Case reports of immune-related cystitis and the antibody combination hypothesis.

Immune-related cystitis is a rare condition, and its diagnostic criteria and pathogenesis are not yet fully understood. Here, we report two cases of immune-related cystitis. Both patients were previously diagnosed with lung squamous cell carcinoma and received combined treatment with immune checkpoint inhibitors and chemotherapy, leading to hemorrhagic cystitis. We reviewed the cystoscopic images and pathological features of previous cases and found that autoantibodies against hemidesmosomes may be the cause of immune-related cystitis, proposing the "antibody combination" hypothesis to explain the tissue specificity of the condition.