Pneumocystis pneumonia in stage IIIA lung adenocarcinoma with immune-related acute kidney injury and thoracic radiotherapy: A case report

BACKGROUND Immune checkpoint inhibitors (ICIs) are therapeutic agents for advanced and metastatic non-small cell lung cancer (NSCLC) with high clinical antitumor efficacy. However, immune-related adverse events occur in 20% of these patients and often requiring treatment with immunosuppressive agents, such as corticosteroids. Consequently, this may increase the risk of patients to opportunistic infections. Pneumocystis jirovecii pneumonia (PJP), a rare but serious opportunistic infection typically observed in patients with human immunodeficiency virus, can also occur in cancer patients undergoing long-term glucocorticoid treatment. CASE SUMMARY We report a case of a 56-year-old male with squamous NSCLC treated with triplimab combined with paclitaxel, carboplatin, and radical thoracic radiation therapy. Following this regimen, he developed acute kidney injury (AKI) with elevated creatinine levels. After concurrent radical chemoradiotherapy ended, he developed a grade 3 immune-related AKI. High-dose corticosteroids were administered to treat AKI, and renal function gradually recovered. Corticosteroids were reduced to a dose of 10 mg prednisone equivalent daily eight weeks later; however, he developed severe pneumonia with spontaneous pneumothorax. Next-generation sequencing of the bronchoscopic lavage revealed PJP co-infection with herpes simplex virus 1 and cytomegalovirus. The inflammation was more severe in areas exposed to radiation. Piperacillin-tazobactam, acyclovir, sulfamethoxazole, and trimethoprim were used to control the infection. The patient recovered, and immunotherapy was terminated. CONCLUSION PJP is rare but can occur in patients with ICI adverse events and should be differentiated from tumor progression or immune-related adverse events. Thoracic radiation may increase risk, necessitating careful monitoring and prevention.