Postpartum Bilateral Tension Pneumothoraces

We report the first case report of postpartum bilateral tension pneumothoraces. A 31-year-old primigravida presented with obstructive shock and respiratory failure five days following a normal spontaneous vaginal delivery. Bilateral surgical chest drains were inserted and following computed tomography suggestive of an underlying interstitial lung disease she was transferred to a tertiary cardiothoracic centre. Video-assisted thoracic surgery was carried out with left apicectomy and parietal pleurectomy. Histopathology supported a diagnosis of pulmonary lymphangioleiomyomatosis. We discuss the pathophysiology of labour-induced barotrauma and examine pertinent elements of the acute management of this case.

Isolated Cystic Lung Disease: An Algorithmic Approach to Distinguishing Birt-Hogg-Dubé Syndrome, Lymphangioleiomyomatosis, and Lymphocytic Interstitial Pneumonia

OBJECTIVE. Birt-Hogg-Dubé (BHD) syndrome, lymphangioleiomyomatosis (LAM), and lymphocytic interstitial pneumonia (LIP) frequently present as isolated cystic lung disease and can be challenging to distinguish. If imaging findings are otherwise unremarkable, the radiologist is unaided by ancillary CT findings in narrowing the diagnosis. We hypothesized that the distribution and morphologic features of lung cysts could be used to differentiate BHD syndrome, LAM, and LIP. Therefore, the purpose of this study was to characterize the CT appearances of these conditions and create a practical CT-based algorithm to differentiate among them. MATERIALS AND METHODS. The study was a retrospective review of the CT images of 16 patients with BHD syndrome, 17 patients with LAM, and 14 patients with LIP. On the basis of the data collected, a CT-based algorithm was created, and the CT images were reviewed again. RESULTS. Lower lung-predominant cysts were significantly more likely to be found in patients with BHD syndrome (100% of patients) or LIP (71-93% of patients) than in patients with LAM (6-12% of patients), who were more likely to have diffuse cysts. Compared with patients with LIP or LAM, patients with BHD syndrome were significantly more likely to have elliptical (floppy) paramediastinal cysts (88-94% of patients with BHD syndrome, 36-43% of patients with LIP, and 6-12% of patients with LAM) or a disproportionate number of paramediastinal cysts (69-88% of patients with BHD syndrome, 0-14% of patients with LIP, and 0-6% of patients with LAM). Our algorithm enabled differentiation of BHD syndrome, LAM, and LIP with a high level of accuracy and high interreader agreement (κ = 0.809). CONCLUSION. Radiologists can use the proposed CT-based algorithm to prospectively and confidently suggest one of these disorders as the favored diagnosis. Of importance, this will allow diagnosing the disorder early and accurately, screening for comorbidities, and prevention of potential complications.

Circulating Lymphangioleiomyomatosis Tumor Cells With Loss of Heterozygosity in the TSC2 Gene Show Increased Aldehyde Dehydrogenase Activity

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a destructive metastasizing neoplasm of the lung characterized by proliferation of LAM cells in specialized lung nodules. LAM cells are characterized by expression of the prometastatic and cancer-initiating hyaluronan receptor CD44v6, and loss of heterozygosity (LOH) of TSC1 and TSC2. The circulating neoplastic LAM cells are thought to be involved in metastasis. Because LAM cells display properties of neoplastic, metastatic, and stem cell-like cancer cells, we hypothesized that elevated aldehyde dehydrogenase (ALDH) activity, characteristic of cancer and stem cells, is a property of LAM cells.

METHODS

We performed an in silico search of ALDH genes in microdissected LAM lung nodules. To identify circulating LAM cells, we osmotically removed red blood cells from whole blood to obtain peripheral blood mononuclear cells, which were then sorted by fluorescence-activated cell sorting based on their level of ALDH activity.

RESULTS

Microdissected LAM lung nodules possess a distinctive ALDH gene profile. The cell subpopulation with high ALDH activity, isolated from circulating cells, possessed TSC2 LOH in 8 of 14 patients with LAM. Approximately 60% of the circulating cells with high ALDH activity expressed CD44v6. Cells with TSC2 LOH from patients with LAM and LAM/TSC exhibited different properties in different body locations, but all cell types showed high ALDH activity.

CONCLUSIONS

This new procedure allows for isolation of circulating LAM cells from cultured cells, blood, and chylous effusions and shows that circulating LAM cells are heterogeneous with neoplastic, metastatic, and cancer-stem cell-like properties.

