneumothorax. Despite the apparent reluctance to undergo pleurodesis, most patients agreed that pleurodesis helps prevent pneumothorax recurrence. One third of patients believed that their physicians did not consider their preferences regarding pneumothorax management.

CONCLUSIONS

LAM patients and physicians may have different views about the significance of pneumothorax, in that most patients appear to favor a conservative initial approach to pneumothorax management. In conjunction with appropriate pain management, a better understanding of patients' perspectives will facilitate cooperative decision making and may ultimately improve clinical outcomes in LAM related to pneumothorax.

Management of pneumothorax in lymphangioleiomyomatosis: effects on recurrence and lung transplantation complications

STUDY OBJECTIVES

Pneumothorax is a common complication of lymphangioleiomyomatosis (LAM), and the optimal approach to its treatment and prevention is unknown. Chemical or surgical pleurodesis are often required to prevent recurrence. However, their efficacy in LAM is unclear, and whether they contribute to perioperative complications during lung transplantation is uncertain.

SETTING

The LAM Foundation database of registered patients.

DESIGN

A questionnaire was sent to all registered patients who had at least one pneumothorax to determine rates and patterns of recurrence and efficacy of interventions. A second questionnaire was sent to registered LAM patients who received a lung transplant.

PATIENTS OR PARTICIPANTS

Of 395 registered patients, 260 patients (66%) reported at least one pneumothorax during their lifetime, 193 of whom (74%) completed the questionnaire. Of the 85 lung transplant patients who were sent a separate questionnaire, 80 patients (94%) responded.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Of the 193 respondents to the pneumothorax questionnaire, data on 676 episodes of pneumothorax were collected. Eighty-two percent (158 of 193 patients) had their first pneumothorax prior to a diagnosis of LAM. One hundred forty patients (73%) had at least one additional pneumothorax, either an ipsilateral recurrence (99 of 140 patients, 71%) or a contralateral pneumothorax (104 of 140 patients, 74%). Recurrence rates were 66% after conservative therapy, 27% after chemical pleurodesis, and 32% after surgery. In patients who had undergone lung transplantation, prior chemical or surgical pleurodesis was performed in 45 of 80 patients (56%). Fourteen of 80 patients (18%) reported pleural-related postoperative bleeding, 13 of whom (93%) had prior pleurodesis.

CONCLUSIONS

Chemical pleurodesis or surgery are equally effective and better than conservative therapy in preventing recurrence of pneumothorax in LAM. Due to the high recurrence rate, either procedure should be considered for the initial pneumothorax in these patients. However, both contribute to increased perioperative bleeding following lung transplantation, with no effect on length of hospital stay.

Lymphangioleiomyomatosis: Radiologic-Pathologic Correlation

Lymphangioleiomyomatosis (LAM) is an uncommon interstitial lung disease that exclusively affects women, usually during their reproductive years. LAM is characterized pathologically by abnormal proliferation of LAM cells in the lungs and in thoracic and retroperitoneal lymphatics. Thirty-three cases of LAM were reviewed retrospectively for clinical and radiologic findings. Twenty-eight (85%) of 33 women (aged 21-62 years; mean, 37.5 years) were symptomatic. Radiographs (n = 32) demonstrated reticular opacities in 21 (66%) patients, large lung volumes in 17 (53%), pleural effusion in 14 (44%), and pneumothorax in 13 (41%). High-resolution CT (n = 15) and conventional CT (n = 3) showed 2-5-mm bilateral thin-walled cysts in all patients and cysts that were 6-12 mm or larger in patients with severe lung involvement. CT depicted diffuse lung involvement by cysts in nine (50%) patients, relative sparing of lung apices in seven (39%), and relative sparing of lung bases in two (11%). Pleural effusion and pneumothorax were seen at CT in four (22%) and three (17%) patients, respectively. Four cases of tuberous sclerosis complex-associated LAM (TSC-LAM) (women aged 27-50 years; mean, 35.7 years) were similarly reviewed. Three (75%) were symptomatic. Radiographs (n = 4) demonstrated reticular opacities in three (75%) and large lung volumes in two (50%). All high-resolution CT (n = 3) and conventional CT (n = 1) studies showed 2-5-mm bilateral thin-walled cysts and cysts that were 6-12 mm or larger in two patients with severe lung involvement. Pleural effusion and pneumothorax were demonstrated at CT in three (75%) and two (50%) patients, respectively. LAM and TSC-LAM affect symptomatic women who often exhibit reticular opacities and large lung volumes at radiography and bilateral uniform small thin-walled cysts at CT. Large (>12 mm) cysts occur in patients with severe cystic lung involvement. Pneumothorax and pleural effusion are common associated findings.

