lymphangioleiomyoma
Introduction
Introduction to lymphangioleiomyoma Lymphatic leiomyomas (LAM) is an unexplained cause of progressive systemic disease due to abnormal proliferation of smooth muscles leading to obstruction of the bronchi, lymphatic vessels and small blood vessels. The lungs are the most susceptible, often manifested as diffuse interstitial lung disease, so often referred to as LAM is lymphangioleiomyoma. The disease mainly occurs in menopausal women, clinically often have dyspnea, spontaneous pneumothorax, chylothorax and other manifestations, typical chest imaging can be seen in the diffuse distribution of thin-walled small cysts. There is no satisfactory treatment for this disease. Glucocorticoids and cytotoxic agents are ineffective. Angong progesterone 400mg per month or 400mg every 2 months, or 10~20mg daily, but the effect is not satisfactory. Tamoxifen and progesterone hormone releasing hormone have also been used in the treatment of this disease, but the effect is not certain. The treatment with oophorectomy combined with progesterone has a positive effect compared with single treatment. basic knowledge The proportion of illness: 0.001% Susceptible population: menopausal women Mode of infection: non-infectious Complications: respiratory failure
Cause
Causes of lymphangioleiomyoma
Endocrine factors (75%)
The cause of LAM is unknown, and many facts suggest that the disease may have a relationship with estrogen. This disease does not occur before menarche, and is rare after menopause. There are also a few cases of postmenopausal cases with a history of estrogen supplementation. The disease is aggravated during pregnancy, and is relieved after oophorectomy. In cases of tuberous sclerosis with pulmonary lesions, women have a clear advantage, and living tissues have also confirmed estrogen and progesterone receptors.
However, anti-estrogen treatment, such as resection of bilateral ovaries, radiation therapy, progesterone and other treatments, the results are not satisfactory, indicating that the pathogenesis of lymphangioleiomyomatosis is related to estrogen, there are other important factors involved. .
The cause of pulmonary cyst formation and similar emphysema caused by pulmonary interstitial smooth muscle hyperplasia is still unclear. Some scholars believe that it is caused by smooth muscle compression and conduction of airway, but it is controversial. It is also believed that the formation of "ball-valve" obstruction in smooth muscle hyperplasia in the airway is the main cause of terminal air cavity expansion. The imbalance of the elastin/1-antitrypsin system, leading to the degeneration of elastic fibers, may be the main cause of changes in lung cysts and emphysema.
Prevention
Lymphatic leiomyoma prevention
Temporary lack of effective preventive measures, such as young women with spontaneous pneumothorax or chylothorax should be highly valued, I or family with tuberous sclerosis or renal angiomyolipoma patients, to do a good job of related checks, early detection, Early treatment.
Complication
Lymphatic leiomyomas complications Complications, respiratory failure, chylothorax
The prognosis of this disease is poor. Most patients have progressive pulmonary dysfunction within 1-2 years after diagnosis, and eventually die of respiratory failure.
The imaging findings of lymphangioleiomyoma and histiocytosis syndrome X are similar. The former is more common in women of childbearing age, often accompanied by chylothorax.
Symptom
Lymphatic leiomyomas symptoms Common symptoms Breathing difficulties Chest pain Dry cough chyme chest pericardial effusion chyle sputum with bloodshot
1. Difficulty breathing with slow breathing is the main symptom of LAM.
2. Repeated spontaneous pneumothorax, which can be manifested as unilateral and bilateral, has been reported in the literature, about 95% of patients with spontaneous pneumothorax as the first symptom.
3. Dry cough, less common chest pain, chest chyle exudation, bloody and wheezing in the sputum.
4. Extrapulmonary symptoms include chyluria, chyle pericardial effusion, and chyle ascites.
5. Others: In some patients, uterine fibroids or renal angiomyolipoma can be found, and lung function changes: often obstructive ventilatory dysfunction and diffuse dysfunction.
Examine
Examination of lymphangioleiomyoma
CT
The two lungs are evenly distributed, with a clear circular or polygonal thin wall with a uniform boundary, and the edges are clear. The normal pulmonary lobular structure is submerged by the cystic cavity. Most of the cysts are several millimeters to 5 cm in size, often about 1 cm, and the wall thickness is thin. Uniform, no obvious interstitial fibrosis and nodular shadow, may have mediastinal lymphadenopathy, can be accompanied by pneumothorax, chylothorax, evenly distributed in the lung parenchyma, no tendency to occur in the peripheral lung, smooth wall, The density is slightly higher.
Chest X-ray
The chest radiographs of patients with lymphatic leiomyoma have a large difference, and there is no obvious abnormality in the early stage, or it appears as a ground glass shadow. As the disease progresses, diffuse small nodules appear gradually, from miliary to medium-sized nodular or reticular nodules, with irregular netting and line-like shadows, and more uniform distribution. These shadows may be caused by smooth muscles with multiple cystic hyperplasia. Early lung volume is normal. A small amount of cystic changes can be seen in the lung field as the disease progresses. The chest radiograph can only be displayed when the diameter of the cyst is >1cm. A large number of pulmonary cysts can significantly increase the lung volume, similar to emphysema, and lymphatic obstruction can form the Keley B line. At the same time, unilateral or bilateral pleural fluid can be seen, often chyle, with a large amount and repeated occurrence. Chylous pleural effusion can also occur in the case of unaffected lungs, the incidence of spontaneous pneumothorax is high, lymphangiography can be found in the posterior wall of the abdomen.
