Extralobar pulmonary sequestration presenting as a mediastinal malignancy.

Pulmonary sequestration is an uncommon congenital anomaly usually diagnosed in childhood. It frequently presents as a lower lobe mass with symptoms from vascular shunting, anatomic impingements, or associated anatomic defects. This case report describes an adult with asymptomatic extralobar sequestration involving the mediastinum and left upper lobe. The unusual location and radiographic appearance, suggestive of malignancy, led to prompt surgical exploration. We review the literature on this topic, focusing on anatomic variability and difficulties with preoperative diagnosis.