B60-24 Computed Tomography Angiography Solves the Mystery: Extra-Lobar Pulmonary Sequestration Mimicking Malignancy in an Adolescent

Introduction A pulmonary sequestration is nonfunctioning lung tissue that lacks normal tracheobronchial communication and receives its blood supply from a systemic artery. Extra-lobar sequestration (ELS) represents the less common subtype in which the blood drainage is also systemic, and is typically diagnosed incidentally or during infancy. Torsion of an ELS causing acute chest symptoms and pleural effusion is rare. We report a previously healthy adolescent presenting with dyspnea, pleuritic pain, and a pleural-based mass identified as an ELS with a feeding vessel from an accessory renal artery, in whom CT angiography (CTA) was able to provide a more definitive diagnosis than routine computed tomography (CT) with contrast. Description A 13-year-old male with a history of asthma presented with one week of sharp left-sided chest pain and dyspnea. Chest radiograph showed a small left pleural effusion with an infrahilar opacity. He was treated for presumed viral airway disease but re-presented with persistent pain. Contrast-enhanced chest CT revealed a 2.4 × 1.5 cm pleural-based mass with a small effusion (Figure 1A), raising concern for malignancy. Pleural fluid analysis suggested exudate, and CT-guided biopsy showed nonspecific necrotic and hemorrhagic fibrovascular tissue without infection or malignancy. A whole-body positron emission tomography-magnetic resonance imaging (PET-MRI) suggested an inflammatory or congenital process rather than malignancy. Chest CTA demonstrated the lesion was supplied by a systemic arterial branch arising from an accessory left renal artery (Figure 1B) confirming the diagnosis of an extra-lobar pulmonary sequestration. The patient’s symptoms resolved spontaneously, and surgical resection was deferred in favor of conservative observation. Discussion This case highlights several important points: 1) The definitive role of CTA compared with routine CT with contrast in diagnosing pulmonary sequestration, which can prevent unnecessary further invasive or high-cost investigations. The rapid, timed injection of contrast with CTA improves the resolution of the feeding artery, avoiding the need for further imaging and enabling prompt and accurate diagnosis. 2) Most pulmonary sequestrations arise from the thoracic or abdominal aorta; origin from an accessory renal artery is exceptionally uncommon. 3) While infection of a sequestration is more common than necrosis and pleural effusions, the latter suggest an ELS due to torsion of a feeding vessel stalk, even in the absence of visualization of a systemic draining vessel. Stable, asymptomatic, or mildly symptomatic ELS can be safely managed conservatively with close follow-up, reserving resection for recurrent or complicated cases. This abstract is funded by: Dr. Julian Allen is supported by grant funding from the Capek Foundation.