This case involvd a male aged 69. He was referred to our department due to the determination of lymphadenopathy at the pulmonary hilum/mediastinal portion and supraclavicular fossa during an examination of RS3PE syndrome. A biopsy was conducted from the supraclavicular lymph node, but it was diagnosed as metastasis of a poorly differentiated epithelial tumor. The patient had respiratory discomfort, and Pneumocystis jirovecii pneumonia was found during the examination. He had a remission of the symptoms with a two-week treatment, but multiple brain metastases appeared that had not been recognized at the beginning. He passed away approximately 3 months after the initial visit, and the cause was diagnosed as pulmonary pleomorphic carcinoma in a pathological autopsy. This was a rare case because there have been no previous reports of pulmonary pleomorphic carcinoma with RS3PE syndrome.