Successful Sirolimus Treatment of Lymphangioleiomyomatosis in a Hepatitis B Virus Carrier

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

Coexistent sarcoidosis and lymphangioleiomyomatosis in a patient with cystic lung disease

A 45-year-old lady presented acutely with pleuritic chest pain, haemoptysis, and dyspnoea. Her background was significant for a 1.4 cm renal angiomyolipoma, and she was an ex-smoker without any relevant family history. A computed tomography (CT) pulmonary angiogram was negative for a pulmonary embolism but demonstrated diffuse cystic change throughout both lungs. A bronchoscopy confirmed a normal endobronchial tree, and pulmonary function tests demonstrated moderate airways obstruction, with reversibility and a normal diffusion capacity for carbon monoxide (DLCO). A video-assisted thoracoscopic surgery (VATS) lung biopsy showed non-caseating granulomas, and serum angiotensin converting enzyme (ACE) was elevated consistent with a diagnosis of pulmonary sarcoidosis. Further sectioning indicated focal areas that stained positive for Human Melanoma Black 45 (HMB-45), confirming lymphangioleiomyomatosis (LAM). A diagnosis of cystic lung disease secondary to coexistent sarcoidosis and LAM was made.

Clinicopathological analysis of clinically occult extrapulmonary lymphangioleiomyomatosis in intra-pelvic and para-aortic lymph nodes associated with pelvic malignant tumors: A study of nine patients

The clinicopathological and immunohistochemical characteristics of clinically occult extrapulmonary lymphangioleiomyomatosis in lymph nodes (LN-LAM) being dissected during surgical staging of pelvic malignancy have not been well investigated. We assessed samples from nine female patients (median age, 61). None had past or familial history of tuberous sclerosis and had LAM lesions other than LN such as lung. The primary malignancies included four endometrial endometrioid carcinomas, one endometrial carcinosarcoma, three ovarian serous carcinomas and one urothelial carcinoma. Median follow-up was 43 months. The number of affected LNs ranged from 1 to 15 (median, 2) with sizes ranging from 1 to 13 mm (median, 3.0). Six cases had clinically occult LN-LAM only within the pelvic LNs, two only within para-aortic LNs, and one within both pelvic and para-aortic lymph nodes. Immunohistochemically, LAM cells exhibited a strong diffuse positivity for β-catenin and E-cadherin in all nine cases. Clinically occult LN-LAM mainly affects peri- or post-menopausal women. On rare occasions, occult LN-LAM may manifest as systemic LAM, including in the lung. β-catenin and E-cadherin carry potential utility as additional diagnostic markers.

Differentiation Between Lymphangioleiomyomatosis and Birt-Hogg-Dubé Syndrome: Analysis of Pulmonary Cysts on CT Images

OBJECTIVE

The purposes of this study were to identify diagnostic imaging markers for differentiating pulmonary cysts in lymphangioleiomyomatosis and Birt-Hogg-Dubé syndrome and to identify potential risk factors for spontaneous pneumothorax in the two diseases.

MATERIALS AND METHODS

This retrospective study included 44 patients with lymphangioleiomyomatosis (44 women; mean age, 35 ± 10.9 years) and 13 patients with Birt-Hogg-Dubé syndrome (nine men, four women; mean age, 45.1 ± 10.9 years). CT findings were analyzed to determine the shape; presence of septation, wall visibility, and subpleural cysts; size; number; distribution; location of the largest cyst; and presence of cysts encircling the bronchovascular bundle ("air-cuff" sign) and of mediastinal fat indentation. Multiple logistic regression was performed to identify risk factors for spontaneous pneumothorax.

RESULTS

Compared with patients with lymphangioleiomyomatosis, patients with Birt-Hogg-Dubé syndrome were significantly older, and more of them were men. The cysts in these patients had a more irregular shape, more septation, lower and more peripheral distribution, larger maximum size, and more attachment to the pleura, air-cuff sign, indentation on mediastinal fat, and subpleural cysts larger than 2 cm. The maximum diameter of cysts was the sole independent risk factor for spontaneous pneumothorax (p = 0.027; 95% CI, 1.043-1.992) in both diseases. ROC analysis showed an AUC of 0.745 (95% CI, 0.612-0.851), and the optimal cutoff value was 22 mm (sensitivity, 72.5%; specificity, 76.5%).

CONCLUSION

Several CT imaging markers may help in differentiating pulmonary cysts in patients with lymphangioleiomyomatosis and those with Birt-Hogg-Dubé syndrome and in predicting spontaneous pneumothorax.

