LAUSR

RATIONALE Left bronchial isomerism is generally associated with abnormal arrangement of the atrium and abdominal viscera; therefore, its diagnosis is confirmed in early childhood. PATIENT CONCERNS Here we report a rare case involving a 36-year-old man with isolated left bronchial isomerism that presented as an asymptomatic severe obstructive ventilatory disturbance during pulmonary function tests performed as part of routine assessments for an orbital wall fracture. The patient was a current smoker and did not show any respiratory symptoms. DIAGNOSIS Chest computed tomography revealed left bronchial isomerism, and further tests showed that there was no involvement of other organs. INTERVENTIONS We recommended smoking cessation and the long-term use of an inhaled long-acting bronchodilator. OUTCOMES The findings from this case highlight the causative role of left bronchial isomerism in asymptomatic adults with chronic obstructive pulmonary disease. LESSONS Physicians should consider this condition as a cause of obstructive ventilatory disturbances in asymptomatic adult patients.