Lung Review

JURNALUL PEDIATRULUI – Year IX, Vol. IX, Nr. 35-36, july-december 2006

CONGENITAL LUNG MALFORMATIONS A REVIEW
VL David1, A Radulescu2, MC Popoiu3 1 Children’s Hospital “Louis Turcanu“– Department of Pediatric Surgery, Timisoara, Romania 2 Children's Hospital Columbus, Department of Pediatric Surgery, Columbus, Ohio, U.S.A 3 University of Medicine and Pharmacy “Victor Babes“ - Department ofPediatric Surgery Timisoara, Romania
Abstract Congenital lung malformations are a group of rare, nonhereditary conditions that can be the source for important morbidity and mortality in infants and children. The histopathologic characteristics, clinical presentation, diagnostic tools and management options of the most important congenital lung malformations are briefly reviewed. The lesionsanalyzed are cystic adenomatoid malformation, pulmonary sequestration, bronchogenic cyst and congenital lobar emphysema. The antenatal diagnosis, by ultrasound scan, permits early recognition and thus adequate management. After birth thoracic computed tomography is the most useful diagnostic tool. Management of the lesions is dictated by the characteristics of the lesion and the clinical status of thepatient. Resection of nearly all, even asymptomatic, congenital lung lesions is advocated. Key words: lung malformations; cystic adenomatoid malformation; bronchopulmonary sequestration; bronchogenic cyst; congenital lobar emphysema; child Introduction Congenital lung malformations occur rarely but could represent an important cause of respiratory distress in the new-born. The most importantcongenital bronchopulmonary malformations include congenital cystic adenomatoid malformation (CCAM), pulmonary sequestration (PS), bronchogenic cysts (BC) and congenital lobar emphysema (CLE). Other malformations are agenesis of the lung or agenesis of a lobe of the lung. Embryology The respiratory system development begins with the evagination of cells from the foregut endoderm into the splanchnicmesenchyme at 3 weeks of gestation (1). The respiratory mucosa derives from the endoderm of the ventral foregut, while the supporting tissue and the vasculature have a mesodermal origin (2). Following the anatomic changes that occur in its architecture lung morphogenesis can be divided into five stages: embryonic, pseudoglandular, canalicular, saccular, and alveolar (1) (fig. 1): 1 Embryonic period(3-7 weeks). At 26 embryonic days in the ventral wall of the foregut a laryngotraheal grove appear (2). Grooves lips fuse at the caudal end and form the tracheal diverticulum. From this diverticulum the two main bronchi buds bulge out. The main bronchi divide into two lobar bronchi on the left and three on the right side, defining the lobar anatomy of the human lung. All lobar airways can be detectedby the sixth gestational week. Development of the pulmonary vasculature uses the primordial airways as a template (3). The human lungs are supplied by two vascular systems, which develop sequentially. First, the pulmonary circulatory system is established after five gestation weeks, and then the bronchial arteries arise from the aorta after a delay of approximately 3 weeks (3). 2 Pseudoglandularperiod (7–17 weeks). The conducting airways continue to branch and bud. The airway conducts expand in the periphery producing a glandular appearance (1). During this period mucous glands, bronchial cartilage, and epithelial airway cells develop (3). By the 16th gestation week the tree of conducting airways has fully developed.

Fig.1 Embriology - From: Jeffrey A. Whitsett, Susan E. Wert andBruce C. Trapnell. Genetic disorders influencing lung formation and function at birth. Human Molecular Genetics, 2004, Vol. 13, Review Issue 2 R207-R215. 46

JURNALUL PEDIATRULUI – Year IX, Vol. IX, Nr. 35-36, july-december 2006 3 Canalicular period (16–26 weeks). Tubules expand to form saccules widening the airway lumina. The mesenchyme thins and the airspaces come into increasingly close...