Lymphangioleiomyomatosis: A Case Report and Review of Literature

Pulmonary lymphangioleiomyomatosis (LAM) is a disease, which is most commonly seen in women of childbearing age. The objective of this article was to provide education about the typical clinical presentation, radiologic findings, histology, treatment approaches, and differential diagnosis. Pulmonary LAM is a cystic lung disease, usually generalized and progressive and extremely difficult to treat and is considered to have a poor prognosis. Patients with LAM often present with an insidious onset of dyspnea; this could be secondary to pneumothorax. However, it could also be present as chylothorax and hemoptysis. We discussed a case who presented with chest pain and shortness of breath due to pneumothorax and retrospectively diagnosed with LAM.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Low-dose sirolimus in retroperitoneal lymphangioleiomyomas

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

A case of uterine lymphangioleiomyomatosis in a young woman that was identified via peritonitis

Although lymphangioleiomyomatosis is often observed with tuberous sclerosis, uterine lymphangioleiomyomatosis is rare. Our patient was 36 years old (gravida 0, para 0). She had a history of tuberous sclerosis, and many myometrial cystic lesions were identified during assisted reproductive therapy. Although we administered a gonadotropin-releasing hormone analog, myometrial cystic lesions increased in size. Therefore, simple hysterectomy, bilateral salpingo-oophorectomy and pelvic lymph node biopsy were performed. Postoperative histology showed lymphangioleiomyomatosis and myometrial abscess. For uterine lesions in young women with tuberous sclerosis, the possibility of uterine lymphangioleiomyomatosis should also be considered.

Chest CT Scan at Radiation Dose of a Posteroanterior and Lateral Chest Radiograph Series: A Proof of Principle in Lymphangioleiomyomatosis

BACKGROUND

Given the rising utilization of medical imaging and the risks of radiation, there is increased interest in reducing radiation exposure. The objective of this study was to evaluate, as a proof of principle, CT scans performed at radiation doses equivalent to that of a posteroanterior and lateral chest radiograph series in the cystic lung disease lymphangioleiomyomatosis (LAM).

METHODS

From November 2016 to May 2018, 105 consecutive subjects with LAM received chest CT scans at standard and ultra-low radiation doses. Standard and ultra-low-dose images, respectively, were reconstructed with routine iterative and newer model-based iterative reconstruction. LAM severity can be quantified as cyst score (percentage of lung occupied by cysts), an ideal benchmark for validating CT scans performed at a reduced dose compared with a standard dose. Cyst scores were quantified using semi-automated software and evaluated by linear correlation and Bland-Altman analysis.

RESULTS

Overall, ultra-low-dose CT scans represented a 96% dose reduction, with a median dose equivalent to 1 vs 22 posteroanterior and lateral chest radiograph series (0.14 mSv; 5th-95th percentile, 0.10-0.20 vs standard dose 3.4 mSv; 5th-95th percentile, 1.5-7.4; P < .0001). The mean difference in cyst scores between ultra-low- and standard-dose CT scans was 1.1% ± 2.0%, with a relative difference in cyst score of 11%. Linear correlation coefficient was excellent at 0.97 (P < .0001).

CONCLUSIONS

In LAM chest CT scan at substantial radiation reduction to doses equivalent to that of a posteroanterior and lateral chest radiograph series provides cyst score quantification similar to that of standard-dose CT scan.

TRIAL REGISTRY

ClinicalTrials.gov; Nos.: NCT00001465 and NCT00001532; URL: www.clinicaltrials.gov.

Lymphangioleiomyomatosis: a case report and review of diagnosis and treatment

Lymphangioleiomyomatosis (LAM) is a rare disease that generally affects young women and involves the abnormal proliferation of smooth muscle-like cells (LAM cells) in the lungs (pulmonary LAM) and extrapulmonary sites (extrapulmonary LAM). This disease is rare in males. It is hard to distinguish between lung cancer and pulmonary LAM, especially during early stages. Herein, we present a case of a 66-year-old man with a small nodule in the right upper lobe that was first diagnosed as a lung malignancy using a chest CT scan. After a wedge dissection, a pathologist performed a histologic and immunohistochemical examination, and a diagnosis of pulmonary LAM was made. We further performed a 518-gene panel analysis using next-generation sequencing, and only three genes, BARD1, BLM, and BRCA2, were found to have mutations. We also provide a summary of the diagnosis and treatment of this disease.

