Congenital Pulmonary Lymphangiectasia - About an Unknown Disease Entity

Introduction

Congenital pulmonary lymphangiectasia is a rare condition caused by defects in the development of the pulmonary lymphatic system. The etiology and prevalence of the disease are not known clearly. It is predominantly seen in infants at the time of birth. This condition has a poor prognosis and causes death in infants shortly after birth.

What Is a Lymphatic System?

The lymphatic system is a network of channels (lymph vessels) that drain the lymph (a thin watery fluid) from different areas of the body into the bloodstream. This supports the immune system to protect the body against diseases and infection.

What Is Congenital Pulmonary Lymphangiectasia?

Congenital pulmonary lymphangiectasia is a rare vascular malformation disorder affecting infants causing abnormally widened or dilated lymphatic vessels in the lungs. This disease is characterized by pulmonary subpleural, interlobar, perivascular, and peribronchial lymphatic dilation. The other names of this disease are:

• Pulmonary cystic lymphangiectasia.

• Pulmonary lymphangiomatosis.

What Are the Types of Congenital Pulmonary Lymphangiectasia?

Esther and Barker classified congenital pulmonary lymphangiectasia in 2004 as follows:

1. Primary congenital pulmonary lymphangiectasia.

2. Secondary congenital pulmonary lymphangiectasia.

What Are the Causes of Congenital Pulmonary Lymphangiectasia?

The exact causes of congenital pulmonary lymphangiectasia are unknown. Most commonly it occurs sporadically (for no reason).

Primary pulmonary lymphangiectasia is caused by:

• Congenital defects during the development of the lungs.

• The fetal lung failed to undergo the regression process in the 20th week of gestation.

• Generalized lymphatic dysplasia (widespread lymphedema affecting all parts of the body).

• Other unrelated congenital syndromes (Down syndrome, Turner’s syndrome).

Secondary pulmonary lymphangiectasia is caused by:

• Cardiac anomalies causing pulmonary venous flow obstruction.

• Lymphatic obstruction.

• Acquired by infections.

This disease can also be inherited as dominant, recessive, or X-linked inheritance patterns.

What Are the Signs and Symptoms of Congenital Pulmonary Lymphangiectasia?

Symptoms associated with congenital pulmonary lymphangiectasia develop shortly after birth. In some cases, symptoms develop later. The symptoms are:

• During the intrauterine period, non-immune hydrops fetalis (excessive accumulation of fetal fluid within the body cavity of the baby) along with pleural effusion is linked to congenital pulmonary lymphangiectasia.

• The symptoms develop later in some cases. Affected infants develop respiratory failure, and cyanosis (abnormal bluish discoloration due to poorly oxygenated blood).

• Dyspnea (difficulty in breathing).

• Coughing and wheezing.

• Coughing up blood (hemoptysis).

• Lymphedema (swelling due to accumulation of lymphatic fluids).

• Tachypnea (abnormally rapid breathing rate).

• Chylous pleural effusion is called chylothorax (accumulation of chyle or lymph fluid in the pleural cavity).

• Some infants often develop heart abnormalities.

How to Diagnose Congenital Pulmonary Lymphangiectasia?

The diagnosis of congenital pulmonary lymphangiectasia includes clinical evaluation, family history, and obstetric history. The diagnostic tests for congenital pulmonary lymphangiectasia are:

• High-resolution Helical Chest X-ray - It provides a cross-sectional image of the lungs. It helps to detect fluid accumulation in the chest cavity or lung tissues.

• Obstetric Fetal Ultrasound - Helps to detect hydrops fetalis (which includes placental enlargement, pleural and pericardial effusion), and polyhydramnios.

• Fetal Magnetic Resonance Imaging (MRI) - This test can find lymphatic dilation, pleural effusion, and primary cardiovascular defects in cases of secondary pulmonary lymphangiectasia.

