We herein report an 80-year-old man with prostatic carcinoma who developed eosinophilic pneumonia and intrathoracic metastases. He presented with shortness of breath, cough, and fever as a chief complaint. Chest X-ray and computed tomography showed bilateral pulmonary nodules, intrathoracic lymphadenopathy, and right-sided consolidation. Positron emission tomography (PET) using ¹⁸F-fluorodeoxyglucose (FDG) showed poor uptake in these nodules and lymph nodes. The patient subsequently received a pelvic computed tomography scan, which revealed a massively enlarged prostate. The serum prostate specific antigen level was elevated to 4,181.2 ng/mL, and a transrectal biopsy revealed prostatic adenocarcinoma. Based on the morphological and immunohistochemical findings, the nodules in the lung and the lymph nodes were diagnosed as secondary neoplasm from the prostate. As for right-sided consolidation, remarkable bronchoalvelar lavage fluid eosinophilia was detected, that was compatible with eosinophilic pneumonia. Eosinophilic pneumonia in this case disappeared and has not recurred by treatment of prostatic carcinoma and steroid therapy for a week, and was regarded to be tumor-associated. Although prostatic carcinoma with an initial manifestation of intrathoracic metastases and eosinophilic pneumonia is uncommon, physicians should suspect the condition. In addition, we should also keep in mind that prostatic carcinoma sometimes shows poor uptake in FDG-PET.
PET: Positron emission tomography, FDG: ¹⁸F-flouorodeoxyglucose