Thoracic lymphatic disorders

Thoracic complications of lymphatic disorders can culminate in respiratory failure and death and should be considered in any patient with a lymphatic disease and clinical or radiographic evidence of chest disease. Congenital lymphatic disorders are being increasingly recognized in the adult population. The spectrum of thoracic manifestations of lymphatic disorders ranges from incidental radiographic findings to diffuse lymphatic disease with respiratory failure. This article serves to review some recent advances that allow improved diagnosis and management of thoracic lymphatic disorders. Herein, we describe their anatomical and physiologic effects, the time course of their progression, and the therapies that are currently available. The management of malignant (cancerous) lymphatic disorders of the thorax is beyond the scope of this paper.

Pleural effusion in interstitial lung disease

PURPOSE OF REVIEW

This review reports recent information on the occurrence of pleural effusions in association with disorders that produce interstitial parenchymal lung disease.

RECENT FINDINGS

The occurrence of effusions has been expanded to include systemic sclerosis, polymyositis-dermatomyositis, several drugs, and several miscellaneous causes of interstitial lung disease (ILD).

SUMMARY

Pleural effusions occur in patients with various forms of interstitial lung disease. The effusions require a clinical evaluation to exclude complications of therapy and coexisting conditions unrelated to the underlying ILD.

Extrapulmonary presentation of asymptomatic pulmonary lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare parenchymal lung disease, which affects young women of childbearing age and is characterized pathologically by proliferation of interstitial smooth muscle and formation of cysts in the lung. While LAM is usually predominantly a respiratory disorder, it can also initially involve other extrapulmonary organs. We report the case of a 35-year-old Chinese woman, who presented with a 4-week history of left thigh swelling which was found to be secondary to compression of pelvic veins by a mass lesion. The latter was found histologically to show LAM. Despite the patient being asymptomatic and displaying normal lung function, a thoracic high resolution CT scan showed typical features of early LAM. This case further illustrates that LAM can have multisystem involvement, and demonstrates the importance of being aware of the diagnosis in cases presenting with extrapulmonary manifestation, in order that patients are diagnosed and managed appropriately.

Transforming Growth Factor-β 1 and Extracellular Matrix-Associated Fibronectin Expression in Pulmonary Lymphangioleiomyomatosis

STUDY OBJECTIVES

Lymphangioleiomyomatosis (LAM) is a rare disorder of unknown etiology, affecting almost exclusively women of childbearing age, that is associated with the proliferation of spindle cells and cystic changes in the affected lung. The underlying processes that contribute to this disease are poorly understood. Transforming growth factor (TGF)-beta(1) is a potent cytokine that promotes mesenchymal cell proliferation and regulates the synthesis of extracellular matrix (ECM) components, particularly fibronectins. Herein, we evaluate the expression of TGF beta(1) and matrix-associated fibronectin in lung specimens demonstrating LAM.

DESIGN

Lung biopsy specimens that were confirmed to contain pathologic LAM cells were obtained from 13 patients. The specimens were submitted to immunohistochemical evaluation for TGF beta(1) and fibronectin, as well as the typical markers of LAM cells. Healthy lung parenchyma surrounding resected neoplasms was studied in a parallel fashion as control tissues.

