[Two cases of prostate cancer found primarily from lung metastatic lesions]

We report two cases of prostate cancer found primarily from a metastatic lesion appearing in a chest radiograph. Patient 1 was admitted to our hospital because his chest radiograph and chest CT showed pleural effusion on the left. Thoracocentesis and pleural biopsy were unremarkable, so he was observed as both an outpatient and an inpatient. His general condition worsened, and after the third admission, he died. His autopsy revealed prostate cancer and positive immunohistochemical reactions for PSA and PSAP in both lungs, and prostate specimens demonstrated that prostate cancer had metastasized to the lung. Patient 2 was referred for evaluation of a bilateral multiple nodular shadow in a chest radiograph, and prostate cancer was discovered. Immunohistochemical reactions for PSA and PSAP were positive in both specimens of TBLB and prostate biopsy, confirming that the multiple lung tumors were metastases from prostate cancer.