Anatomical, histologic, and genetic characteristics of congenital chest wall deformities.

There is a large and diverse group of congenital abnormalities of the thorax that manifest as deformities and/or defects of the anterior chest wall and, depending on the severity and concomitant anomalies, may have cardiopulmonary implications. Pectus excavatum, the most common anterior chest deformity, is characterized by sternal depression with corresponding leftward displacement and rotation of the heart. Pectus carinatum, the second most common, exhibits a variety of chest wall protrusions and very diverse clinical manifestations. The cause of these conditions is thought to be abnormal elongation of the costal cartilages. Collagen, as a major structural component of rib cartilage, is implicated by genetic and histologic analysis. Poland syndrome is a unique unilateral chest/hand deficiency that may include rib defects, pectoral muscle deficit, and syndactyly. Cleft sternum is a rare congenital defect resulting from nonfusion of the sternal halves, which leaves the heart unprotected and requires early surgical intervention.