Pulmonary pleomorphic carcinoma treated with PD-1 inhibitor: Two case reports.

Pulmonary polymorphic carcinoma (PPC) is a rare and poorly differentiated form of non-small cell lung cancer (NSCLC), accounting for just approximately 0.1% to 0.4% of all NSCLC cases. Historically, the conventional treatments for PPC have been linked to a grim prognosis. However, with the advent of immune checkpoint inhibitors (ICIs), including PD-1 inhibitors, for the management of NSCLC, our center has witnessed encouraging outcomes in two PPC patients who underwent PD-1 inhibitor therapy. The first patient was a 70-year-old male who initially came to our attention after the discovery of a lung mass during a routine physical examination. A lung biopsy confirmed the diagnosis of PPC, and further complications included brain metastasis. Surgical intervention was conducted for the brain metastases, while PD-1 inhibitor therapy was employed for the lung tumors. The second patient was a 60-year-old male who was admitted with a history of persistent coughing and hemoptysis, which led to the diagnosis of a left lung tumor. Subsequent postoperative pathology revealed pulmonary adenocarcinoma coexisting with PPC. However, 2 months later, distant metastases were detected during a follow-up examination. The patient encountered difficulty in tolerating the adverse effects of chemotherapy, prompting the initiation of PD-1 inhibitor treatment. Notably, both patients underwent one cycle of PD-1 inhibitor therapy without encountering significant adverse reactions, and their responses proved to be promising during re-examinations. These findings suggest that surgery combined with immunotherapy PD-1 inhibitor therapy may represent an effective approach for the treatment of PPC.