Figure 13a. Bullous emphysema in a 27-year-old man with a long history of heavy marijuana use and only modest tobacco consumption. (a) Chest radiograph obtained at presentation shows a large left-sided pneumothorax. There are also bullae at the right apex. (b) High-resolution CT image (window level = –500 HU, window width = 1500 HU) obtained after reinflation of the left lung shows large bilateral apical bullae. The remainder of the lungs was normal. (c) Follow-up chest CT image obtained 4 years later after continued heavy marijuana use shows progression of the bullous lung disease.