Membranoproliferative glomerulonephritis complicating Waldenström's macroglobulinemia

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.

Type I Cryoglobulinemic Nephritis in a Patient of Monoclonal Gammopathy of Renal Significance

Monoclonal gammopathy of renal significance is a recently described entity in which a small B-cell clone not meeting the criteria for the diagnosis of multiple myeloma produces renal disease usually through deposition of a secreted monoclonal immunoglobulin. Here, we describe a case of Type I cryoglobulinemic glomerulonephritis diagnosed on a kidney biopsy and caused by a monoclonal IgM produced by a small bone marrow clone. The patient made a complete renal recovery after chemotherapy to suppress the clone.

A case of acute renal failure of multiple myeloma due to monoclonal type I cryoglobulinemia with thrombotic microangiopathy

The term cryoglobulinemia (CG) is used to refer to vasculitis due to so-called mixed cryoglobulins containing immune complexes. Although most cases of monoclonal CG, called type I CG, are asymptomatic, purpura, skin ulcers, and renal failure develop in some cases. Hematological disorders are the underlying diseases in most cases, on which the therapeutic strategies available and the prognosis of patients depends. We here report a case of a 47-year-old man who had pain in both his ankles, with palpable purpura and epistaxis, and presented with acute renal failure. Monoclonal immunoglobulin (Ig) G-κ protein was detected and cryoglobulin was also positive. Renal biopsy revealed emboli with a fibrillar structure in the glomeruli and renal tubule lumina. The complication of thrombotic microangiopathy (TMA) occurred during the course. Therefore, plasma exchange and hemodialysis were added to methylprednisolone pulse therapy. The treatment was successful, dissipating the purpura. However, the purpura relapsed and renal dysfunction progressed when the administration of oral steroids was tapered. Bone marrow biopsy was performed again, which indicated an increase in abnormal plasma cells. The patient was finally diagnosed as multiple myeloma. Then, bortezomib-dexamethasone therapy was initiated. This is the first case of type I CG with monoclonal IgG complicated by TMA during the course; it provides insight into the pathogenesis of renal dysfunction associated with type I CG.