Unusual Cause of Left Chest Volume Loss

Abstract

Volume loss is commonly encountered at chest imaging and may result from a number of causes, including endobronchial obstruction from mucous impaction or centrally obstructing neoplasms, previous surgical resection, and visceral pleural restriction from prior pleural inflammation or intervention. Typically these conditions can be readily distinguished from one another through careful review of the chest radiographic appearance, comparison with prior radiographs, and correlation with appropriate clinical history; occasionally, thoracic computed tomography may be required to clarify chest radiographic findings. When the more common causes of unilateral thoracic volume loss have been excluded, rare causes of unilateral reduced lung volume, particularly congenital and developmental lesions should be considered. Pulmonary agenesis and aplasia may be discovered in childhood but may rarely escape detection into adulthood. These 2 conditions present with extensive unilateral volume loss and shift of the cardiomediastinal structures toward the affected side, with no visible lung tissue on the affected side. Pulmonary agenesis and hypoplasia essentially differ only in the presence of a blind-ending rudimentary bronchus in pulmonary aplasia; no bronchus is present in pulmonary agenesis. Pulmonary hypoplasia may occur in utero or develop as a result of childhood respiratory infections, and is characterized by reduced number and size of alveoli. On chest imaging, pulmonary hypoplasia presents as a unilateral volume loss associated with a small pulmonary artery on the affected side. Unlike pulmonary agenesis and aplasia, patients with pulmonary hypoplasia have at least some lung tissue present, and they may present with a unilateral hyperlucent lung, rather than complete hemithorax opacification, and thus may be distinguished from patients with pulmonary agenesis and aplasia.