Swyer-James (Macleod's) syndrome. Variations in pulmonary-bronchial arterial blood flow.

The Swyer-James (Macleod's) syndrome (or unilateral hyperlucency of the lung) frequently presents a diagnostic problem. Two cases of this entity are reported that demonstrate its similarity to and differentiation from pulmonary embolism and other intrapulmonic disorders. Detailed roentgenologic and physiologic studies were performed to define the diagnostic criteria of this syndrome. The reciprocal relationship of the bronchial arterial circulation in the hyperlucent lung was described.