MEASUREMENTS AND RESULTS

In all 13 LAM cases and in healthy lung parenchyma, we demonstrated that TGF beta(1) localized consistently to airway epithelial cells. However, in LAM tissues, matrix-associated TGF beta(1) was also consistently found in regions containing pathologic LAM cells. Notably, more abundant TGF beta(1) was observed in highly cellular areas compared to the walls of chronic cystic regions in LAM tissues. Fibronectin, a matrix component that is strongly expressed in response to active TGF beta(1) was found to consistently colocalize with this protein in these highly cellular regions, supporting TGF beta(1) activity in these regions. The markers of proliferating LAM cells, including proliferating cell nuclear antigen, were also markedly present in these highly cellular LAM regions.

CONCLUSION

These studies suggest that the proliferation of aberrant LAM cells may be associated with altered regional expression of TGF beta(1) and related ECM proteins.

Pulmonary lymphangioleiomyomatosis

We retrospectively evaluated the high-resolution computed tomographic (HRCT) findings in 11 women patients with pulmonary lymphangioleiomyomatosis (LAM). Numerous, thin-walled cysts distributed diffusely throughout the lungs and ranged in size from a few millimeters to several centimeters were seen on HRCT in all patients. Other findings at HRCT included interlobular septal thickening (six patients), ground-glass opacity (one patient) and architectural distortion (one patient). Our study found that HRCT imaging findings were similar to the literatures reported, except that majority of our cases also have interstitial changes. HRCT may help establish this diagnosis when diagnosis by clinical findings is uncertain and chest radiographs showed normal or nonspecific findings.

Uterine leiomyoma in the Eker rat: A unique model for important diseases of women

Eker rats carry a defect in the Tsc-2 tumor suppressor gene and female Eker rats develop uterine leiomyoma with a high frequency. The presentation, response to hormones and molecular alterations in these mesenchymal smooth muscle tumors, closely resembles their cognate human disease. Female rats and tumor-derived cell lines from Eker rat leiomyomas (ELT lines) have been developed as an in vivo/in vitro model system for preclinical studies to identify novel therapeutic agents for this disease and for studying disease pathogenesis. In addition to serving as a model for uterine leiomyoma, Eker rats have proven valuable for studying lymphangioleiomyomatosis, a related proliferative smooth muscle disease of women.

Lymphangioleiomyomatosis and SZ alpha(1)-antitrypsin disease: a unique combination?

We describe a case of a 37-year-old female ex-smoker with lymphangioleiomyomatosis and SZ alpha(1)-antitrypsin disease who underwent successful bilateral sequential lung transplantation. While this disease combination has not been described previously, we recommend vigilance for the possibility of such combinations in patients with chronic lung disease. The possible mechanisms of interaction resulting from both disease processes are discussed.

Lymphangioleiomyomatosis initially presenting with abdominal pain: a case report

Lymphangioleiomyomatosis (LAM) is a rare idiopathic disease characterized by hamartomatous smooth muscle proliferation of the lymph node, lymphatics, blood vessels as well as airways within the lungs, mediastinum and abdomen. It exclusively affects women during the reproductive period. Though extrapulmonary manifestations have been reported, the initial presentation of LAM as abdominal pain is extremely rare. To our knowledge, there are only three cases with LAM presenting first with abdominal symptoms so far [Chest 106 (1994) 267; Eur J Radiol 14 (1992) 192; Eur J Surg 157 (1991) 36]. We describe a case of LAM suffering from abdominal pain followed by pulmonary symptoms and the diagnosis was not made until pathohistological examination.

