Targeting mutant VHL-gene results in therapy response in metastatic clear cell carcinoma of rete testis.

Epididymal and rete testis tumors are exceedingly rare. We report a 69-year-old male who presented with progressive swelling of the right testis/epididymis; histopathology confirmed clear cell carcinoma of the rete testis. Staging with FDG-PET-CT revealed bilateral pulmonary metastases. Subsequent gene panel sequencing identified a pathogenic variant of VHL and a likely pathogenic variant of TP53. Off-label treatment with belzutifan was initiated. Regression of the pulmonary lesion with ongoing complete remission at 12 months of follow-up was observed. This case highlights the importance of molecular profiling for personalized therapy in rare tumor entities.