Intralobar pulmonary sequestration masquerading as a giant lung abscess in a 16-year-old male: a case report and literature review.

BACKGROUND: Pulmonary sequestration (PS) is a rare congenital pulmonary dysplasia. Due to atypical clinical symptoms, PS is frequently challenging to differentiate from other common respiratory diseases. CASE PRESENTATION: A 16-year-old male presented with acute fever and expectoration as chief complaints. The patient had undergone tooth extraction more than one month prior. A chest computed tomography (CT) scan revealed a large cavity lesion with an air-fluid level in the left lower lobe, leading to an initial diagnosis of a lung abscess potentially caused by odontogenic flora. Elevated levels of carbohydrate antigen 19 - 9 (CA19-9) were detected in both serum and abscess drainage fluid. Due to an inadequate response to broad-spectrum antimicrobial therapy and percutaneous drainage of the lung abscess, the patient was referred for surgical intervention. Intraoperative findings revealed an anomalous arterial supply to the left lower lobe, confirming the diagnosis of intralobar pulmonary sequestration. Left lower lobectomy was successfully performed. CONCLUSION: Lung abscess may not represent a straightforward diagnosis. This case report highlights the necessity of including pulmonary sequestration in the differential diagnosis of lung abscess, particularly when clinicians encounter adolescent patients with significantly elevated CA19-9 levels. Chest computed tomography angiography is recommended as a diagnostic tool to reduce the risk of misdiagnosis and potentially life-threatening intraoperative hemorrhage.