• Post-natal MRI - Detects thickening of the interstitium, pleural effusion, and atelectasis which are the findings of congenital pulmonary lymphangiectasia.

• Lymphangiography - This diagnostic test is used to detect opacification of pleural lymphatics, formation of extrathoracic lymphatic collateral vessels, and presence of any lymphatic leaks.

• Lymphoscintigraphy - This test is used to visualize the lymphatic system to detect lymphedema, poor lymphatic clearance rates, and lymphatic vessel dilation.

• Thoracocentesis - The possible finding of this test is chylothorax (white, odorless, and milky appearance with triglyceride levels of more than 110 mg per deciliter).

• Others - Pulmonary function test, bronchoscopy, pleural effusion test and lung biopsy are other diagnostic tests used for the diagnosis of congenital pulmonary lymphangiectasia.

What Is the Differential Diagnosis for Congenital Pulmonary Lymphangiectasia?

The following disorders show symptoms similar to that of congenital pulmonary lymphangiectasia. The differential diagnosis includes:

1. Lung infections.

2. Interstitial lung disease (disorders that cause scarring of the lungs).

3. Idiopathic interstitial lung pneumonitis (class of diffuse lung disease affecting the airways).

4. Follicular bronchiolitis (development of lymphoid follicles in the walls of small airways).

5. Pulmonary alveolar proteinosis (rare lung disease causing accumulation of surfactant within the lungs).

6. Idiopathic pulmonary hemosiderosis (rare lung disease in children causing recurrent episodes of alveolar bleeding).

7. Lymphangiomatosis (abnormal growth of smooth muscle cells in the lymphatic system of lungs).

All these diseases cause respiratory distress in infants and children.

How to Treat Congenital Pulmonary Lymphangiectasia?

The treatment of congenital pulmonary lymphangiectasia includes:

• Respiratory Support - Intubation and mechanical ventilation for maintenance of respiratory function. High mean airway pressure, high-frequency oscillatory ventilation, and nitric oxide is used for pulmonary hypertension. Patients may require home oxygen and frequent monitoring and treatment for respiratory infections is important for maintaining pulmonary health.

• Pharmaceutical Interventions - Steroids are used in cases of premature delivery to help lung development. Corticosteroids are used to treat inflammatory conditions. Octreotide (long-acting somatostatin analog) is used for the treatment of chylothorax as it suppresses chyle formation.

• Surgical or Invasive Interventions - In case of pleural effusion, placement of a chest tube for drainage is indicated. Thoracocentesis is a diagnostic procedure but it is also used for the management of pleural effusion and to relieve respiratory distress. Pleuroperitoneal shunting is the management option in case large volumes of fluid are to be drained and also for intractable chylothorax. Thoracic duct ligation is the best therapy for chylothorax which involves the ligation of the site of leakage. The process of removal of the parietal pleura from the rib cage is called pleurectomy which is used for the treatment of chylothorax. Pleurodesis (the process of adhering to visceral and parietal pleura by chemical or mechanical methods) is also used for the management of chylothorax.

• Fluid and Nutritional Support - It is important to replace the fluids and electrolytes lost through edema and pleural effusions. Vitamin and nutrition supplementation is also important to replace the fat-soluble vitamins and proteins lost through chylothorax.

What Are the Complications of Congenital Pulmonary Lymphangiectasia?

Chylothorax is common in congenital pulmonary lymphangiectasia. If chylothorax is left untreated after birth it can cause malnutrition, dehydration, weakness, and respiratory failure. Complications such as recurrent cough and wheezing and chronic lung diseases are seen in children with congenital pulmonary lymphangiectasia who survived the neonatal period.

Conclusion

Congenital pulmonary lymphangiectasia is a rare but serious condition. The cause of this disease is unknown. Further research is needed to provide the definitive cause of the disease and to promote treatment options in the future. Recent advances made in neonatal intensive care have reduced the rate of fatal outcomes of pulmonary lymphangiectasia at birth.