Cryoglobulinemia Type II: Sustained Remission After B-Cell–Directed Therapy

Introduction

Cryoglobulinemia is a rare disease with a prevalence of <5 cases per 10 000 population [1]. Robust epidemiological studies are lacking. In many cases there is significant diagnostic delay leading to years of morbidity.

Cryoglobulins are proteins that precipitate in plasma at temperatures <37°C and dissolve upon reheating to 37°C. They consist of immunoglobulins (Ig) in combination with complement components or immunoglobulins alone. Cryoglobulins are commonly classified into 3 types according to the Brouet criteria [2]. Type I cryoglobulins consist of monoclonal immunoglobulins, and are always associated with an underlying monoclonal B-cell disorder such as monoclonal gammopathy of clinical significance (MGCS), Waldenström macroglobulinemia, non-Hodgkin lymphoma, chronic lymphocytic leukemia (CLL), or multiple myeloma [3]. Type II cryoglobulins are a mixture of monoclonal IgM with rheumatoid factor activity and polyclonal IgG, and are associated with autoimmune diseases (systemic lupus erythematosus [SLE] and Sjögren syndrome), lymphoproliferative disorders or infection (particularly hepatitis C virus infection). Type III cryoglobulins consist of polyclonal IgM with rheumatoid factor activity and polyclonal IgG, and are associated with infection or autoimmune diseases.

Clinical disease manifests when cryoglobulins precipitate and deposit in small and medium-sized blood vessels, causing vascular obstruction or vasculitis [4]. This can lead to an array of end-organ damage encompassing the skin, kidneys, gastrointestinal tract, and nervous system. Presenting symptoms classically include palpable purpura, skin ulcers, membranoproliferative glomerulonephritis, peripheral neuropathy, constitutional symptoms, arthralgia, and Raynaud’s phenomenon.

At present, there is no consensus on first-line treatment for non-infectious type II cryoglobulinemia. Therapy based on the monoclonal anti-CD20 antibody rituximab in combination with glucocorticosteroids is the preferred choice in many centers [4–6]. Rituximab targets B cells presenting the surface antigen CD20, leading to selective depletion of these cells by triggering several cytotoxic pathways. The main mechanisms are complement-mediated cell death, apoptosis, and macrophage recognition leading to phagocytosis. Glucocorticosteroids suppress B-cell proliferation and differentiation into immunoglobulin-producing B cells. Regimens combining rituximab and glucocorticosteroids induces clinical remission in two-thirds of patients [7]. However, about 10% of patients are refractory to rituximab [6], and one-third of the initially-responding patients experience relapse within the first year [6,8]. Predictors of early relapse are skin and articular involvement, as well as failure to achieve complete immunological response within the first 12 months of therapy [8]. This indicates that the depth of response is important. However, many reports on treatment outcomes focused primarily on clinical response. Outcomes for immunological or hematological response are infrequently reported. Patients who achieve an initial clinical response can still have residual antibody-producing B cells, quickly leading to relapse.

Our center has extensive experience with treating diseases caused by monoclonal IgM produced by clonal B cells with B-cell–targeting therapy combining rituximab with potent chemotherapeutic agents [9–11]. Applying this strategy, we report the clinical course of 2 patients with non-infectious type II cryoglobulinemia who achieved sustained clinical and hematological remissions. The treatment was well tolerated, and may have led to cure.

Case Reports

CASE 1:

A 43-year-old woman with a history of spontaneous abortion and hysterectomy due to endometriosis presented in 1997 with a protracted flu-like illness from which she did not fully recover. The following year she developed Raynaud’s phenomenon, palpable purpura on her extremities, and renal impairment with nephrotic proteinuria. A renal biopsy was performed, showing membranoproliferative glomerulonephritis. Hypocomplementemia, monoclonal IgM kappa, and a small clonal B lymphocyte population in bone marrow were disclosed. At that time, the clonal B lymphocyte population and the monoclonal gammopathy were not considered significant.

Her symptoms resolved with a course of prednisolone, but quickly relapsed after tapering. Further, monthly pulses of intravenous cyclophosphamide showed no clinical effect and therapy was discontinued after 6 months. A second renal biopsy at this time showed vasculitis-associated mesangio-proliferative glomerulonephritis. Importantly, there were no immune complex depositions in the glomeruli.

