Subdiaphragmatic extralobar pulmonary sequestration.

A 21-day-old girl presented with a left subdiaphragmatic retroperitoneal mass discovered on maternal ultrasound at 23 weeks' gestation. The clinical impression was neuroblastoma, and preoperative workup showed no for metastatic disease. Histologically, the lesion proved to be an extralobar pulmonary sequestration. We present this case to remind pathologists of the occurrence of subdiaphragmatic pulmonary sequestration and its potential clinical confusion with other more familiar lesions that may occur in this location in a neonate.