Figure 4.

a, b: Two days after hospitalization, chest radiography as well as CT showed pneumothorax. In addition, the infiltrative shadows that were observed from the S1+2 through S4 field appeared as massive bullae, around which dense infiltrative shadows that extended up to the pleura were observed. The rapid alteration in the left lung was presumably caused by rupture and bleeding that occurred from a part of the pulmonary metastatic lesions. Furthermore, the airspace expanded in the form of a check valve to generate the bullae, which infiltrated into the pleura and led to the formation of the pneumothorax.