Hypogenetic right lung with partial anomalous pulmonary venous return and accessory diaphragm: a case of "scimitar lung"

Partial anomalous pulmonary venous return (PAPVR) is a rare congenital cardiovascular condition in which some of the pulmonary veins drain into the systemic circulation. We report on the cadaveric dissection of a 71-year-old Caucasian male donor who died of chronic obstructive pulmonary disease with hypertension. We noted a faint incisional scar on the thorax extending from the parasternal region at the 4th intercostal level to the midaxillary line. Since the straight-line incision followed the ribs and the scar was quite faint, surgery probably occurred when the donor was young. We also observed numerous surgical interventions of the heart, lungs, and vasculature to correct various defects. The morphology of the heart was normal, but was shifted more to the right side. An atrial septal defect (ASD) was closed with sutures. The right superior pulmonary vein that drained into the superior vena cava (SVC) was ligated close to the SVC and the right inferior, left superior, and inferior pulmonary veins all drained directly into the left atrium. We noticed a dilated coronary sinus entering the right atrium adjacent to the ASD; the ostium of the coronary sinus noticeably lacked the normal valve-like structure. We initially thought the right lung was a "horseshoe" lung, but realised that it was a "hypogenetic" lung with PAPVR and an accessory diaphragm. Compared to the left, the right secondary bronchi were much narrower and branched uncharacteristically, as seen in hypogenetic lung syndrome. The inferior lobe was highly disorganised, severely hypoplastic, and exhibited uncharacteristic morphology. The superior bronchopulmonary segment was markedly hypoplastic. The posterior and medial basal segments were not only hypoplastic and slender, but also extended like a tail to the left pulmonary cavity behind the heart/pericardium and in front of the oesophagus and aorta. The right lung, though hypoplastic, demonstrated patent bronchi and the lobes were inflatable. Based on the hypogenetic lung and PAPVR, we conclude that the donor exhibited 'scimitar' lung.