ALTHOUGH anomalous pulmonary arteries have long been recognized,1 the first description of such a vessel associated with sequestration of the lung is credited to the unpublished thesis of Fischer, cited by Müller in 1927.2 In 1941 Haight3 made brief reference to two cases, and others4 have since described isolated instances of this anomaly. With an increasing number of thoracic operations, more material became available, and in 1946 Pryce5 reported eight cases and reviewed the literature in detail.
There are several theories as to the origin of the vessel and the sequestrated mass of lung. Pryce5a has written extensively on the subject, and here only a brief mention is necessary. Embryologically the pulmonary artery develops in a vascular plexus which has connections with both dorsal and ventral aortae (Fig. 1). Because of embryonic shifts the connections to the dorsal aorta are normally disrupted. If there