Successful management of severe Pneumocystis jirovecii pneumonia with inhaled nitric oxide and individualized ventilatory strategies in an immunosuppressed patient: a case report.

BACKGROUND

Immune checkpoint inhibitors (ICIs) have improved survival in extensive-stage small-cell lung cancer (SCLC) but may cause checkpoint inhibitor pneumonitis (CIP). Management of CIP often requires prolonged high-dose corticosteroids, leading to profound immunosuppression and increased risk of opportunistic infections. Among these, Pneumocystis jirovecii pneumonia (PJP) is a life-threatening complication in non-HIV patients and carries higher mortality than HIV-associated PJP. Early etiological diagnosis is therefore essential. We report a case of severe PJP diagnosed by metagenomic next-generation sequencing (mNGS) and successfully managed with comprehensive respiratory support.

CASE PRESENTATION: A 69-year-old HIV-negative man with extensive-stage SCLC received four cycles of etoposide-platinum chemotherapy plus adebrelimab. Subsequently, CIP developed and required prolonged high-dose methylprednisolone therapy. He was transferred to our hospital for progressive dyspnea. Evaluation showed severe hypoxemia (PaO₂/FiO₂ 185 mmHg) and markedly elevated serum 1,3-β-D-glucan (3327.99 pg./mL). Bronchoalveolar lavage fluid mNGS identified P. jirovecii as the predominant pathogen, with Klebsiella pneumoniae, Pseudomonas aeruginosa, and Candida albicans indicating mixed pulmonary infection. The patient received trimethoprim-sulfamethoxazole, cefoperazone-sulbactam, and caspofungin. Worsening respiratory failure required endotracheal intubation and mechanical ventilation. Lung recruitment maneuvers, individualized positive end-expiratory pressure titration, and adjunctive inhaled nitric oxide progressively improved oxygenation, allowing successful extubation and eventual discharge.

CONCLUSION

Severe PJP should be considered in non-HIV patients receiving corticosteroids for CIP. mNGS enabled rapid pathogen identification and targeted therapy. Comprehensive respiratory support, including optimized mechanical ventilation and inhaled nitric oxide, may be valuable in managing life-threatening opportunistic infections in immunosuppressed patients.