Endolymphatic Sac Tumors Associated With von Hippel-Lindau: A Case Report Highlighting Opportunity for Novel Orphan Drug Therapy.

Objective: To discuss the potential benefit of belzutifan therapy in a patient with von Hippel-Lindau (VHL) disease-associated endolymphatic sac tumor (ELST).

Patients: Case report.

Interventions: Clinical details of a patient with residual ELST after hearing preservation surgery who initiated belzutifan therapy postoperatively for concurrent renal cell carcinoma, as well as literature review of belzutifan and ELST.

Main Outcome Measures: The patient remained without radiologic evidence of growth of her residual tumor at 17 months post-initiation of belzutifan. It is unknown whether this represents therapeutic drug effect, nonviability of residual tumor, or slow tumor growth not captured radiographically within the duration of follow-up.

Conclusions: Belzutifan could have direct therapeutic benefit in patients with VHL-associated ELST.