Case Report: Pembrolizumab-associated seronegative sicca syndrome during continued immunotherapy and after drug withdrawal in metastatic urothelial carcinoma

A case report describes a 78-year-old man with metastatic upper tract urothelial carcinoma who developed sudden and severe dry mouth and dry eyes 45 days after initiating pembrolizumab treatment, an immune checkpoint inhibitor. Tests confirmed reduced function of tear and salivary glands. Autoantibodies were absent and other causes of sicca were excluded, supporting a diagnosis of pembrolizumab-associated seronegative sicca syndrome. Symptoms were mild to moderate and manageable with artificial tears, saliva substitutes, and pilocarpine medication. Pembrolizumab was continued for 19 additional cycles with ongoing cancer control and symptoms did not worsen. After drug withdrawal, xerostomia improved substantially and the patient regained the ability to swallow dry foods without additional fluid. The case suggests that in carefully selected patients, mild sicca syndrome caused by immunotherapy may be managed symptomatically while continuing treatment.