A peculiar type of interstitial infiltrates in cryoglobulinemia glomerulonephritis (CryoGN).
ASN 30th Annual Meeting, San Antonio
J Am Soc Nephrol (Sep) 8:534A 1997
Cryoglobulinemia refers to the presence of circulating proteins which form a gel or crystallize when the plasma is cooled. It is an idiopathic condition in 30-50% of the cases, but may also be associated with multiple myeloma, Waldenstrom's macroglobulinemia, other B-cell neoplasms, autoimmune disorders, and systemic infections. Precipitation of cryoglobulins in the kidney is associated with proliferative glomerulonephritis.
Ferrario et al reviewed 36 renal biopsies obtained from patients with essential (idiopathic) cryoglobulinemia. On light microscopy, 17 biopsies (47.2%) showed diffuse or focal mononuclear infiltrates that appeared monomorphic. By immunohistochemical analysis, the interstitial infiltrate contained "great numbers" of CD19 +ve B-cells. Bone marrow biopsies showed "lymphatic activation" in 41% of biopsies. This constellation of findings is claimed to be unique to cryoglobulinemic glomerulonephritis, and is suggested to be of potential diagnostic importance. No correlations were found between biopsy findings and the clinical parameters of these patients.
Comment: This abstract is worded ambiguously, and insufficient information is contained to objectively evaluate its contents. Thus, the infiltrate is described as monomorphic, but the actual morphology is not described in standard hematopathologic terminology. One cannot ascertain whether the authors are infact dealing with lymphomatous infiltration, which is a well known cause of cryoglobulinemia. Clonal analysis of the infiltrate was apparently not perfomed. Likewise, increased number of B-cells is mentioned , but no range or standard deviation of the numeric counts is provided, and glomerulonephritides associated with diseases other than cryoglobulinemia were not studied as a control. The criteria used to determine that bone marrow biopsies showed "lymphatic activation" are also not explicitly stated.
This reviewer finds it hard to accept that increased number of B-cells in the interstitium is unique to cryoglobulinemic glomerulonephritis. The same finding would be expected in low grade B-cell neoplasms infiltrating the kidney, and in plasma cell rich infiltrates that are sometimes seen in interstitial nephritis associated with autoimmune diseases. Acute allograft rejection and lupus nephritis can also result in intense lymphoid hyperplasia with the formation of florid germinal centers. Ultimately, the diagnosis of cryoglobulinemic glomerulonephritis at biopsy can only be based on the actual demonstration of cryoglobulin deposits, and not on the morphologic or phenotypic characteristics of the associated inflammatory infiltrate. (Parmjeet Randhawa, M.D., Presbyterian-University Hospital, Pittsburgh, PA)
References:
D'Amico G, Colasanti G, Ferrario F, Sinico RA. Renal involvement in essential mixed cryglobulinemia. Kidney Int 1989;35:1004-1014.
Ben-Bassat M, Boner G, Rosenfeld J, et al. The clinicopathologic features of cryoglobulinemic nephropathy. Am J Clin Pathol 1983;79:147-156.
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ASN 30th Annual Meeting, San Antonio
Proteinuria/Hematuria : Cryoglobulinemia not due to hepatitis