Unilateral primary lung hypoplasia diagnosed in adulthood

Unilateral primary pulmonary hypoplasia is rare in adulthood. It is usually present in the neonatal period or in early childhood, and is characterized by a decreased number of bronchial segments and decreased/absent alveolar air space. Most patients have recurrent episodes of wheezing or pneumonia and severe respiratory distress leading to chronic respiratory failure, whereas some patients may occasionally be asymptomatic. Herein, we present a case of left lung hypoplasia in an asymptomatic 28-year-old male, who was admitted to the hospital for further investigation of an abnormal result on a chest radiograph that was obtained as part of a health evaluation for military service. A thorough workup, including imaging modalities and bronchoscopy, disclosed a hypoplastic left lung, which had gone undiagnosed for 25 years. Embryological, clinical, and diagnostic aspects are briefly discussed.