[Unilateral hyperlucent lung induced by a carcinoid tumor: comments on the differential diagnosis and mechanisms of hypoperfusion].

We report the case of a 35-year-old woman in whom a systematic thoracic x-ray led to the diagnosis of unilateral hyperlucent lung due to a carcinoid tumor obstructing the main left bronchus almost completely. Injected computed tomography permitted diagnosis of left lung hypoperfusion and visualization of the tumor. After enlarged inferior left lobar resection, normal perfusion was observed six months later on the isotopic lung perfusion scan. Other reported causes of unilateral hyperlucent lung are discussed as well as pathophysiological mechanisms of lung hypoperfusion and hypoxic vasoconstriction.