Peripheral right upper lobe collapse in the newborn

Three forms of peripheral right upper lobe collapse are described. One form has a straight or slightly concave medial border that mimicks pleural fluid. A second variety protrudes from the inferior lateral aspects of the atelectatic right upper lobe producing a triangular opacity that tapers inferiorly toward the chest wall. A third variety produces a convex medial interface with the lung that simulates an extrapleural mass or loculated fluid. (orig.)