Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + • Uncommon aberrations of respiratory tract development-Starts at 4th week of fetal life-Initial phase of airway branching until 16th wk-Canalicular phase: Capillaries develop (16th to 26th wk)-Alveolar phase: 26th wk on, alveolar air sacs form with type I, II pneumocytes• Tracheobronchial atresia (TA)-Can occur at any level-May involve isolated or multiple areas-Diffuse disease is fatal-Isolated bronchial atresia results in bronchus with blind pouch leads to compression of surrounding lung and emphysematous changes-Anomalous tracheal or esophageal bronchi and diverticular are related diseases• Bronchogenic cysts (BC)-Abnormal budding of foregut may result in formation of BC-Commonly occur in pulmonary hilum or mediastinum, occasionally pulmonary parenchyma-Usually single, lined by cuboidal respiratory epithelium, preferentially in lower lobes-Cysts generally thin walled, occasionally with cartilage-May communicate with tracheobronchial tree-Known to enlarge rapidly and rupture causing tension pneumothorax• Bronchopulmonary dysplasia (BPD): Cluster of diseases includes pulmonary agenesis, aplasia, and primary and secondary hypoplasia-Unilateral agenesis occurs when 1 lung and vessels fail to develop-Pulmonary aplasia: Blind bronchial tumor stump exists and soils normal lung with secretions-Pulmonary hypoplasia: Low radial alvelolar count and low lung to body weight ratio without inciting cause-Secondary pulmonary hypoplasia: Occurs due to fetal or maternal abnormalities such as congenital diaphragmatic hernia, oligohydramnios, Potter syndrome, abnormal bone development• Pulmonary sequestration (PS)-Abnormal budding of foregut leading to lung parenchyma without bronchial communication-Can be intralobar (85%) or extralobar-Often have systemic blood supply from abdominal aorta, 96% drain into pulmonary venous system• Cystic adenomatoid malformation (CAM)-Overgrowth of terminal bronchiolar structures lined by respiratory epithelium with disorganized elastic connective tissue and smooth muscle-Solid structures interspersed with cysts resembling immature alveoli• Congenital Lobar Emphysema (LE)-Hypoplastic bronchial cartilage in 25-75% of patients; increased alveoli number in 37% (polyalveoli)-Neonates with prolonged vent support may develop LE from catheter trauma and barotraumas, affecting right lower lobe (RLL) +++ Epidemiology + • BPD: 50% have associated cardiac anomalies• PS: Left lung affected 58% of time• LE: Left upper lobe (LUL) most commonly involved, then right middle lobe (RML) +++ Symptoms and Signs + • Often presents early in life• Some remain occult until adulthood• TA: Neonates present with intractable cyanosis with normal larynx on intubation• Isolated bronchial atresia: Wheezing, stridor, pulmonary infections due to mucocele formation and compression of normal lung• BC: Mediastinal present with airway compression, parenchymal present with pulmonary infection• BPD (agenesis): Neonates present with tachypnea and cyanosis• BPD: Some patients present in childhood; dyspnea and wheezing and tracheal deviation toward side of agenesis• BPD (hypoplasia): Presents in neonates with tachypnea and hypoxemia resistant to oxygen; persistent fetal circulation• PS: Presentation ranges from asymptomatic lower lobe masses to recurrent lower lobe infections due to seeding from pores connected to normal lung, rarely hemoptysis, congestive heart ... Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth