What happened, in summary

A 72-year-old man had fever and sputum production for 4 months, with worsening symptoms during the final month. CT showed a large mass in the right lung and a large pleural effusion. Drainage relieved pressure on the lung, and cancer cells in the fluid were identified as adenocarcinoma. Bronchoscopy did not obtain malignant tissue, and he declined a needle biopsy of the lung mass. Imaging, tumor markers, and malignant pleural-fluid cytology supported Stage IV lung adenocarcinoma, cT4N+M1.

He began palliative first-line treatment with tislelizumab, cisplatin, and nab-paclitaxel. On day 22 of the first cycle, he suddenly became severely short of breath. High-flow oxygen was not enough, and his oxygen level fell to 50-60% during transfer to intensive care. He required intubation and mechanical ventilation. Fever rose to 38.9°C, and interleukin-6 was markedly elevated.

Blood clots in the lungs and other immediate causes were considered, but the overall pattern supported severe cytokine release syndrome caused by immunotherapy. Methylprednisolone 500 mg daily led to rapid improvement in heart-injury markers and stabilized his condition. Symptoms returned when the steroid dose was lowered and improved again after the dose was increased.

During a later gradual taper, he developed severe pneumonia related to prolonged ventilation. Despite treatment, the infection progressed, and he died.

The initial immune reaction improved with high-dose steroids, but he remained critically ill and needed prolonged ventilation. The later pneumonia became the immediate life-threatening complication during recovery. His lung-cancer diagnosis relied on malignant pleural-fluid cytology because no tissue biopsy of the mass was available.