Tissue inhibitor of metalloproteinase-3 downregulation in lymphangioleiomyomatosis: potential consequence of abnormal serum response factor expression

Pulmonary lymphangioleiomyomatosis (LAM) is characterized by abnormal smooth muscle-like cell proliferation leading to tissue destruction and cyst formation. We demonstrate that serum response factor (SRF), a critical smooth muscle transcription factor, is overexpressed in LAM cells. To determine whether abnormal SRF levels might have a pathogenic role in LAM, we transfected SRF into mouse lung fibroblasts and performed a cDNA array analysis. High SRF level upregulated the expression of matrix metalloproteinase (MMP)-2 and MMP-14, two MMPs previously shown to be increased in LAM. In addition, SRF down-regulated tissue inhibitor of metalloproteinase (TIMP)-3, one of their inhibitors. TIMP-3 inhibition was further confirmed by reverse transcriptase/polymerase chain reaction, immunoblotting, and immunostaining of human lung fibroblasts transfected with SRF fused to DsRed2 (a red variant of green fluorescent protein). To determine the in vivo significance of our findings, we immunostained 12 LAM cases for TIMP-3. In eight of them, TIMP-3 was ubiquitously present in normal lung parenchyma, but it was absent in LAM lesions. In the remaining cases, including two out of five normal control lungs, the antibody immunoreacted exclusively with elastin, probably due to suboptimal tissue processing. Because timp-3-null mice develop spontaneous emphysema, our findings suggest that SRF-mediated TIMP-3 inhibition might contribute to the tissue damage seen in LAM.

Lymphangioleiomyomatosis: pulmonary and abdominal findings with pathologic correlation

Lymphangioleiomyomatosis (LAM) is a rare disease characterized by pulmonary cysts at computed tomography (CT) and proliferation of abnormal smooth muscle cells at lung biopsy. Almost all patients are female, and all have pulmonary cysts at high-resolution CT. Although the presence of cysts may be suggested at conventional CT or chest radiography, high-resolution CT is superior for cyst detection and is essential for diagnosis. The cysts are typically round; in most cases, the cyst wall is barely seen at thin-section CT. They are typically diffusely distributed throughout the central and peripheral lung parenchyma. The lung bases are affected in all patients. Some patients also have increased lung attenuation or a reticular pattern. Expiratory CT shows no air trapping between the cysts, and most of the cysts decrease in size. Pneumothorax, pleural effusion, and chylothorax are complications of LAM. Certain abdominal findings may provide additional corroborative evidence of the diagnosis. Renal angiomyolipomas, the most frequent abdominal lesions, usually manifest as asymptomatic, small, bilateral tumors of fat attenuation in the renal cortex. Lymphangiomas are cystic retroperitoneal masses that occur in up to 20% of patients. Other CT findings are hypo- or hyperattenuating lymph nodes, a dilated thoracic duct, and ascites.

Basic fibroblast growth factor and its receptors in idiopathic pulmonary fibrosis and lymphangioleiomyomatosis

Basic fibroblast growth factor (bFGF) is a potent mitogenic factor for smooth muscle cells, myofibroblasts, and fibroblasts, proliferation of which is a hallmark of idiopathic pulmonary fibrosis (IPF) and lymphangioleiomyomatosis (LAM). Mast cells produce bFGF and have been associated with pulmonary fibrosis. We hypothesize that smooth muscle cell/myofibroblast-like cells will be spatially associated with bFGF-containing mast cells and that bFGF receptors will be expressed on the effector cells in IPF and LAM. We performed quantitative immunohistochemistry for bFGF, mast cell tryptase, smooth muscle actin for smooth muscle cell/myofibroblast-like cells, and fibroblast growth factor receptors (Flg, Bek) and measured collagen and elastic fiber in lung sections from IPF (n = 14), LAM (n = 9), and control lung (n = 10). IPF and LAM lung contained more smooth muscle cell/myofibroblast-like cells than did control lung. bFGF-containing mast cells were abundant both in IPF and LAM and were associated with collagen, elastic fibers, and smooth muscle cell/myofibroblast-like cells in IPF. Flg was expressed on epithelial cells, endothelial cells, smooth muscle cell/myofibroblast-like cells, and macrophages in IPF. In LAM, Flg was expressed on epithelial cells adjacent to smooth muscle cell/myofibroblast-like cell aggregates. Bek was expressed dominantly on smooth muscle cell/myofibroblast-like cells in LAM and on smooth muscle cell/myofibroblast-like cells as well as neutrophils in IPF. These data suggest that mast cell-derived bFGF might exert fibrogenic, proliferative effects on smooth muscle cell/myofibroblast-like cells through its receptors.

