[Lysozyme-induced nephropathy: A rare cause of renal failure in chronic myelomonocytic leukemia]

Kidney and Urinary Tract Involvement in Chronic Myelomonocytic Leukemia

Chronic myelomonocytic leukemia (CMML) is a hematologic malignancy affecting the bone marrow and resulting in peripheral blood monocytosis. Kidney and urinary tract involvement is common and can present dramatically with life-threatening consequences. Kidney involvement can be the result of direct or indirect mechanisms, including prerenal azotemia, glomerular disease, tubulointerstitial involvement, and renovascular disorders. Urinary tract involvement, electrolyte and acid-base disorders, as well as nephrotoxicity from treatment of the disorder can also occur. Given this multifactorial pathogenesis involving several mechanisms concomitantly, nephrologists must exercise heightened awareness and maintain a low threshold for kidney biopsy. There is a pressing need for future research endeavors to elucidate and target the manifestations of CMML that involve the kidneys with the ultimate goal of augmenting overall prognosis and therapeutic outcomes.

Lysozyme-induced nephropathy due to systemic granulomatous disease

Lysozyme-induced nephropathy is a rare form of acute tubular injury that has almost exclusively been reported in patients with monocytic malignancies. Typically, patients will present in acute renal failure A renal biopsy is necessary to confirm the diagnosis and will demonstrate proximal tubular cells with hypereosinophilic granules, which are periodic acid-Schiff and Jones methenamine silver-positive. Immunohistochemical staining for lysozyme will also be present. The following rare case will describe a case of lysozyme nephropathy in a patient without any underlying hematological malignancy, but instead with systemic granulomatous disease.

Lysozyme-Induced Nephropathy: A Diagnosis Not to Forget

Kidney injury in hematologic malignancies can manifest in many ways. We present a case report of a 44-year-old female with de novo acute myeloid leukemia (AML) and acute kidney injury. Following the etiological investigation, lysozyme-induced nephropathy was believed to be the most probable cause of renal injury. Intensive cytoreduction and chemotherapy were started and the patient's cytopenias and kidney injury have improved. This case highlights the importance of recognizing lysozyme-induced nephropathy as a form of kidney injury in AML. Despite being frequently underrecognized, a precocious diagnosis may impact the patient's prognosis.

Hematological Malignancies and the Kidney

The incidence of hematologic malignancies is on the rise worldwide. Kidney disease is ubiquitous in patients with hematologic malignancies, encompassing a wide spectrum of disorders involving each kidney compartment, including the vasculature, tubules, interstitium, and glomerulus, and there is significant overlap of kidney involvement with each hematologic malignancy. Vascular disorders include both microvascular and macrovascular damage, via thrombotic microangiopathy, hyperleukocytosis, hyperviscosity, and cryoglobulinemia. The tubulointerstitial compartment may be affected by prerenal azotemia and acute tubular injury, but malignant infiltration, tumor lysis syndrome, extramedullary hematopoiesis, cast nephropathy, granulomatous interstitial nephritis, and lysozymuria should be considered in certain populations. Obstructive uropathy may occur due to nephrolithiasis or retroperitoneal fibrosis. Glomerular disorders, including membranoproliferative, membranous, minimal change, and focal segmental glomerulosclerosis, can rarely occur. By understanding how each compartment may be affected, care can best be optimized for these patients. In this review, we summarize the widely varied etiologies of kidney diseases stratified by kidney compartment and hematologic malignancy, focusing on demographics, pathology, pathophysiology, mechanism, and outcomes. We conclude with common electrolyte abnormalities associated with hematologic malignancies.

A rare cause of acute kidney injury with chronic myelomonocytic leukemia

An 80-year-old man with myelodysplastic syndrome developed acute kidney injury (AKI) and peripheral blood monocyte-dominant leukocytosis. Glomerular disease was suspected from urinalysis, which showed proteinuria and microscopic hematuria with red cell casts. Eventually, he died of respiratory failure, after which a postmortem was performed. In the glomeruli, the extracapillary space was filled with numerous mononuclear cells and erythrocytes. At first interpretation, the glomerular findings appeared to represent cellular crescents. However, immunostaining revealed that the extracapillary mononuclear cells were in fact leukemic cells. Furthermore, tubular injury due to marked accumulation of lysozyme was also recognized together with infiltration of leukemic cells in the interstitium. The diagnosis of kidney infiltration by chronic myelomonocytic leukemia (CMML) and lysozyme-induced tubular injury was eventually made. Our case is the first report showing extracapillary infiltration of leukemic cells by immunostaining. In addition, lysozyme-induced tubular injury is a forgotten cause of kidney injury in patients with CMML. This case teaches us the rare and forgotten causes of AKI with CMML.