Transthoracic herniation of the fetal lung: bagpipe lung.

We describe a case of subtotal herniation of a lung through an intercostal space into an extrathoracic (axillary) position that occurred in a 16-week-old fetus. There was no malformation of the thoracic wall other than the hiatus at the site of herniation. The left and the right lungs were of similar size and weights and the lung/body weight ratio was normal. Histology revealed no difference between the normal and the abnormally positioned lung. We were unable to find a report of a similar case of the condition, which has implications for concepts of lung development.