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Abstract: PO1911

Lysozyme Nephropathy: A Rare Yet Treatable Cause of AKI in Chronic Myelomonocytic Leukemia

Session Information

Category: Onco-Nephrology

  • 1500 Onco-Nephrology

Authors

  • Donati, Andrew, Yale University School of Medicine, New Haven, Connecticut, United States
  • Shirali, Anushree C., Yale University School of Medicine, New Haven, Connecticut, United States
Introduction

Lysozyme is a small lytic enzyme with bactericidal properties synthesized by monocytes that is freely filtered by the glomerulus. It can be produced in large quantities by neoplastic cells of monocytic lineage resulting in nephrotic range proteinuria (lysozymuria). Lysozyme can accumulate in proximal tubular cells thereby causing toxic injury resulting in tubular cell injury.

Case Description

A 69 year old woman was referred to nephrology clinic for evaluation of elevated serum Cr. Her past medical history included Type-2 Diabetes Mellitus, Hypertension, Hyperlipidemia, JAK2/V617F-positive Polycythemia Vera, Chronic Myelomonocytic Leukemia, bilateral renal angiomyolipomas and gout. Physical exam was unremarkable. Lab data were notable for creatinine (Cr) 1.7 mg/dL (baseline 1.2), Calcium 11.1 mg/dL, Uric acid 7.7 mg/dL, WBC 65.1 x 1000/uL (ANC 40.4; Monocytes 14.3), Hemoglobin 11.6 g/dL and Platelets 141 x 1000/uL. Electrolytes, liver function tests, and viral hepatitis serologies were within normal limits. Urinalysis was unremarkable. Urine albumin/Cr ratio was 79.4 mg/g of creatinine. A kidney biopsy was performed. Light microscopy revealed focal acute tubular injury and PAS-positive cytoplasmic granules. Electron microscopy revealed electron dense aggregates in the cytoplasm of the proximal tubular cells. Serum lysozyme was > 60 mcg/mL (reference range 5-11 mcg/mL). A diagnosis of lysozyme-induced nephropathy (LyN) was made. Repeat bone marrow biopsy revealed myeloid neoplasm with 13% blasts. She started treatment with Decitabine/Cedazuridine and her WBC improved to < 10 1 x 1000/uL and her Cr improved to 1.2 mg/dL.

Discussion

This case demonstrates an uncommon and often under-recognized cause of acute tubular injury in patients with chronic myelomonocytic leukemia. Lysozyme-induced nephropathy can be reversed with targeted therapy.

Light microscopy revealed focal acute tubular injury and PAS-positive cytoplasmic granules (PAS stain).