Basilar hyperlucency in a patient with emphysema due to hypocomplementemic urticarial vasculitis syndrome.

Disproportionate emphysematous involvement of the lung bases, compared with the apices, sometimes called basilar hyperlucency, is an unusual radiographic pattern that has been reported primarily in patients with alpha-1 antitrypsin deficiency, but also in individuals with emphysema caused by intravenous injection of methylphenidate. We present a patient with emphysema associated with hypocomplementemic urticarial vasculitis syndrome and whose chest radiograph demonstrated basilar hyperlucency. To the extent that basilar hyperlucency has not been well recognized as a feature of hypocomplementemic urticarial vasculitis syndrome, this report extends the spectrum of causes of this unusual radiographic pattern of emphysema.