Cryofibrinogen-Associated Glomerulonephritis

Discontinuing Hemodialysis through Corticosteroid Treatment in a Patient with Cryofibrinogen-associated Glomerulonephritis

Cryofibrinogen-associated glomerulonephritis (CryoFiGN) is rare, and its diagnosis is difficult while treatment is not established. We herein report an elderly woman with CryoFiGN who experienced recurrent purpura and nephritic features that subsequently progressed to nephrotic syndrome and required hemodialysis during the 18-month clinical course. The patient was treated with corticosteroids, which led to the discontinuation of hemodialysis. The diagnosis of CryoFiGN was based on the clinical presentation, characteristic glomerular deposits, and results of laser microdissection and liquid chromatography-tandem mass spectrometry of the glomeruli. This case highlights the potential utility of corticosteroids as a treatment option for patients with CryoFiGN, even after hemodialysis.

Cryoglobulinemic Vasculitis in Disguise: Cryofibrinogenemia as Variant of Monoclonal Gammopathy of Renal Significance

Monoclonal gammopathy with cryoactivity (ie, cryoglobulins) that causes glomerulonephritis is considered within the spectrum of monoclonal gammopathy of renal significance. Cryofibrinogenemia (cryoactivity of coagulation factors) is very rarely associated with glomerulonephritis. We present a 39-year-old woman with a relapsing nephrotic syndrome. Laboratory investigation detected cryofibrinogen; the precipitate consisted of fibrinogen and a monoclonal immunoglobulin (M-protein; IgG-λ), and the latter was also detected in serum (4g/L). Initial conventional immunosuppressive therapy resulted in temporary renal remission. In view of the M-protein, subsequent therapy consisted of bortezomib/dexamethasone and high-dose melphalan followed by autologous hematopoietic stem cell transplantation, and resulted in a very good partial hematological response and temporary renal remission. However, after hematological and renal relapse, we performed unique experiments to clarify the role of the M-protein. Mixing patient serum with donor plasma resulted in cryoactivity, composed of M-protein+fibrinogen. Patient plasma deprived of M-protein did not have cryoactivity. Therefore, cryoactivity was dependent on the M-protein. We started lenalidomide, which resulted in very good partial hematological and renal remission. Thus, cryofibrinogenemia can be the consequence of an M-protein, which we suggest should be defined as monoclonal gammopathy of renal significance.

Cryofibrinogenemia: What Rheumatologists Should Know

Cryofibrinogenemia refers to the presence of cryofibrinogen in plasma. This protein has the property of precipitating at lower temperatures. Cryofibrinogenemia is a rare disorder, clinically characterized by skin lesions, such as ulcers, necrosis, livedo reticularis, arthralgia, thrombosis, and limb ischemia. These features are most often observed in rheumatological practice and consist in the differential diagnoses of antiphospholipid syndrome, primary vasculitis, thrombotic thrombocytopenic purpura, and cryoglobulinemia. Classical histopathological findings include the presence of thrombi within the lumen of blood vessels of the skin without vasculitis. To date, there are no validated classification criteria. Management includes corticosteroids, immunosuppressive therapy, anticoagulants, and fibrinolytic agents. This narrative review aims to make physicians, particularly rheumatologists, aware of existence of this underdiagnosed condition. There are no epidemiological studies evaluating the prevalence of cryofibrinogenemia in different rheumatological disorders. Studies are also required to investigate if certain features of rheumatological diseases are related to the presence of cryofibrinogenemia.

Renal Disease in Cryoglobulinemia

Background

Renal disease in cryoglobulinemia is difficult to grasp and diagnose because it is rare, serological testing is challenging and prone to artifacts, and its morphology is shared by other renal diseases resulting in a spectrum of differential diagnoses. On occasion, a definitive diagnosis cannot even be rendered after immunofluorescence and electron microscopic studies.

