Reversible podocytopathy in a patient with blastoid-variant mantle cell lymphoma: A case of paraneoplastic FSGS and a literature review.

Mantle cell lymphoma (MCL) rarely causes glomerular disease. While immune complex-mediated and infiltrative lesions predominate, podocytopathies are exceptionally rare. We report a case of reversible focal segmental glomerulosclerosis (FSGS) occurring in the setting of blastoid-variant MCL, highlighting the paraneoplastic nature of the podocyte injury. A 69-year-old man presented with nephrotic syndrome and dialysis-dependent acute kidney injury (AKI). Kidney biopsy revealed FSGS. Subsequent diagnostic evaluation uncovered blastoid-variant MCL. Following lymphoma-directed chemotherapy, nephrotic syndrome resolved and renal function recovered, supporting a paraneoplastic mechanism of podocyte injury. This case underscores that MCL can induce a reversible paraneoplastic podocytopathy mimicking primary FSGS. Recognition of this entity is crucial to avoid unnecessary immunosuppression and to prompt early evaluation for underlying malignancy. Treating the neoplasm can result in renal recovery, emphasizing the functional connection between tumor activity and podocyte injury.