Duodenal Metastasis of Pulmonary Pleomorphic Carcinoma: A Case Report

Pulmonary pleomorphic carcinoma (PPC) is a rare subtype of lung sarcomatoid carcinoma that has a poor prognosis, and no standard therapy has been established. Here, we report the case of a 74-year-old man with PCC who showed rare duodenal metastasis. He was referred to our hospital with a mass shadow in the right lung. The patient was diagnosed with PPC clinical stage II B on the basis of immunohistochemical staining from bronchoscopy, and the tumor proportion score of programmed death-ligand 1 was 80%. He did not want any treatment. A year and a half later, progressive anemia was detected. The primary tumor was stable; however, abdominal computed tomography and esophagogastroduodenoscopy revealed a duodenal tumor with stenosis. He was diagnosed with duodenal metastasis from PPC, and he underwent gastrojejunal bypass surgery to prevent bowel obstruction. After surgery, he received pembrolizumab for chemotherapy. However, owing to the progression of peritoneum dissemination, he died 2 months later due to the onset of melena.