The characteristics of seronegative and seropositive non-hepatitis-associated cryoglobulinemic glomerulonephritis

Clinicopathologic Characteristics of Crystalglobulin-Induced Nephropathy: A Case Series

RATIONALE & OBJECTIVE

Crystalglobulinemia is a rare syndrome characterized by intravascular crystallization of monoclonal immunoglobulins (MIgs). Data on kidney involvement are limited to case reports. This series characterizes the clinicopathologic spectrum of crystalglobulin-induced nephropathy (CIN).

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

Nineteen CIN cases were identified from the nephropathology archives of Mayo Clinic and Columbia University. CIN was defined by intravascular (extracellular) MIg crystals visible by light (LM) and electron microscopy (EM).

FINDINGS

Among the cases, 68% were male and 65% were Caucasian (median age 56 years). Most patients presented with severe AKI (median creatinine 3.5 mg/dL), hematuria, and mild proteinuria (median 1.1 g). Common extrarenal manifestations were constitutional (67%), cutaneous (56%), and rheumatologic (50%). Fifty percent of cases had hypocomplementemia. The hematologic disorders were monoclonal gammopathy of renal significance (MGRS) (72%), lymphoma (17%), or myeloma (11%), with 65% of these disorders discovered concomitantly with CIN. All patients had MIg identified on SPEP/SIF (IgGκ in 65%). The sFLC ratio was outside the renal range in 40%, and bone marrow biopsy detected the responsible clone in 67%. On LM, crystals involved glomeruli (100%) and vessels (47%), often with an inflammatory reaction (89%) and fibrin (58%). All cases exhibited crystal substructures (mostly paracrystalline) by EM. Immunofluorescence (IF) on paraffin embedded tissue was more sensitive than frozen tissue (92% versus 47%) for demonstrating the crystal composition (IgGκ in 63%). Follow up (median 20 months) was available in 16 patients. Eighty-one percent received steroids, 44% plasmapheresis, 38% hemodialysis, and 69% chemotherapy. Ninety-percent of patients who received clone-directed therapy achieved kidney recovery vs. 20% of those who did not (p=0.017).

LIMITATIONS

Retrospective design, small sample size.

CONCLUSIONS

CIN is a rare cause of nephropathy associated with lymphoplasmacytic disorders (mostly MGRS) and typically presents with severe AKI and extrarenal manifestations. Diagnosis often requires IF performed on paraffin embedded kidney tissue. Prompt initiation of clone-directed therapy, coupled with corticosteroids and plasmapheresis, may lead to recovery of kidney function.

Cryocrystalglobulinemia Leading to Multi-Organ Failure in Chronic Lymphocytic Leukemia Achieving Complete Renal Recovery

Cryocrystalglobulinemia (CCG) is a rare and fatal subset of type I cryoglobulinemia that is classically associated with an underlying monoclonal gammopathy. Cryocrystalglobulins are created when immunoglobulins self-assemble into extracellular crystal arrays, which often leads to severe systemic hypoperfusion and occlusive vasculopathy that culminates in multi-organ failure. Most commonly, the resultant ischemia manifests as cutaneous lesions and renal insufficiency, which can progress to fulminant kidney failure requiring renal replacement therapy. CCG is commonly associated with lymphoproliferative disorders and is most frequently reported in the literature in context of plasma cell dyscrasias with minimal cases describing CCG secondary to other types of lymphoid neoplasms, especially those that attain complete organ recovery. We report a unique case of a patient who presented with multi-organ failure, including cryoglobulinemic glomerulonephritis (CryoGN) consistent with monoclonal gammopathy of renal significance (MGRS), who was found to have type I IgG kappa CCG due to chronic lymphocytic leukemia (CLL). With the assistance of plasmapheresis, hemodialysis, and clone-directed therapy, the patient achieved complete renal recovery. We highlight this uncommon entity to emphasize the clinical importance of early diagnosis and timely treatment given CCG's significant morbidity and mortality.

Pathological characteristics of light chain crystalline podocytopathy

Monoclonal immunoglobulin light chain (LC) crystalline inclusions within podocytes are rare, poorly characterized entities. To provide more insight, we now present the first clinicopathologic series of LC crystalline podocytopathy (LCCP) encompassing 25 patients (68% male, median age 56 years). Most (80%) patients presented with proteinuria and chronic kidney disease, with nephrotic syndrome in 28%. Crystalline keratopathy and Fanconi syndrome were present in 22% and 10%, respectively. The hematologic condition was monoclonal gammopathy of renal significance (MGRS) in 55% and multiple myeloma in 45%. The serum monoclonal immunoglobulin was IgG κappa in 86%. Histologically, 60% exhibited focal segmental glomerulosclerosis (FSGS), often collapsing. Ultrastructurally, podocyte LC crystals were numerous with variable effacement of foot processes. Crystals were also present in proximal tubular cells as light chain proximal tubulopathy (LCPT) in 80% and in interstitial histiocytes in 36%. Significantly, frozen-section immunofluorescence failed to reveal the LC composition of crystals in 88%, requiring paraffin-immunofluorescence or immunohistochemistry, with identification of kappa LC in 87%. The LC variable region gene segment, determined by mass spectrometry of glomeruli or bone marrow plasma cell sequencing, was IGKV1-33 in four and IGKV3-20 in one. Among 21 patients who received anti-plasma cell-directed chemotherapy, 50% achieved a kidney response, which depended on a deep hematologic response. After a median follow-up of 36 months, 26% progressed to kidney failure and 17% died. The mean kidney failure-free survival was 57.6 months and was worse in those with FSGS. In sum, LCCP is rare, mostly associates with IgG κappa MGRS, and frequently has concurrent LCPT, although Fanconi syndrome is uncommon. Paraffin-immunofluorescence and electron microscopy are essential to prevent misdiagnosis as primary FSGS since kidney survival depends on early diagnosis and subsequent clone-directed therapy.

