[Primary renal triple expressor DLBCL treated with chemotherapy under continuous hemodialysis and filtration support]

A 69-year-old woman was previously treated with antibiotics for suspected pyelonephritis due to fever but showed limited improvement. Contrast-enhanced CT revealed heterogeneous areas of decreased contrast enhancement in both kidneys, along with an elevated soluble level of the IL-2 receptor (5,090 U/ml), and thus the patient was referred to our department for further evaluation. A percutaneous renal biopsy performed due to suspected malignant lymphoma confirmed lymphoma cell infiltration into the renal interstitium. Immunohistochemical staining was positive for MYC/BCL2/BCL6, leading to the diagnosis of stage IVB primary renal triple expressor diffuse large B cell lymphoma (DLBCL). Due to acute kidney injury, continuous hemodiafiltration (CHDF) was initiated, followed by rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemotherapy. The patient's renal function improved rapidly, and complete response was achieved after six cycles of R-CHOP. Although DLBCL is a common lymphoma, the primary renal subtype is extremely rare and poses both diagnostic and therapeutic challenges. This case highlights the potential clinical implications of combining CHDF with chemotherapy to achieve complete response despite an initial poor prognosis based on the patient's overall clinical condition and pathology.