Despite maintenance therapy with azathioprine 100 mg daily and a small dose of prednisolone, her symptoms gradually exacerbated over the next few years to include fatigue, arthralgias, sicca symptoms, sunlight intolerance, and Raynaud’s phenomenon. She periodically had palpable purpura on her ankles. The clinical presentation included features resembling Sjögren’s disease, SLE, or small vessel vasculitis, but a definitive diagnosis was not established. Serology was negative for anti-nuclear antibodies (ANA), antineutrophil cytoplasmic antibodies (ANCA), and antiphospholipid antibodies. Laboratory findings revealed a slightly elevated erythrocyte sedimentation rate (ESR) of 34 mm/h [ref. 3–20] and a decreased complement C4 at 0.02 g/L [ref. 0.1–0.4]. A tentative diagnosis of undifferentiated connective tissue disease (UCTD) was made. Therapy with azathioprine and low-dose prednisolone (7.5–20 mg daily) was continued for the next 6 years, with regular follow-up visits.

In 2003 her symptoms significantly worsened over the course of a few weeks. She experienced profound malaise, with peripheral pitting edema and painful ulcerations on her hands and lower extremities. A skin biopsy showed depositions in the vessel walls of immunoglobulins, complement and fibrin, suggestive of leukocytoclastic vasculitis. At this time, cryoglobulins (3+) were detected. Plasma protein electrophoresis identified a monoclonal IgM kappa; total IgM 6.67 g/L. Hepatitis C serology was negative.

Due to her increased symptom burden, she was admitted to the rheumatology ward and received 3 boluses of i.v. methylprednisolone 750 mg, in addition to an increased dose of azathioprine. She experienced incomplete symptom relief. A bone marrow biopsy was performed, showing a low-grade malignant B-cell lymphoma, not otherwise classified (Figure 1). In late 2003, 6 years after her initial symptoms, a diagnosis of lymphoproliferative disease with type II cryoglobulinaemia was finally made.

As she had failed to achieve lasting symptom relief on immunosuppressants alone, a novel strategy was attempted. The intention was to target the underlying B-cell clone responsible for the production of disease-inducing monoclonal immunoglobulins using a protocol developed for cold agglutinin disease aiming at a complete haematological remission [9]. With the patient’s informed consent, therapy was initiated consisting of 4 cycles of fludarabine 35 mg/m2 p.o. on days 1 to 5 and rituximab 375 mg/m2 i.v. on day 1, at 4-week intervals. She tolerated the treatment well, with no significant adverse events and no need for hospitalization.

The patient experienced rapid and enduring symptom relief. After the first treatment cycle, her skin ulcerations had resolved completely, and the monoclonal IgM and cryoglobulins were no longer detectable. After 4 treatment cycles, no residual clonal B cells could be identified in the bone marrow. Complete hematological remission was achieved, which as of February 2025 has been sustained for 21 years.

CASE 2:

A 62-year-old man with a mechanical aortic valve and atrial fibrillation presented with ankle edema and confluent exanthemas (macular purpura) involving his back and lower extremities. Blood tests revealed elevated CRP of 110 mg/L (ref. <4 mg/L) and ESR of 25 mm/h (ref. 1–12 mm/h). There was no evidence of infection, including negative serology for hepatitis C. The exanthemas spontaneously resolved after 5 days, but reappeared persistently every 5 to 6 weeks accompanied by arthralgias of the ankles and knees as well as myalgia. Cutaneous vasculitis was suspected, and a skin biopsy showed mild perivascular inflammation and extravasation of erythrocytes. No monoclonal component was detected. The cryoglobulin test result was negative. ANA, ANCA, and antibodies against cyclic citrullinated peptide (anti-CCP) were all negative. Complement C4 was reduced 0.05 g/L (ref. 0.10–0.50). Rheumatoid factor latex IgM in plasma was elevated 359 IU/mL (ref. 0–24 IU/mL).

Three years after his initial symptoms appeared, a small monoclonal component was identified in plasma – IgM kappa 0.5 g/L. A bone marrow smear was considered unremarkable. A skin biopsy showed necrotizing vasculitis with subacute inflammation with no B- or T-cell clonality, and immunofluorescence was normal. A cryoglobulin test was positive (2+), but a repeat test was negative. This is not uncommon, as a reliable cryoglobulin test result is dependent on correct handling and processing of the sample.

The patient received a tentative diagnosis of Schnitzler syndrome; an autoinflammatory disease characterized by monoclonal IgM and urticarial rash. Therapy with anakinra 100 mg s.c. daily was initiated without any clear response, and he continued to experience flares of exanthemas on his lower extremities.

