BK and JC polyomavirus co-infection resulting in polyomavirus nephropathy and progressive multifocal leukoencephalopathy at the same time, a case report

• First Reported Case: Simultaneous PML (JCV) and PVN (BKV) in a non-transplanted patient. • Beyond Transplant Patients: Highlights the need to consider polyomavirus nephropathy in hematologic malignancies. • High Viral Loads & Cross-Organ Impact: Suggests JCV may contribute to kidney injury and BKV may play a role in PML. • Clinical Implications: Supports systematic testing for both JCV and BKV in atypical PML or PVN cases. John Cunningham Virus (JCV) and BK Virus (BKV) are the most extensively studied Human Polyomaviruses (HPyVs), primarily associated with Progressive Multifocal Leukoencephalopathy (PML) and BKV Nephropathy (BKVN), respectively. While co-infection with these viruses has been documented in the same disease, simultaneous manifestation in distinct pathologies has not been previously reported. We present the first documented case of concurrent PML and Polyomavirus Nephropathy (PVN) due to reactivation of two different HPyVs, offering new insights into the clinical spectrum of HPyV-related diseases.