CONGENITAL CYSTIC DISEASES OF THE LUNG Dr Aram Baram MD, MRCSEd
CONGENITAL CYSTIC DISEASES OF THE LUNG• This group of entities is characterized by congenitaly cystic pulmonary tissue.• Although the exact embryogenesis of various forms is disputed, all result in aberrant differentiation of bronchi, bronchioles, alveoli, and pulmonary vasculature.• All of these pathologies are causing neonatal respiratory distress• The major forms of congenital cystic lung disease include:1) Pulmonarysequestration, 2) Bronchogenic cyst3)Congenital cystic adenomatoid malformation4) Congenital lobar emphysema.
PULMONARY SEQUESTRATION• Pulmonary sequestration is a condition in which a segment or lobe of lung tissue has no bronchial communication with the normal tracheobronchial tree.• The arterial blood supply is from a systemic vessel.• This vessel often arises from the aorta.• The venous return is usually through the pulmonary veins but may be to the systemic venous system.
Types1)Extralobar sequestration Is separate from the normal lung and has its own visceralpleura. Left side affected in 90% of the cases .Usually found in the posterior costophrenic angle. Repeatedinfections in the lesion may develop if a communication withthe foregut is present.Surgical resection is indicated for symptomatic patients and when the diagnosis is in question.2) Intralobar sequestration is situated within normal lung parenchyma.
Diagnosis• In 50% to 65% of the cases, they are associated with other anomalies, namely congenital diaphragmatic hernia, eventration, esophageal duplications, and tracheoesophageal fistula.• Boy:girl ratio of 3:1.• Children and young adults with recurrent left-lower-lobe pneumonia should be suspected of having an intralobar sequestration.• Postnatal chest radiography could not always identify the lesion, but CT scanning or magnetic resonance imaging (MRI) are diagnostic.• Treatment consists of a lobectomy.• Careful identification of the arterial supply and suture ligation is necessary
BRONCHOGENIC CYSTS• Bronchogenic cysts originate in abnormal diverticuli of the lung bud in the third to sixth week of fetal life.• They are usually located adherent to the left mainstem bronchus or carina and are extrapulmonary in location within the middle mediastinum.• Abnormal budding in the distal tracheobronchial tree causes intraparenchymal cysts.• The cyst wall contains all elements of the normal bronchus: columnar and mucus-secreting epithelium, smooth muscle, elastic tissue, and cartilage.
BRONCHOGENIC CYSTS• Most children with obstructing cysts who present in early infancy have moderate to severe respiratory distress and clinical signs of airway obstruction such as stridor, wheezing, and cyanosis.• Cysts may be air filled, fluid filled, or exhibit air– fluid levels.• An air-filled bronchogenic cyst on a chest radiograph is sharply defined and round.
BRONCHOGENIC CYSTS• The cyst can expand rapidly; if it ruptures, it may produce a tension pneumothorax.• Surgical resection using an open or minimally invasive technique is indicated for all bronchogenic cysts in infants and children.
CONGENITAL CYSTIC ADENOMATOID MALFORMATION• Congenital cystic adenomatoid malformation (CCAM) is a rare form of congenital cystic disease of the lung.• The lesion is caused by an arrested alveolar development associated with a proliferation of terminal bronchioles in the affected lobe.• These bronchioles are lined by columnar or cuboidal epithelium and have soft walls. Air enters and then is trapped, causing cystic dilation of the bronchioles.
CONGENITAL CYSTIC ADENOMATOID MALFORMATION• The entire malformation may cause a mediastinal shift to the opposite side and compressive atelectasis of otherwise normal adjacent lung tissue.• The newborn with a large CCAM presents with severe respiratory distress secondary to the space-occupying mass, compression of the contralateral lung, and the inadequate volume of functioning lung tissue at the time of presentation.• The contralateral lung may also be hypoplastic.
CONGENITAL CYSTIC ADENOMATOID MALFORMATION• Radiographic diagnosis of the mass may be difficult; it may be confused with congenital lobar emphysema (CLE).• Emergency thoracotomy and lobectomy is often lifesaving. In the older child or adult, surgical resection is required to remove the source of recurrent pneumonia.• Resected patients have a good prognosis. Less commonly, patients with CCAM present in childhood with a history of recurrent pulmonary
CONGENITAL LOBAR EMPHYSEMA• Congenital lobar emphysema is a surgically correctable cause of severe respiratory distress in infancy.• Affected infants may present with respiratory distress that is mild or severe, precipitated by crying, feeding, or, on occasion, respiratory infection.• Boys are more often affected than girls. The left upper lobe is most frequently involved, followed by the right middle lobe
CONGENITAL LOBAR EMPHYSEMA• The pathology of CLE has been attributed to deficient bronchial cartilage in the affected main bronchus, which causes endobronchial proliferation of mucous membranes and subsequent obstruction.• Deficient cartilage (25% of cases), endobronchial obstruction (13%), extrinsic compression of the bronchus by an anomalous vessel (1%), and diffuse lobar bronchial abnormalities (4%) have all been demonstrated; no cause has been found in 50% of cases.