Giles F. Filley Lecture. Genetics and gene expression in lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a disease of unknown etiology that is characterized by the proliferation of abnormal smooth muscle cells (LAM cells) in the lung, which leads to cystic parenchymal destruction and progressive respiratory failure. Recent evidence suggests that the proliferative and invasive nature of LAM cells may be due, in part, to somatic mutations in the TSC2 gene, which has been implicated in the pathogenesis of tuberous sclerosis complex. Here, we describe the clinical and molecular characteristics of LAM, as well as the efforts now under way to understand the genetic and biochemical factors that lead to progressive pulmonary destruction and, ultimately, to lung transplantation or death.

Lymphangioleiomyomatosis and tuberous sclerosis

Tuberous sclerosis (TSC) is an inherited disorder best known for its association with severe learning difficulties, epilepsy, behavioural problems, skin and renal pathology Lymphangioleiomyomatosis (LAM), characterized by alveolar smooth muscle proliferation and cystic destruction of parenchyma, occurs as an infrequent symptomatic pulmonary complication in TSC and as a very rare sporadic disease in those without signs of TSC. Considered a generalized and progressive cystic lung disease that is difficult to treat with a poor prognosis, it has been reported almost exclusively in women, most commonly presenting with dyspnoea and pneumothorax in those of childbearing age. We investigated the clinical features and prognosis of LAM in patients with TSC including the effects of treatment, stratified by the method of diagnosis of LAM (i.e. histological or radiological). We found histological proof of diagnosis in 10 of 21 patients with TSC and symptomatic lung disease, onset in childhood in four, three males with LAM, individuals with apparently focal disease, great variation in clinical course and no clear treatment benefit. In those with TSC, symptomatic LAM is infrequent but causes a significant morbidity and mortality It was not possible to detect predisposing factors, other than being female. Males with apparent LAM should be rigorously investigated.

Pulmonary function tests in interstitial lung disease: what role do they have?

Pulmonary function tests have been widely accepted and utilized in the management of interstitial lung diseases. Although the tests performed have changed little over the past several decades, extensive literature has been published highlighting their clinical role in the diagnosis, staging, prognostication, and follow-up of patients with a wide variety of interstitial lung diseases.

Chromosome 16 loss of heterozygosity in tuberous sclerosis and sporadic lymphangiomyomatosis

In previous work we found loss of heterozygosity (LOH) of the wild-type TSC2 allele in the abnormal pulmonary smooth muscle cells and renal angiomyolipoma cells from patients with sporadic pulmonary lymphangiomyomatosis (LAM). Here we report TSC2 LOH in microdissected pulmonary LAM cells from a patient with tuberous sclerosis complex (TSC), demonstrating for the first time that the two-hit tumor suppressor gene model applies to the TSC-associated, as well as sporadic LAM. We also compared the chromosome 16 LOH region between angiomyolipoma and pulmonary LAM from two patients with sporadic LAM. Previously we found that these patients had TSC2 mutations and TSC2 LOH in their angiomyolipomas and pulmonary LAM cells but not in normal lung or kidney cells. This suggests that pulmonary LAM may result from the migration of smooth muscle cells from renal angiomyolipomas to the lung. In this case, one would predict that the angiomyolipoma and LAM cells would have identical LOH patterns. We found that at each chromosome 16 marker, the results were concordant between angiomyolipoma and LAM. This is consistent with a model in which pulmonary LAM cells and angiomyolipoma cells have a common genetic origin.

Frequency and CT findings of recurrent disease after lung transplantation

PURPOSE

To determine the frequency and computed tomographic (CT) findings of recurrence of the primary disease after lung transplantation at six North American lung transplantation centers.

MATERIALS AND METHODS

Medical records of 1,394 lung transplant recipients were reviewed to identify patients with recurrent primary disease. Their CT scans and pathologic specimens were reviewed.

