Unusual cause of sudden-onset pleuritic chest pain: Torsion of extralobar pulmonary sequestration

Extralobar pulmonary sequestration (EPS) is often diagnosed in neonates due to accompanying congenital anomalies. However, even in adulthood, this condition can, in rare cases, be complicated with torsion and may present with pleuritic chest pain at an emergency department in an undiagnosed state. We describe a case with torsion of ELS in a healthy adult female. A 21-year-old woman presented with acute-onset back pain and pleuritic chest pain at our emergency department and was initially diagnosed with pleurisy based on normal results of investigations. However, she revisited our department due to flare-ups of pain, and a subsequent CT scan revealed an expanding homogeneous opacity in the left lower lobe of the lung. Magnetic resonance imaging (MRI) confirmed the presence of an encapsulated mass with a hypointense signal on T2-weighted imaging and a feeding artery from the aorta to the mass, leading to a preoperative diagnosis of EPS with hemorrhagic infarction. Video-assisted thoracoscopic surgery was performed, and the cause of hemorrhagic infarction was found to be a torsion. The diagnosis was confirmed histologically. This case highlights the importance of recognizing torsion of EPS as an unusual cause of pleuritic chest pain and emphasizes the need for early diagnosis in order to perform surgery as soon as possible. Changes in CT findings of torsion of EPS over time can help physicians understand this rare condition. MRI may also be useful for the perioperative diagnosis.