Chest CT and HRCT
It is an important means of diagnosing lymphangioleiomyoma. Chest CT, especially HRCT, can clearly show that the common chest radiograph shows unclear lung cysts. Pulmonary cysts of lymphatic leiomyoma have prominent features, which are thin-walled cysts of varying sizes distributed throughout the lung, ranging from 0.5 to 5 cm in diameter, and the thickness of the cyst wall is generally <2 mm. The early cysts are small, and the cysts increase with the development of the disease. The incidence of cysts of this type is 100%, which is an important basis for the diagnosis of lymphangioleiomyoma. In the early days, about 50% of patients developed ground glass. On the CT, only 5% of the nodule shadows can be seen, which is caused by the swelling of the cysts surrounding the overgrown smooth muscle cells. If a flaky shadow appears, it indicates bleeding. Four of the 8 LAM patients reported by Sherrier et al. found mediastinal lymphadenopathy. Quantitative measurement of cyst area by HRCT is consistent with the determination of lung volume, diffusion function, and disease severity as assessed by exercise testing, so HRCT can be used for diagnosis and prognosis. CT or HRCT can detect lesions in the posterior wall of the abdomen, abdominal cavity, kidney, and pelvis.
Pulmonary function tests
LAM is one of the few cases of interstitial lung disease with reticular nodules, increased lung volume, and obstructive or mixed ventilatory dysfunction. LAM lung function showed an increase in total lung volume (TLC), increased residual gas (RV) and RV/TLC, common airflow limitation, first-second forced breathing (FEV1) and vital capacity, FEV1/FVC decreased. The mechanical mechanism of the lungs is characterized by a decrease in the average elastic retractive force and an increase in the upstream resistance. Loss of elastic recoil and increased lung resistance can cause airflow limitation.
LAM often exhibits gas exchange anomalies, the diffusion function (Dlco) is significantly reduced, and PA-aO2 is increased. Most patients have reduced exercise, reduced oxygen consumption, and reduced anaerobic domains. Exercise causes increased respiratory rate, increased ventilation per minute, and reduced respiratory reserve. Exercise limitations also have a significant impact on athletic performance. Due to airflow limitation (decreased ventilation) and pulmonary vascular dysfunction or destruction, many LAM patients have severely impaired exercise capacity.
Diagnosis
Diagnosis and diagnosis of lymphangioleiomyoma
Diagnostic criteria
Mainly from clinical manifestations (women of childbearing age, repeated episodes of pneumothorax, LAM often accompanied by abdominal changes) + saccular features (same size, no sac outside the capsule, no arteries in the sac, normal lungs in the sac, thin wall, more uniform distribution ) + less interstitial fibrosis showing lymphangioleiomyoma.
Differential diagnosis
(1) Fibrous alveolitis and fibrosis at the end of the period (honeycomb lung): its cystic air cavity diameter is 1mm~2.5mm, the distribution is irregular, the wall is thick and accompanied by irregular interlobular thickening, in addition There is a reduction in lung volume, branch expansion and structural deformation, and significant changes in the peripheral pleural.
(2) Neurofibromatosis: The cystic air cavity is also seen in this disease, but its distribution is different from that of LAM. The cystic cavity is located at the tip of the lung with enhanced basal line texture.
(3) Bronchiectasis: The cystic cavity is distributed along the bronchus, and the wall is thick, often with liquid level, and the saccular shadow is rare around the lung, which is enough to distinguish it from LAM.
(4) Lung histiocytosis X: Similar to LAM, but there are multiple nodules at the same time as saccular shadows, no cavities in the nodules, nodular, interstitial changes in the interstitial, nodules and cystoids. The lesions are mostly located on the upper lobe of both lungs, without chylothorax.
(5) Emphysema: similar to LAM, it is difficult to identify. However, emphysema lacks interlobular septal thickening, and residual lobular structure can be seen in the center of most vesicular low-density areas. Central lobular arteries can be seen in low-density shadows; while LAM sacs are uniform in size, evenly distributed, with clear and uniform thin walls. The vascular shadow is located outside the edge of the capsular shadow, and generally has no extraordinary cyst (similar to a large alveolar change). Combined with clinical history, age, gender can help identify.
(6) Tuberous sclerosis: It is a systemic disease. When it invades the lungs, it has similarities in pathology with LAM. It has been reported in the literature that it can coexist with LAM, and some people think that LAM is a frustrating type of tuberous sclerosis. The clinical manifestations of the lungs are similar, but some authors believe that there are two different diseases, but they are indistinguishable from imaging. The tuberous sclerosis mainly involves vascular smooth muscle and rarely invades the lymphatic vessels and lymph nodes. Therefore, the chyle The chest is rare. In addition, the disease has a genetic predisposition, and multiple extrapulmonary lesions outside the lungs.