RESULTS

The frequency of disease recurrence in the six transplantation centers was 1% (15 of 1,394 patients), including six previously reported cases. Sarcoidosis recurred in nine (35%) of 26 transplants and was the most common disease to recur. Three (33%) of nine patients with recurrent sarcoidosis had correlative findings at CT. When present, CT findings were usually different at recurrence compared with pretransplantation CT findings.

CONCLUSION

A relatively small percentage of patients are at risk for recurrence of primary disease following lung transplantation. Sarcoidosis is the most common disease to recur.

High levels of exhaled nitric oxide (NO) and NO synthase III expression in lesional smooth muscle in lymphangioleiomyomatosis

Smooth-muscle proliferation is the hallmark of lymphangioleiomyomatosis (LAM). Although little is known about the pathogenesis of LAM, nitric oxide (NO) is a key regulator of smooth-muscle proliferation. NO is linked to the pathogenesis of other lung diseases such as asthma, in part by the finding of higher-than-normal levels of exhaled NO. If NO were involved in the abnormal smooth-muscle proliferation in LAM, we reasoned that exhaled NO from individuals with LAM would also differ from that of healthy control subjects. To evaluate this hypothesis, we studied exhaled NO in individuals with LAM in comparison with healthy and asthmatic women using a chemiluminescent NO analyzer. Women with LAM had higher exhaled NO than did healthy women but lower than asthmatic women (NO [parts per billion] median (25 to 75%): LAM 8 [7 to 15] [n = 28], control 6 [5 to 8] [n = 21], asthma 14 [8 to 25] [n = 22]; Kruskal-Wallis P < 0.001). Immunohistochemical studies on formalin-fixed, paraffin-embedded sections of surgical and autopsy material from lungs of individuals with LAM showed diffuse NO synthase III (NOSIII) expression in the lesional smooth muscle of LAM similar to that in the vascular endothelium. NOSIII expression was limited to the vascular endothelium and bronchial smooth muscle in healthy control lungs. The increased NO and the presence of NOSIII expression in lesional smooth muscle warrants further study into the potential role for NO in the pathogenesis of LAM.

The spectrum of mutations in TSC1 and TSC2 in women with tuberous sclerosis and lymphangiomyomatosis

Lymphangiomyomatosis (LAM) is a progressive and often fatal interstitial lung disease characterized by a diffuse proliferation of abnormal smooth muscle cells in the lungs. LAM is of unusual interest biologically because it affects almost exclusively young women. LAM can occur as an isolated disorder (sporadic LAM) or in association with tuberous sclerosis complex (TSC). Because only a minority of women with TSC develops symptomatic LAM, we hypothesized that a relationship might exist between the type of germline TSC1 or TSC2 gene mutation and the risk of developing LAM. We examined all 41 exons of the TSC2 gene and 21 coding exons of the TSC1 gene for mutations in a group of 14 women with both TSC and LAM using single-strand conformation polymorphism analysis. Seven mutations were found in TSC2 and one in TSC1. Of the seven patients with TSC2 mutations, two had the same in-frame exon 40 deletion and one had an exon 41 missense change. We conclude that germline mutations in the extreme carboxy-terminus of tuberin can result in LAM. Further studies will be required to determine whether mutations in exons 40 and 41 are associated with an increased incidence and/or severity of LAM in women with TSC.

Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM), a rare disorder of unknown cause that occurs almost exclusively in women of childbearing years, is characterized microscopically by abnormal smooth muscle proliferation in the lung, lymphatics, and mediastinal, abdominal and lower cervical lymph nodes. LAM is associated with progressive dyspnea, recurrent pneumothoraces, chylous effusions, abdominal tumors (angiomyolipoma), and chylous ascites. Because of the predilection of this disease for young women, therapies to date have mainly involved hormonal manipulation. Although the efficacy of these therapies has not been established, the clinical course is more favorable in recent studies compared with earlier reports.