Pulmonary manifestations in tuberous sclerosis complex

Tuberous sclerosis complex has manifestations in many organ systems, including brain, heart, kidney, skin, and lung. The primary manifestations in the lung are lymphangioleiomyomatosis (LAM) and multifocal micronodular pneumocyte hyperplasia (MMPH). LAM affects almost exclusively women, and causes cystic lung destruction, pneumothorax, and chylous pleural effusions. LAM can lead to dyspnea, oxygen dependence, and respiratory failure, with more rapid disease progression during the premenopausal years. In contrast, MMPH affects men and women equally, causing small nodular pulmonary deposits of type II pneumocytes that rarely progress to symptomatic disease. Here, we review the clinical features and pathogenesis of LAM and MMPH.

The Lymphangioleiomyomatosis Lung Cell and Its Human Cell Models

Lymphangioleiomyomatosis (LAM) is a multisystem disease of women, affecting lungs, kidneys, and lymphatics. It is caused by the proliferation of abnormal smooth muscle-like LAM cells, with mutations and loss of heterozygosity in the TSC1 or, more frequently, TSC2 genes. Isolated pulmonary LAM cells have been difficult to maintain in culture, and most studies of LAM lung cells involve mixtures of TSC2 wild-type and TSC2-null cells. A clonal population of LAM lung cells has not been established, making analysis of the cells challenging. Cell lines have been established from angiomyolipomas, a common manifestation of LAM, and from tumors from patients with TSC. Circulating LAM cells have also been isolated from blood and other body fluids. LAM cells may also be identified in clusters apparently derived from lymphatic vessels. Genetics, patterns of antigen expression, and signaling pathways have been studied in LAM lung tissue and in LAM cell models, although rarely all in the same study. We show here that LAM cells manifest differences in these characteristics, depending on the source investigated, suggesting further studies.

Characterization of lymphangioleiomyomatosis patients with discordance between spirometric and diffusion measurements of pulmonary function

Background: A subset of lymphangioleiomyomatosis (LAM) patients present with normal FEV1 and FVC but with reduced DLCO. Patients with an isolated reduction in DLCO in other diseases appear to be at higher risk for pulmonary hypertension and worse survival but this has not been previously described in LAM patients. Objective: To characterize the prevalence and clinical progression of LAM patients who present with discordantly low DLCO. Methods: This was a retrospective cohort study of LAM patients in two centers in the United States and Brazil. Discordant DLCO was defined as FEV1 >80% predicted, FVC >80% predicted, and DLCO<80% predicted. We compared the rate of decline in pulmonary function, pulmonary artery to aorta (PA-A) ratio, and VEGF-D levels in patients with concordant and discordant DLCO. Results: The overall prevalence of discordant DLCO was 26.0%. Patients with discordant DLCO did not have a higher rate of yearly decline in FEV1 (-1.0±0.6 vs -1.0±0.6, p=0.50), FVC (-1.0±0.7 vs -0.3±0.8, p=0.54), or DLCO (-2.2±0.9 vs -1.6±0.6, p=0.79). They did not have higher rates of PA-A ratio>1 (23.3% vs 20.1%, p=1.00). Patients with discordant DLCO did not have higher levels of VEGF-D (1214±1256 pg/mL vs 1706±1214 pg/mL, p=0.07). Conclusions: LAM patients who present with a discordantly low DLCO do not appear to have different rates of decline in pulmonary function. Additional biological and radiographic markers are needed to more fully characterize this population. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 206-212).

Pulmonary lymphangioleiomyomatosis associated with aggressive renal angiomyolipoma

Lymphangioleiomyomatosis (LAM) is a rare cystic pulmonary disease that may occur in association with mutations in the tuberous sclerosis genes or arise sporadically. The histologic hallmark of the disease is the "LAM" cell, a spindled to epithelioid smooth muscle-like cell that bears morphologic and immunohistochemical resemblance to the perivascular epithelioid cell tumors (PEComas). The origin of the "LAM" cell is unknown; emerging theories suggest that a member of the PEComa family, the renal angiomyolipoma, may be the primary source and that both LAM and angiomyolipomas are associated with the genetic syndrome tuberous sclerosis. We present a young woman with LAM with an aggressive renal angiomyolipoma confirmed at autopsy.

