A case of lysozyme-induced nephropathy with improved renal function following treatment for chronic myelomonocytic leukemia.
Norihiro Nukui, Ei Kusahana, Kimihiro Matsumoto et al.
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Case in brief
A 75-year-old man with longstanding diabetes presented with weight loss and progressive anemia and was diagnosed with chronic myelomonocytic leukemia (CMML). His renal dysfunction was initially attributed to diabetic nephropathy, but it worsened and was accompanied by predominantly non-albumin proteinuria. Kidney biopsy showed lysozyme-induced nephropathy. CMML-directed treatment was started to preserve renal function; eGFR improved from 10.2 to 17.8 mL/min/1.73 m², and dialysis was avoided despite advanced kidney failure.
What made this case unusual
Renal injury from lysozyme-induced nephropathy was initially mistaken for diabetic nephropathy, and kidney involvement prompted CMML-directed treatment despite the patient not meeting conventional hematological treatment criteria.
Diagnostic / clinical pearl
In patients with myeloid neoplasms and monocytosis, worsening renal dysfunction with non-albumin-dominant proteinuria should prompt consideration of lysozyme-induced nephropathy and kidney biopsy.
Why it matters
This case illustrates that renal involvement in CMML may be a clinically significant organ manifestation, even when conventional hematological indications for treatment are absent.