Introduction:
Congenital lobar overinflation (CLO) is a rare fetal developmental anomaly of the lungs. It is also termed congenital lobar emphysema (CLE), characterized by air entering the lungs, but due to an obstruction in the airways, air cannot leave the lungs, leading to an enlarged, overinflated lung lobe. It is also sometimes associated with congenital heart defects such as ventricular septal defect (abnormal connections between the lower chambers of the heart), patent ductus arteriosus (developmental abnormality of the heart), and tetralogy of Fallot (combination of four heart defects affecting the normal flow of blood through the heart). It is most commonly seen in neonatal or early infancy and rarely seen in adults. It has a male predilection over females with a 3:1 ratio. Babies born with congenital lobar overinflation are safely born with cesarean or C-section, or through natural delivery. They may experience respiratory distress immediately after birth or anytime during childhood.
Each lung is divided into two or three sections, known as lobes. The right lung is divided into three lobes, whereas the left is divided into two lobes only. The left upper lobe is affected mostly by almost 40 percent, followed by the right middle lobe at 34 percent and the right upper lobe at 21 percent. The involvement of the lower lobe is rare and present in only two percent of the cases.
The affected lobe becomes non-functional due to overdistention and air trapping. Due to the severity of the symptoms, it is often diagnosed within the first six months of birth. The overinflated lobes thereby cause impaired ventilation and perfusion. The increased overinflation causes compression of adjacent organs and ultimately causes respiratory failure and death.
What Is the Cause of Congenital Lobar Overinflation?
Congenital lobar overinflation can be due to the following reasons:
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Idiopathic or unknown causes in 50 percent of the cases.
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Absence of bronchial cartilage. Hypoplasia (underdevelopment or incomplete development of organ tissues) or dysplasia (abnormal cell development within tissues and organs).
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Parenchymal diseases (conditions that damage the part of the kidney).
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External bronchial obstruction (upper airway obstruction occurring in mouth and nose).
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Internal bronchial obstruction (lower airway obstruction occurring in airway passages of the lungs and pharynx).
What Is the Histopathology Behind Congenital Lobar Overinflation?
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There is no destruction of the alveolar walls and septum with normal acini, but acinar maturation with age and overinflated alveoli are seen.
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There is no tissue destruction, as seen in the case of emphysema. It has two forms:
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Hypo Alveolar - If the number of alveoli is less than normal.
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Poly Alveolar - If the number of alveoli is more than normal.
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What Are the Types of Congenital Lobar Overinflation?
There are two types of congenital lobar overinflation:
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Intrinsic Congenital Lobar Overinflation: It occurs when there is an obstruction from within or inside the lungs. For example, when bronchial cartilage acts like a single or one-way valve.
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Extrinsic Congenital Lobar Overinflation: It occurs when there is a compression of the airways due to nearby abnormal structures, such as a bronchogenic cyst.
What Are the Signs and Symptoms of Congenital Lobar Overinflation?
The signs and symptoms of congenital lobar overinflation:
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Shortness of breath or dyspnea.
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Rapid breathing or tachypnea.
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Enlarged chest due to overinflation involving at least one lung lobe.
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Cyanosis - bluish discoloration of the skin.
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Wheezing.
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Increased heart rate or tachycardia.
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Respiratory distress.
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Underdevelopment of cartilage that supports the Bronchial tube.
What Are the Diagnostic Tests for Congenital Lobar Emphysema?
The Diagnostic tests include:
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Chest X-ray: The affected lobes show overinflation and hyper lucency with oligemia (reduction in pulmonary blood volume) or lack of vessels. The lateral film may show posterior displacement of the heart. Mass effect with mediastinal shift and hemi-diaphragmatic depression is also seen. A lateral decubitus film with the patient lying on the affected side may show little or no change in the lung volume.
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Computed Tomography (CT) Scan: It is the standard gold method to diagnose congenital lobar emphysema. It attenuates vascular structures in the affected lobe and may also show compressive atelectasis of adjacent lobes. It helps in evaluating the affected lobe from the normal structures. A single photon emission technology combined with a CT scan can be used to evaluate the perfusion ventilation ratio in affected lobes. A CT, along with injectable intravenous contrast, helps to evaluate the vascular anomalies in congenital lobar emphysema.
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Fetal Ultrasound: The lungs of the fetus show hyperechogenicity with or without mediastinal shift.
What Is the Treatment Modality for Congenital Lobar Overinflation?
The severity of the disease defines the treatment modality. Patients with mild to moderate symptoms can be treated conservatively with regular follow-up and observation, whereas lobectomy or surgical removal of the affected lobe is preferred with severe symptoms. The conservative approach has become popular due to antenatal diagnosis and intrauterine regression.
What Are the Differential Diagnosis of Congenital Lobar Overinflation?
The differential diagnosis of congenital lobar overinflation includes:
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Bronchial Atresia - Bronchial atresia is typically seen with obliterated proximal segments of the bronchus associated with hyperinflation of the distal lung. Air trapping can be seen in the parenchyma distal to the atretic segment.
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Pulmonary Hypoplasia - It is characterized by an incomplete development of lung tissues.
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Congenital Pulmonary Airway Malformation (CPAM) - Congenital pulmonary airway malformation and congenital lobar emphysema typically show similar features on ultrasound with high echogenic masses. Also, congenital lobar emphysema has no cystic spaces compared to congenital pulmonary airway malformation.
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Pulmonary Arterial Hypoplasia - It is a rare childhood malformation usually linked with cardiac abnormalities.
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Swyer-James Syndrome - It is a lung disorder that causes a reduction in alveolar hypertension and pulmonary vasculature. Bronchiectasis (thickening and widening of walls of bronchi due to infection and inflammation) may or may not be present.
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Filamin A Mutation - The Filamin A gene produces filamin protein, which helps build the internal network of protein filaments known as the cytoskeleton. The cytoskeleton gives cellular structure and allows them the flexibility to change shape. It leads to skeletal dysplasia, cardiovascular abnormalities, and otopalatodigital spectrum disorders and is also associated with lung diseases.
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Pneumothorax - It is the accumulation of air outside the lung but within the cavity of the lung (pleural cavity).
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Pneumonia - Pneumonia (an infection affecting one or both the lungs) in the affected lungs in chest X-ray shows consolidations, which improve on taking antibiotics. There is no overinflation seen in cases of pneumonia.
What Is the Prognosis of Congenital Lobar Overinflation?
Mild to moderate cases can be managed easily with a conservative approach, whereas severe cases require lobectomy (a surgical procedure to remove one of the lung’s lobes). The prognosis of the disease is excellent, and mortality is quite low.
What Are the Complications for the Congenital Lobar Overinflation?
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Cyanosis.
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Surgical complications.
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Respiratory failure.
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Infantile death.
Conclusion:
To conclude, congenital lobar overinflation is a rare developmental anomaly of the lungs in infants characterized by overinflation of one or more lobes, leading to compression of lung parenchyma and displacement of mediastinal structures. It usually presents with cyanosis (bluish or grayish discoloration of lips, nails, skin, or skin around the eyes), rhonchi (airway sound), wheezing, and difficulty breathing. The diagnosis is made based on the clinical examination and imaging findings. Computed tomography of the lungs is considered the gold standard for diagnosing congenital lobar overinflation. The best treatment for a severe case is lobectomy or lobar resection. The prognosis of the disease is excellent, and mortality is quite low.
