Evans syndrome during pembrolizumab therapy for upper urinary tract cancer

INTRODUCTION: Immune checkpoint inhibitors are available for the treatment of advanced urothelial carcinoma; however, serious adverse events occasionally occur. Here, we report a rare case of Evans syndrome attributed to the use of an immune checkpoint inhibitor. CASE PRESENTATION: A 56‐year‐old man was diagnosed with left renal pelvic cancer and underwent left laparoscopic radical nephroureterectomy. Eight months postoperatively, computed tomography revealed para‐aortic lymph node metastasis. Despite receiving chemotherapy, the disease progressed, and pembrolizumab was initiated. After 26 months of pembrolizumab treatment, the patient developed fever and anemia. Hematologic examination confirmed the diagnosis of Evans syndrome. He was treated with blood transfusions and corticosteroids, and gradual symptom improvement was observed. CONCLUSION: This report highlights the potential risk of Evans syndrome associated with immune checkpoint inhibitor treatment. Clinicians should be aware of this possibility and consider early intervention with corticosteroids.