Nivolumab-Associated Cardiac Manifestation of Cutaneous T-Cell Lymphoma in a Patient With Concurrent Renal Cell Carcinoma.

Cardiac involvement by cutaneous T-cell lymphoma is exceedingly rare and poses considerable diagnostic and therapeutic challenges. Immune checkpoint inhibitors targeting programmed cell death-1 have reported variable activity in T-cell lymphomas and have been associated with paradoxical progression in select cases. We report a 72-year-old man with longstanding indolent CD8-positive cutaneous T-cell lymphoma and metastatic renal cell carcinoma who developed myocardial infiltration by lymphoma after prolonged nivolumab therapy. Diagnosis was established by surgical cardiac biopsy reporting CD3-positive, CD8-positive, and CD30-negative T-cell lymphoma with clonal overlap with prior cutaneous disease. Given concern for paradoxical progression, therapy was transitioned to avelumab, an antiprogrammed death ligand-1 antibody. After nivolumab discontinuation and transition to avelumab, the patient experienced complete metabolic resolution of cardiac involvement, improvement in cardiac biomarkers, and durable control of cutaneous lymphoma over more than 3 years of follow-up. This case highlights a temporal association between programmed cell death-1 blockade and atypical dissemination of cutaneous T-cell lymphoma, supported by biologic plausibility, and underscores a potential therapeutic distinction between programmed cell death-1 and programmed death ligand-1 inhibition in malignant T-cell disorders.