Pseudothrombus deposition accompanied with minimal change nephrotic syndrome and chronic kidney disease in a patient with Waldenström's macroglobulinemia: A case report

Abstract

Background: Waldenström's macroglobulinemia (WM) is a rare lymphoid neoplasia, which can have renal complications. These rarely occur, and most common renal manifestations are mild proteinuria and microscopic hematuria. Herein we describe a case of WM that presented with pseudothrombi depositing in capillaries associated with minimal change nephrotic syndrome and chronic kidney disease (CKD).

Case summary: A 52-year-old man presented with features suggesting nephrotic syndrome. Extensive workups were done, and there were elevated serum levels of interleukin-6 and vascular endothelial growth factor (VEGF), capillary pseudothrombus accumulation associated with minimal change nephrotic syndrome, CKD, and WM. Treatment was directed at the patient's WM with bortezomib, thalidomide, and dexamethasone whereby serum immunoglobulin M (IgM) decreased. The damage of IgM on the kidney was corrected; thus, the patient's proteinuria and serum creatinine had improved. The patient is still under clinical follow-up.

Conclusion: It is essential for clinicians to promptly pay more attention to patients presenting with features of nephrotic syndrome and do extensive workups to come up with a proper therapy strategy.

Keywords: Case report; Chronic kidney disease; Nephrotic syndrome; Pseudothrombi; Waldenström's macroglobulinemia.

Figure 1

Light microscopy. The volume of residual glomeruli increased, the number of cells was 80-120 per glomerulus, mesangial cells and mesangial matrix were slightly increased, capillary loops were open, and the number of infiltrating cells was < 3 per glomeruli, mainly mononuclear cells. Red blood cells and “pseudothrombi” could be seen in several capillaries. One capillary loop was embedded into the urinary pole (HE staining; magnification, ×600).

Figure 2

Light microscopy. Periodic Schiff-Methenamine (PASM) and Masson staining. Fuchsinophilic depositions were found in the basement membrane and under the endothelium. The tubulointerstitium exhibited moderate lesions, with acute lesions on chronic damage. There was diffuse turbidity and granular degeneration in the tubular epithelial cells. Partial tubular epithelial cells presented small and fine vacuolar degeneration, and the basement membrane of tubules became thicker. Brush border of the tubules was absent. Protein casts could be seen in some lumens. The renal interstitial region could be found to be focally enlarged, and fibrosis index was 1+. Individual arterioles presented segmental hyalinosis (PASM and Masson staining; magnification, ×400).

Figure 3

Electron microscopy. Extensive effacement of podocyte foot processes, slight hyperplasia of mesangial matrix, and small amounts of electron dense depositions were observed in the mesangial area. Interstitial fibrosis of the kidney was obvious, and inflammatory cell infiltration was seen.