What happened, in summary

A 63-year-old man with hypertension, type 2 diabetes, and a 40 pack-year smoking history was evaluated in April 2023 for weight-loss-type constitutional symptoms and diarrhea with blood. CT found a solitary 7 mm nodule in the right upper lung lobe, while colonoscopy suggested possible inflammatory bowel disease. In May 2024, he underwent right upper lobectomy with mediastinal lymph-node sampling by video-assisted thoracoscopic surgery. Final pathology showed lung adenocarcinoma, pT1bN2M0, consistent with Stage IIIA disease. PD-L1 expression was 49%. The pathology also documented triple-negative status, without expanding the specific markers. He began adjuvant cisplatin plus pemetrexed every 3 weeks for 4 cycles in July 2024. His diarrhea stopped during chemotherapy and shifted toward constipation. In October 2024, he started atezolizumab 1875 mg by subcutaneous injection every 3 weeks. After the third cycle, rectal bleeding returned and colonoscopy showed distal ulcerative colitis, leading to discontinuation of atezolizumab and treatment with oral and topical mesalazine. Symptoms worsened with fever, abdominal pain, frequent abnormal stools, and emergency visits. He was later admitted with markedly elevated liver transaminases, jaundice, choluria, acholia, cholestasis, and direct hyperbilirubinemia. Extensive autoimmune, viral, ultrasound, MRI, and endoscopic evaluation did not show another cause. Liver biopsy confirmed atezolizumab-induced vanishing bile duct syndrome. He received high-dose methylprednisolone pulses, prednisone, mycophenolate mofetil, ursodeoxycholic acid, vitamin K, and supportive prophylaxis. Liver transplant was not offered because of recurrence risk and the required disease-free interval after lung cancer. He was discharged clinically stable but with guarded prognosis and close oncology and autoimmune follow-up, with outpatient monitoring planned.