Undiagnosed Pulmonary Sequestration in a Young Adult Presenting As Necrotizing Pneumonia and Sepsis

Pulmonary sequestration is a rare congenital lung abnormality in which a portion of nonfunctioning lung tissue does not communicate with the tracheobronchial tree. Additionally, it receives its blood supply from systemic circulation rather than the pulmonary arteries. Although it is often diagnosed in childhood, some patients remain asymptomatic for years and are not identified until later in adolescence or adulthood. In this case, a 21-year-old male patient with no prior medical history presented with sepsis due to necrotizing pneumonia. His symptoms developed over several weeks and included recurrent respiratory complaints, weight loss, and acute chest and abdominal pain. CT angiography demonstrated an 8 × 9 cm microcystic lesion in the left lower lobe. The lesion was supplied by the descending thoracic aorta and drained into the pulmonary artery, findings consistent with intralobar pulmonary sequestration. Surrounding cavitary and ground-glass changes suggested a superimposed necrotizing infection. He was treated with broad-spectrum antibiotics along with supportive care and nutritional supplementation for associated protein-calorie malnutrition. Because of ongoing inflammation and concern for operative risk, thoracic surgery recommended delaying resection, with a plan for an interval left lower lobectomy once the infection had resolved. This case reflects a less typical presentation of pulmonary sequestration complicated by severe infection. It also serves as a reminder to consider congenital lung anomalies in young adults with recurrent or unexplained pulmonary infections, and highlights the importance of appropriate imaging and multidisciplinary coordination when determining management.