Summary

Based on kidney biopsies seen in our routine diagnostic and referral practice, we discuss and illustrate various morphological patterns of renal injury associated with cryoglobulins. We outline key pathophysiologic and clinical aspects associated with cryoglobulinemia induced renal disease and describe morphologic changes with a focus on electron microscopy. We present our practical, morphology-based approach to diagnostic decision-making with special consideration of differential diagnoses and disease mimickers. Since cryoglobulins are rarely tested for prior to kidney biopsy, pathologists and clinicians alike must have a high level of suspicion when interpreting renal biopsies and managing patients.

Key Messages

Cryoglobulinemia-associated glomerulonephritis (GN) is a multifactorial disease which is important to recognize for clinical practice. Morphological features suggestive of cryoglobulinemia-associated GN include a pattern of membranoproliferative GN with abundance of monocytes and the presence of (pseudo)thrombi. By electron microscopy, the main diagnostic features are a prominent infiltration of monocytes/macrophages and the presence of mesangial and subendothelial deposits with frequently curved microtubular/cylindrical and annular substructures.

Immunotactoid glomerulonephritis in a patient with cold agglutinins: causal association or mere coincidence?

We report a case of immunotactoid glomerulonephritis (ITG) in a patient with cold agglutinins. An 86-year-old Japanese male with a history of hypertension, dyslipidemia, and gastric malignancy presented to our hospital for the evaluation of proteinuria and hematuria. He had an elevated blood pressure of 200/77 mmHg and edema of the lower extremities. Initial blood test results revealed an impaired renal function (creatinine, 1.37 mg/dL) and hypoalbuminemia (albumin, 2.6 g/dL). His estimated daily urinary protein was 5.89 g/g creatinine, meeting the diagnostic criteria for nephrotic syndrome. The selectivity index for proteinuria indicated low selectivity (0.329). We conducted a renal biopsy to identify the cause of nephrotic syndrome. Immunofluorescence microscopy demonstrated positive staining of IgM, C4, and C1q. Electron microscopy exhibited mesangial expansion with inflammatory cells and a lobular structure, suggesting membranoproliferative glomerulonephritis. Subendothelial deposits containing microtubular structures with a diameter of approximately 30-200 nm were found, concurrent with the criteria for the diagnosis of ITG. Screening for lymphoproliferative diseases and immunological abnormalities revealed a positive direct Coombs test result and the presence of cold agglutinins. Paraproteinemia was absent. The similarities between cold agglutinin disease and ITG, including the production of autoantibodies and involvement of complement pathways, raise the possibility that cold agglutinins played a role in the development of ITG; however, we were unable to prove it due to difficulties in detecting cold agglutinins on renal histology. We discuss the possible implications for pathogenesis considering prior reports on nephrotic syndrome being potentially associated with cold agglutinins.

Characteristic electron-microscopic features of cryofibrinogen-associated glomerulonephritis: a case report

Background

Cryofibrinogenemia is a rare disorder that mainly affects the skin and occasionally the kidney. However, there are few published reports of cryofibrinogenemia-associated renal pathology. We therefore report a patient with cryofibrinogen-associated glomerulonephritis. Samples from this patient were examined by electron microscopy, laser microdissection, and liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Case presentation

A 78-year-old Japanese man presented with declining renal function, proteinuria, and gross hematuria. Kidney biopsy showed a membranoproliferative pattern with crescent formation and dominant C3c deposition in which subendothelial deposits with uniquely organized electron-microscopic features were observed. Additional ultrastructural analysis of cryoprecipitates extracted from plasma revealed similar structures of the glomerular subendothelial deposits. LC-MS/MS identified an increase in fibrinogen α, β, and γ chains, fibronectin, filamin-A, and C3. The glomerular lesions were diagnosed as cryofibrinogen-associated glomerulonephritis on the basis of these findings.

Conclusions

Although there are few reports of cryofibrinogen-associated glomerulonephritis, we believe that accurate diagnosis can be achieved by performing LC-MS/MS and ultrastructural analysis.