Clinical characteristics in lymphangioleiomyomatosis-related pulmonary hypertension: an observation on 50 patients

Lymphangioleiomyomatosis (LAM) is a rare diffuse cystic lung disease. Knowledge on LAM-related pulmonary hypertension (PH) is limited. This study aimed to analyze the clinical characteristics of LAM with elevated pulmonary artery pressure (PAP) and evaluate the potential efficacy of sirolimus. The study involved 50 LAM patients who underwent echocardiography. According to the tricuspid regurgitation velocity (TRV), these patients were divided into the TRV ⩽ 2.8 m/s group and TRV > 2.8 m/s group. Both groups comprised 25 females with an average age of 38.6 ± 8.1 and 41.5 ± 8.9 years. In the TRV > 2.8 m/s group, the estimated systolic PAP (SPAP) was significantly elevated (52.08 ± 12.45 mmHg vs. 30.24 ± 5.25 mmHg, P < 0.01). Linear analysis showed that SPAP was correlated with forced expiratory volume in 1 s (FEV₁), diffusing capacity of the lungs for carbon monoxide, alveolar arterial oxygen gradient (P_A-aO₂), and 6 min walking distance (r =-0.392, -0.351, 0.450, and -0.591, respectively; P < 0.05), in which P_A-aO₂ was a risk factor for SPAP elevation (β = 0.064, OR = 1.066, P < 0.05). Moreover, in 10 patients who received sirolimus therapy, SPAP decreased from 57.0 12.6 mmHg to 35.2 ± 11.1 mmHg. The study showed that LAM patients with PH exhibit poor pulmonary function and hypoxemia and may benefit from sirolimus treatment.

Oncogenic effects of urotensin-II in cells lacking tuberous sclerosis complex-2

Lymphangioleiomyomatosis (LAM) is a destructive lung disease that can arise sporadically or in adults suffering from the tumor syndrome tuberous sclerosis complex (TSC). Microscopic tumors ('LAM nodules') in the lung interstitium arise from lymphatic invasion and metastasis. These consist of smooth muscle-like cells (LAM cells) that exhibit markers of neural crest differentiation and loss of the tumor suppressor protein 'tuberous sclerosis complex-2' (TSC2). Consistent with a neural phenotype, expression of the neuropeptide urotensin-II and its receptor was detected in LAM nodules. We hypothesized that loss of TSC2 sensitizes cells to the oncogenic effects of urotensin-II. TSC2-deficient Eker rat uterine leiomyoma ELT3 cells were stably transfected with empty vector or plasmid for the expression of TSC2. Urotensin-II increased cell viability and proliferation in TSC2-deficient cells, but not in TSC2-reconstituted cells. When exposed to urotensin-II, TSC2-deficient cells exhibited greater migration, anchorage-independent cell growth, and matrix invasion. The effects of urotensin-II on TSC2-deficient cells were blocked by the urotensin receptor antagonist SB657510, and accompanied by activation of Erk mitogen-activated protein kinase and focal adhesion kinase. Urotensin-II-induced proliferation and migration were reproduced in TSC2-deficient human angiomyolipoma cells, but not in those stably expressing TSC2. In a mouse xenograft model, SB657510 blocked the growth of established ELT3 tumors, reduced the number of circulating tumor cells, and attenuated the production of VEGF-D, a clinical biomarker of LAM. Urotensin receptor antagonists may be selective therapeutic agents for the treatment of LAM or other neural crest-derived neoplasms featuring loss of TSC2 or increased expression of the urotensin receptor.

Insulin growth factor binding protein 2 mediates the progression of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a progressive pulmonary disease that almost exclusively affects women. LAM cells migrate to the lungs, where they cause cystic destruction of lung parenchyma. Mutations in TSC1 or TSC2 lead to the activation of the mammalian target of rapamycin complex-1, a kinase that regulates growth factor-dependent protein translation, cell growth, and metabolism. Insulin-like growth factor binding protein 2 (IGFBP2) binds insulin, IGF1 and IGF2 in circulation, thereby modulating cell survival, migration, and invasion in neoplasms. In this study, we identified that IGFBP2 primarily localized in the nucleus of TSC2-null LAM patient-derived cells in vitro and in vivo. We also showed that nuclear accumulation of IGFBP2 is closely associated with estrogen receptor alpha (ERa) expression. Furthermore, estrogen treatment induced IGFBP2 nuclear translocation in TSC2-null LAM patient-derived cells. Importantly, depletion of IGFBP2 by siRNA reduced cell proliferation, enhanced apoptosis, and decreased migration and invasion of TSC2-null LAM patient-derived cells. More interestingly, depletion of IGFBP2 markedly decreased the phosphorylation of MAPK in LAM patient-derived TSC2-null cells. Collectively, these results suggest that IGFBP2 plays an important role in promoting tumorigenesis, through estrogen and ERalpha signaling pathway. Thus, targeting IGFBP2 may serve as a potential therapeutic strategy for women with LAM and other female gender specific neoplasms.

