 Cystic Lung Disease
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Cystic lung disease consists of four distinct conditions that may share a degree of common origin during fetal development. These conditions are:
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- Bronchogenic cysts (also called a bronchopulmonary foregut malformation) - a cyst most commonly found on midline chest structures of the body such as the esophagus and trachea, and sometimes found on the lower lobes of the lung. Some of these cysts become symptomatic by becoming infected or enlarging in size to the point where they compromise the function of the adjacent airway.
- Cystic adenomatoid malformation (CCAM) - a benign (non-cancerous) mass of abnormal lung tissue, located usually on one section (lobe) of the lung. See Anatomy of the Respiratory System) This condition is caused by overgrowth of abnormal lung tissue that may form fluid filled cysts or result in the failure of the development of the tiny air sacs that characterize a normal lung. The tissue does not function as normal lung tissue. There are two types of CCAMs. Type I is distinguished by one or more large cysts. Type II has both solid regions and cysts.
- Lobar emphysema - a congenital(develops before birth) or aquired (not present at birth) condition that involves an obstruction in a lobe of lung that causes air flow to become trapped during inflation and expiration of the lungs. A part, but more often all of the lobe may be involved, usually the left upper lobe. The obstruction of air flow causes the lung to distend(stretch out and expand). Depending on the extent of distension, the affected lobe can compress the unaffected lobe below or above it, and/or the opposite lung by extending across the mediastinum (the area that separates the lungs, that houses vital structures such as the heart and major vessels). Without treatment, this condition can cause acute respiratory distress and even circulatory collapse.
- Pulmonary sequestration - a mass of nonfunctioning pulmonary (pertaining to the lungs and respiratory system) tissue. This kind of mass is subdivided into two types: extralobar or intralobar. An extralobar sequestration is typically located just above or just below the diaphragm. It is separated from the lung and enveloped by its own pleura (membrane that covers the outside of the lung) An intralobar sequestration is typically found in the lower lung lobes, more often on the left side, and they are characterized by recurrent pulmonary infections. Sequestrations can interfere with normal circulation, cause respiratory infections and/or lead to heart failure.
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Symptoms can include:
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- Breathing difficulty
- Pain with breathing
- Wheezing
- Shortness of breath
- Recurrent pneumonia
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Symptoms of cystic lung diseases may resemble other conditions or medical problems. Always consult your baby's physician for a diagnosis.
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If your child's physician suspects a cystic lung disease, the following tests may be performed:
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- Prenatal ultrasound
- Chest computerized tomography scan of the lungs (Also called a CT or CAT scan.) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called
- Chest x-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs of the chest onto film.
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Bronchogenic cysts - The condition is usually discovered on a fetal ultrasound or a chest x-ray after the fetus or newborn demonstrates signs and symptoms of airway obstruction.
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CCAM - A CCAM may be a coincidental finding at fetal ultrasound or it may be diagnosed when an ultrasound is done on a fetus in distress. Whether cystic or solid, a CCAM can be life threatening to the fetus, leading to a mediastinal shift, impaired cardiac function, and fetal hydrops (congenital heart failure). Therefore, if the lesion is detected prenatally, close monitoring of the fetus is required.
Lobar emphysema - This condition is usually also discovered on a chest x-ray after a child demonstrates extreme difficulty and pain in breathing. These symptoms usually become apparent right after birth, but may be delayed for as long as 5 to 6 months in some patients. Other patients remain undiagnosed until school age or beyond. If the obstruction is not found on a x-ray, a bronchoscope may be used. For this procedure, the bronchoscope, a lighted tube, is passed down the windpipe so that the bronchial tubes may be examined.
Pulmonary sequestration - Extralobar sequestration is most often found coincidentally during the newborn period because of the discovery of another anomaly such as a diaphragmatic hernia. In contrast, an intralobar sequestration typically is discovered in a somewhat older child who has a lobar pneumonia which does not clear or which leaves a radiographic abnormality even after effective treatment of the infection.
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Specific treatment for cystic lung diseases will be determined by your baby's physician based on:
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- your baby's gestational age, overall health, and medical history
- extent of the disease
- your baby's tolerance for specific medications, procedures, or therapies
- expectations for the course of the disease
- parental opinion or preference
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There are several ways to treat progressing CCAMs. These include: surgical aspiration (fluid suctioning) of a cystic legion, removal of a solid mass or affected lobe during fetal surgery. For regressing lesions that do not produce further symptoms, simple post-natal follow up is needed which will include careful chest imaging and potential delayed pulmonary resection. Though open for debate, the rationale for an eventual elective resection for such a CCAM is the rare but reported incidence of malignant degeneration in such lesions in adults. A CCAM may also produce neonatal respiratory distress complicated by pulmonary hypertension, and such babies may require urgent neonatal operation and/or aggressive management of their acute respiratory failure including the use of extracorporeal membrane oxygenation (ECMO).
For pulmonary sequestration and lobar emphysema, surgery is almost always required to remove the affected lobe (lobectomy) in order to prevent further damage to the entire lung. Bronchoscopic or open surgical treatment, if done promptly is almost always successful, leaving little or no permanent impairment of breathing capability.
Thoracoscopic (minimally invasive) surgical removal of a broncheogenic cyst may be feasible based on the patient's age, symptoms and the location of the cyst. In the face of airway compression careful and controlled open removal of the cyst is mandatory. Concurrent respiratory support may include careful ventilation or even ECMO. Like the indication for a CCAM that doesn't produce symptoms, an asymptomatic bronchogenic cyst should be removed to prevent a long-term complication, infection, bleeding, or malignant degeneration.
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Fortunately, children typically do well after the treatment of their cystic lung disease. If they have severe associated anomalies or if the normal lung development has been compromised, then the outcomes may be more limited.
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