Although pulmonary tumor embolism (PTE) is a well-recognized end-stage form of pulmonary metastases at postmortem examination, the entity is rarely the first clinical sign of prostate cancer. Diagnosis of this condition in patients who have no previous history of malignancy is a challenge. Herein, we reported a 79-year-old man presented with progressive, unexplained dyspnea on exertion. Microscopic PTE coinciding with pulmonary lymphangitic carcinomatosis were readily recognized based on the presence of multifocal dilatation and beading of the peripheral pulmonary arteries with thickening of the bronchial walls and interlobular septa on the initial thin-section chest CT images. Pathologic examination of the transbronchial lung biopsy specimen revealed tumor emboli occluding both the small muscular pulmonary arteries and lymphatic vessels. These tumor cells were positive for prostatic specific antigen on immunohistochemical staining. The final diagnosis of prostatic adenocarcinoma was confirmed. Remarkable clinical and radiographic improvement was achieved following bilateral orchiectomies and anti-androgen treatment.