C63-49 Adult-onset Intralobar Pulmonary Sequestration Mimicking Chronic Infection and Malignancy

Abstract Introduction Pulmonary sequestration is a rare congenital lung malformation that is described by nonfunctional lung tissue that lacks a regular bronchial connection and receives a systemic arterial blood supply. Although typically diagnosed in childhood, intralobar sequestration (ILS) can occasionally present in adults, often mimicking infectious or malignant pulmonary processes. This case highlights an unusual adult presentation of ILS with chronic inflammatory and necrotic features. Case Presentation A 37-year-old man with a history of pneumonia and occupational exposures (refrigeration, construction) presented with progressive dyspnea and pleuritic chest pain over three months. He had experienced unintentional weight loss (20 lb), intermittent arthralgias, night sweats, and low-grade fevers. Denied a history of hemoptysis, TB exposure, or recent travel. Physical examination revealed cachexia, digital clubbing, and left basilar rhonchi. Laboratory tests were unremarkable. Chest CT scan revealed a stable, well-circumscribed left lower lobe mass with characteristics of an intralobar pulmonary sequestration (Figure 1). However, no definitive arterial supply was identified, confirming no major communication with the aorta. Nevertheless, there is concern that the arterial supply may arise from the intercostal, splenic, superior gastric, or a combination of them. Initial management included empiric piperacillin-tazobactam, and the infectious workup (including PPD) was negative. Given persistent concern for malignancy, the patient underwent a left lower lobectomy. Gross pathology revealed a 12.3 cm irregular cystic mass (335 g) with friable yellow-tan material and purulent contents. Histologic examination confirmed intralobar pulmonary sequestration with cystic changes and abscess formation. The regional lymph node was unremarkable. Postoperatively, the patient recovered uneventfully and had complete resolution of symptoms. Discussion Adult-onset ILS is uncommon and may closely resemble chronic infection or neoplasm. No evidence was found to demonstrate aortic feeding vessels, however this does not exclude the diagnosis, as variant systemic supplies can arise from smaller arteries. The definitive diagnosis is established by histopathologic confirmation and surgical resection. Early recognition is important to prevent further complications, such as abscesses, recurrent infections, or massive hemoptysis. Conclusion This case in particular emphasizes the importance of thinking of intralobular pulmonary sequestration in our differential diagnosis when evaluating chronic necrotic lung masses in adults. Even in the lack of a clearly visualized systemic arterial supply, radiologic suspicion combined with surgical pathology remains essential for accurate diagnosis and curative management. Figure 1: Chest CT scan showing a stable, well-circumscribed left lower lobe mass (A). Intralobar lung sequestration removed (B). This abstract is funded by: none