An Unusual Case of Seronegative Cryoglobulinemic Glomerulonephritis with Dominant Organized IgA Deposits Associated with Staphylococcal Infection: Casual or Causal Relationship?

Introduction

Cryoglobulinemia refers to the presence of cryoglobulins (CGs) in the serum, encompassing a group of diseases caused by the type of circulating GC. Cryoglobulinemic glomerulonephritis (CryoGN) is the principal manifestation of renal involvement. The diagnosis may be challenging because the hallmark of cryoglobulinemia is the detection of CG in the serum. However, cases of CryoGN without serological evidence of CGs are not uncommon in clinical practice, often diagnosed by anatomopathological findings in the renal biopsy.

Case Presentation

We report the case of an 86-year-old male who developed renal impairment, nephritic syndrome, and nephrotic-range proteinuria, without serological evidence of CGs, associated with staphylococcal bacteremia without apparent focus. Renal biopsy and pathological examination showed a membranoproliferative glomerulonephritis pattern with CD61-negative pseudothrombi. Immunofluorescence microscopy showed atypical IgA-dominant deposits. Electron microscopy revealed amorphous subendothelial and mesangial deposits and organized electrodense deposits within capillary loops (pseudothrombi) with microtubular substructure measuring 20-40 nm in thickness. These findings were consistent with seronegative CryoGN and microtubular organized atypical IgA-dominant deposits.

Discussion

In this report, we discuss the clinical, analytical, and histopathological findings of a rare case of CryoGN without serological evidence of CGs. Regarding the etiology that triggered the glomerular disease in our patient, we conducted an exhaustive study in order to determine the underlying cause of CryoGN. At the time of biopsy, the patient had an active staphylococcal bacteremia. There are reports that postulate that staphylococcal antigens drive activation of immune system and in consequence, could cause this rare form of IgA-dominant glomerulonephritis with cryoglobulinemic features. After ruling out other causes of cryoglobulinemia, we discuss a plausible causal relationship of the staphylococcal infection in the pathogenesis of CryoGN in our patient.

Detectable serum IgM monoclonal gammopathy in non-hepatitis-associated mixed cryoglobulinemic glomerulonephritis: A case report and literature review

Cryoglobulinemia is the presence of circulating cryoglobulin which can cause systemic vasculitis and glomerulonephritis. Monoclonal gammopathy of renal significance is strongly associated with type I cryoglobulinemia, but the role of detectable serum monoclonal gammopathy in mixed (type II) cryoglobulinemia is not clearly established. We report a case of a 71-year-old woman who presented with skin rash, leg edema, and azotemia. Investigations showed a positive result for rheumatoid factor, low complement C4 level, positive result for serum cryoglobulin, and positive M-spike on serum protein electrophoresis and IgM kappa monoclonal gammopathy on serum immunofixation. Kidney biopsy revealed membranoproliferative glomerulonephritis, polytypic IgM-dominant deposits in an immunofluorescence study, and microtubular substructures in an electron microscopic study. After an extensive workup, no evidence of myeloma or lymphoma was found. A diagnosis of monoclonal gammopathy of renal significance-associated mixed cryoglobulinemic glomerulonephritis was made. Due to the detectable IgM kappa monoclonal gammopathy in the patient's serum, clonal-directed therapy was administered. The patient had been in clinical remission after treatment with clone-directed therapy with cyclophosphamide and steroids. The literature review for cases of type II cryoglobulinemic glomerulonephritis that have detectable serum monoclonal gammopathy are summarized in this study.

Recognizing the true face of noninfectious cryoglobulinemic glomerulonephritis

Cryoglobulinemia encompasses a group of diseases with circulating aberrant Igs, which can cause systemic cryoglobulinemic vasculitis, including cryoglobulinemic glomerulonephritis. The complexities of different types and changing etiologies of cryoglobulinemias determine its heterogeneous clinical manifestations and diagnostic difficulties. In this issue of Kidney International, Javaugue et al. have emphasized the diagnostic points of cryoglobulinemic glomerulonephritis and hematological disorders as the major culprits of noninfectious cryoglobulinemic glomerulonephritis in a large cohort.