When Waldenström macroglobulinemia hits the kidney: Description of a case series and management of a "rare in rare" scenario

Abstract

Background: Renal injury related to Waldenström macroglobulinemia (WM) occurs in approximately 3% of patients. Kidney biopsy is crucial to discriminate between distinct histopathological entities such as glomerular (amyloidotic and non-amyloidotic), tubulo-interstitial and non-paraprotein mediated renal damage. In this context, disease characterization, management, relationship between renal, and hematological response have been poorly explored. We collected clinical, genetic and laboratory data of seven cases of biopsy-proven renal involvement by WM managed at our academic center and focused on three cases we judged paradigmatic discussing their histopathological patterns, clinical features, and therapeutic options.

Case: In this illustrative case series, we confirm that serum creatinine levels and 24 h proteinuria are parameters that when altered should prompt the clinical suspicion of WM-related renal involvement, even if at present there are not precise cut-off levels recommending the execution of a renal biopsy. In our series AL Amyloidosis (n = 3/7) and tubulo-interstitial infiltration by lymphoma cells (n = 3/7) were the two more represented entities. BTKi did not seem to improve renal function (Case 1), while bortezomib-based regimens demonstrated a beneficial activity on the hematological and organ response, even when used as second-line therapy after chemoimmunotherapy (Case 3) and also with coexistence of anti-MAG neuropathy (Case 2). In case of poor response to bortezomib, standard chemoimmunotherapy (CIT), such as rituximab-bendamustine, represents an effective option (Case 1, 6, and 7). In our series, CIT generates durable responses more frequently in cases with amyloidogenic renal damage (Case 1, 5, and 7).

Conclusion: In this illustrative case series, we confirm that serum creatinine levels and 24 h proteinuria are parameters that when altered should prompt the clinical suspicion of WM-related renal involvement, even if at present there are not precise cut-off levels recommending the execution of a renal biopsy. Studies with higher numerosity are needed to better clarify the pathological and clinical features of renal involvement during WM and to determine the potential benefit of different therapeutic regimens according to the histopathological subtypes.

Keywords: Waldenström macroglobulinemia; amyloidosis; kidney disease; lymphoma; lymphoproliferative disorders.

FIGURE 1

Histological, immunofluorescence, ultrastructural patterns in kidney biopsy of three WM patients with renal involvement. (A) Amyloidosis AL (Case 1): (A1) enlargement of the mesangium and thickening of the glomerular basal membranes due to amorphous deposits, hematoxylin‐eosin staining, scale bar 200 μm, original magnification 200×, (A2) thioflavin at fluorescence showing positivity for amyloid deposits original, original magnification 200×, (A3) immunofluorescence against IgM with granular positivity at glomerular basal membrane, original magnification 200×, and (A4) electron micrograph with immunoreactivity for one light chain of amyloid fibrilles as demonstrated by a post‐embedding immunogold method in keeping with light chain lambda amyloidosis (original magnification 10 000×, in the box a close up at 20 000×). (B) Membranoproliferative glomerulonephritis and light chain deposition disease (Case 2): (B1) diffuse homogeneous thickening of the glomerular basal membrane, hematoxylin‐eosin staining, scale bar 200 μm, original magnification 200×, (B2) immunofluorescence against IgG with granular positivity at glomerular basal membrane, original magnification 200×, (B3,4) electron micropgraphs with subendothelial deposits at the glomerular basal membrane (black arrow) and light chain deposits (white arrow) in the tubular basal membrane [original magnification (B3) 2500× and (B4) 5000×]. (C) Direct kidney lymphoplasmacytic infiltration (Case 3): (C1,2) dense subcapsular and tubulointerstitial infiltrates by neoplastic lymphocytes, hematoxylin‐eosin staining, scale bar 200 μm, original magnification 200×, (C3,4) immunochemistry for B cells (CD20 staining), original magnification 200×.