What happened, in summary

A 66-year-old man was diagnosed with Stage II squamous cell lung cancer in 2022. He underwent removal of the right middle and lower lung lobes with lymph-node dissection, followed by four cycles of carboplatin, paclitaxel and the immunotherapy drug tislelizumab. He then received 13 additional cycles of maintenance tislelizumab. Months after treatment, he developed worsening fatigue, poor appetite, nausea, vomiting, low blood pressure and severe low sodium. Imaging and bronchoscopy showed no lung-cancer recurrence or metastasis. Hormone testing instead showed very low cortisol with an inappropriately low ACTH level, supporting secondary adrenal insufficiency associated with prior immunotherapy. He improved after intravenous hydrocortisone and was discharged on oral glucocorticoid replacement. Follow-up testing continued to show suppressed adrenal function, so replacement treatment was maintained. By telephone follow-up in June 2026, he had not experienced another adrenal crisis. His cancer remained without documented recurrence on the most recent oncologic evaluation, while the delayed endocrine complication required ongoing long-term management.