Over the next couple of years, he gradually developed symptoms of polyneuropathy with increasing loss of sensation in his feet. At this point a renewed diagnostic workup was performed. A broad blood panel was taken, including a third cryoglobulin test, which was positive (2+). The bone marrow biopsy was reported to be normal, but a very small B-cell clone was disclosed by flow cytometry. Based on the positive cryoglobulin assay and the presence of a small B-cell clone, a diagnosis of type II cryoglobulinemia was made 5 years after the onset of his initial symptoms.

As in the first case, a potent B-cell–directed therapy was initiated, aiming to achieve complete hematological remission, not merely clinical response. Once again, a protocol proven effective in treatment of chronic cold agglutinin disease was chosen [10]. Following informed consent, therapy consisting of 4 cycles of bendamustine 90 mg/m2 i.v. on days 1 and 2, with rituximab 375 mg/m2 i.v. on day 1 at 4-week intervals was administered. He tolerated the treatment well, with no significant adverse events. Follow-up blood tests between treatment cycles did not disclose any clinically significant cytopenias, and there was no need for blood transfusions, platelet transfusions, or antibiotics. Already after 1 cycle of bendamustine and rituximab, the exanthemas improved. He did not experience any more flares of exanthemas after initiation of treatment.

The patient achieved a complete clinical and haematological remission after 4 cycles of bendamustine and rituximab. Response evaluation by flow cytometry of bone marrow aspirate did not detect any residual clonal B cells, and monoclonal IgM was no longer detected by plasma protein electrophoresis. Over the next years, he reported improvement of polyneuropathy as well as absence of exanthema and arthralgia. He is still in complete remission 10 years after treatment.

Discussion

Cryoglobulinaemia is a rare, and probably underreported, disease that can confer significant morbidity. There is often diagnostic delay owing to the disease’s rarity, generalized nature of symptoms, and errors in diagnostic sampling and handling. Enhancing clinicians’ awareness is a key step in identifying these patients. A positive rheumatoid factor IgM test and a low complement C4 level may raise suspicion of cryoglobulinemic vasculitis. The definitive test for cryoglobulinemia is demonstrating cryoglobulins in blood. As cryoglobulins precipitate in temperatures below 37°C, it is essential that the sample is handled above this temperature. Failing to do so can result in a false-negative test result. If clinical suspicion is high, repeating the test is warranted.

There is currently no consensus for treatment of patients with non-infectious type II cryoglobulinemia, and commonly-used strategies are based on combinations of glucocorticosteroids, immunosuppressants, rituximab, and plasma exchange [12]. Rituximab with or without glucocorticosteroids seems to be the preferred first-line treatment [4]. However, many patients either fail to respond or experience early relapses [6,8]. Infectious complications have been prominent, particularly after administration of rituximab with glucocorticosteroids [5]. Long-term adverse effects of rituximab include B lymphocyte depletion, delayed-onset neutropenia, and hypogammaglobulinemia, all increasing the risk of serious infections. The level of evidence for treatment of non-infectious cryoglobulinaemia is low, with no randomized controlled trials to support clinical decision-making. As the disease is rare and presumably underreported, randomized prospective clinical studies will be difficult to perform, and decision-making regarding treatment will probably need to rely on clinical expertise and observational data.

This small case series concerns 2 patients with type II cryoglobulinaemia who achieved deep and very long-lasting remissions after treatment with more potent B-cell–directed therapy than is the current standard of care. We have extensive experience from treating patients with cold agglutinin disease; a disease with many similarities to cryoglobulinaemia [13]. In a prospective study on chronic cold agglutinin disease, rituximab monotherapy was effective in approximately 50% of patients, but the response duration was short and complete hematological remission was rare [14]. By combining rituximab with fludarabine or bendamustine the response rate improved considerably, and most of the responding patients achieved a complete hematological response, translating to long-lasting clinical remission and possibly cure [9–11]. These 2 patients with non-infectious type II cryoglobulinaemia were successfully treated using to 2 different treatment protocols for cold agglutinin disease. The therapy was well tolerated with no adverse events, and led to sustained clinical and hematological remission in both patients. This treatment strategy targets the underlying B-cell clone producing the cryoglobulins, and aims to remove the source of disease instead of merely alleviating symptoms. Achieving a complete hematological response will likely result in a sustained clinical remission in most patients.

Conclusions

We hope that by highlighting this rare, but very treatable disease, we can encourage clinicians to consider cryoglobulinemia as a differential diagnosis. Further, we hope this case series encourages treating this population with more specific and potent B-cell–targeting therapy.