Sporadic lymphangioleiomyomatosis with multiple atypical features: A case report and literature review

Lymphangioleiomyomatosis (LAM) is a rare, genetically determined, progressive interstitial lung disease, which almost exclusively affects women, especially at the childbearing age. The initial symptoms and radiographic changes in a patient with LAM are always associated with the respiratory system. Here, we present a case of mediastinal and abdominal LAM of a 22-year-old male, where LAM cells are negative for human melanoma black-45 ( HMB-45). The report of this uncharacterized LAM case will make a significant contribution to the realization of LAM associated clinical features, diagnostic approaches, and its afterward treatments.

Mounier-Kuhn Syndrome Mimicking Lymphangioleiomyomatosis

We present the case of a man with Mounier-Kuhn syndrome (MKS), or tracheobronchomegaly, who was referred to the National Institutes of Health Clinical Research Center because of a potential diagnosis of lymphangioleiomyomatosis (LAM), a rare condition in men. The patient was evaluated using ongoing protocols and provided written informed consent. The case demonstrates the presence of chronic inflammation surrounding the dilated airways and histologic changes of the lung parenchyma with emphysematouslike disruption in areas adjacent to the dilated airways. This finding suggests that damage to the lung parenchyma is an ongoing phenomenon in MKS. Moreover, our analysis of CT images indicates similar abnormalities in areas remote from the dilated airways. Finally, because of increased anatomic dead space, calculation of lung diffusion capacity by the single-breath method yielded abnormally low values that required making a correction for the large anatomic dead space, which can be measured by the single-breath nitrogen washout test.

Effect of beta-agonists on LAM progression and treatment

Lymphangioleiomyomatosis (LAM), a rare disease of women, is associated with cystic lung destruction resulting from the proliferation of abnormal smooth muscle-like LAM cells with mutations in the tuberous sclerosis complex (TSC) genes TSC1 and/or TSC2 The mutant genes and encoded proteins are responsible for activation of the mechanistic target of rapamycin (mTOR), which is inhibited by sirolimus (rapamycin), a drug used to treat LAM. Patients who have LAM may also be treated with bronchodilators for asthma-like symptoms due to LAM. We observed stabilization of forced expiratory volume in 1 s over time in patients receiving sirolimus and long-acting beta-agonists with short-acting rescue inhalers compared with patients receiving only sirolimus. Because beta-agonists increase cAMP and PKA activity, we investigated effects of PKA activation on the mTOR pathway. Human skin TSC2^+/- fibroblasts or LAM lung cells incubated short-term with isoproterenol (beta-agonist) showed a sirolimus-independent increase in phosphorylation of S6, a downstream effector of the mTOR pathway, and increased cell growth. Cells incubated long-term with isoproterenol, which may lead to beta-adrenergic receptor desensitization, did not show increased S6 phosphorylation. Inhibition of PKA blocked the isoproterenol effect on S6 phosphorylation. Thus, activation of PKA by beta-agonists increased phospho-S6 independent of mTOR, an effect abrogated by beta-agonist-driven receptor desensitization. In agreement, retrospective clinical data from patients with LAM suggested that a combination of bronchodilators in conjunction with sirolimus may be preferable to sirolimus alone for stabilization of pulmonary function.

Mammalian Target of Rapamycin: A Target for (Lung) Diseases and Aging

The mammalian target of rapamycin (mTOR) signaling pathway has been studied in the context of an impressive number of biological processes and disease states, including major diseases of the lung such as idiopathic pulmonary fibrosis and chronic obstructive pulmonary disease, as well as the rare condition lymphangioleiomyomatosis. The involvement of mTOR in so many disease states (in and out of the lung) raises the question how one signaling pathway can have overlapping but diverse roles seemingly everywhere. Findings in the last decade have placed the mTOR pathway in a new context as an important, conserved mediator of the aging process. This offers one explanation for the pleiotropic effects of mTOR: -that many chronic diseases are also diseases of aging and that pathways modulating aging will have widespread effects on associated disease. However, this may not be the entire story, because mTOR is also implicated in a large number of diseases not linked to aging. In this article, we discuss the current state of knowledge regarding mTOR, especially in the context of lung pathologies, and offer a potential explanation for its widespread involvement in human disease.