RARE DISEASE
Schnitzler syndrome
Schnitzler syndrome
Schnitzler syndrome
Synonyms: Chronic urticaria with gammopathy, Chronic urticaria with macroglobulinemia
Synonyms: Chronic urticaria with gammopathy, Chronic urticaria with macroglobulinemia
Synonyms: Chronic urticaria with gammopathy, Chronic urticaria with macroglobulinemia
Drug discovery
2
drugs
With orphan designations
Overview
Schnitzler syndrome is a rare autoinflammatory disorder characterized by chronic nonpruritic urticaria, monoclonal gammopathy (typically IgMκ), and systemic inflammation. Key features include recurrent fever, arthralgia, bone pain, fatigue, and elevated inflammatory markers. Diagnosis is often delayed (median 5 years) due to under-recognition. Pathogenesis involves IL-1 dysregulation, making IL-1 inhibitors (e.g., anakinra) highly effective. Long-term risks include AA amyloidosis and lymphoproliferative disorders (e.g., lymphoma) in 8–20% of cases [1][2][6][12].
Burden
Morbidity: Chronic symptoms (rash, fever, pain) severely impact quality of life; untreated cases risk AA amyloidosis [4][9][12].
Diagnostic delay: Median 5 years, leading to prolonged suffering and irreversible complications (e.g., joint damage) [1][8][9].
Progression: 8–20% develop lymphoproliferative disorders; median survival >12.8 years with treatment [1][6][12].
Therapies
First-line: IL-1 blockade (anakinra) induces rapid, sustained symptom remission [1][5][11].
Alternatives: Colchicine for mild cases, IL-1β inhibitors (canakinumab), or Bruton tyrosine kinase inhibitors (ibrutinib) [3][7][14].
Avoid corticosteroids/immunosuppressants due to limited efficacy and side effects [5][15].
Categories: rare systemic and rheumatological diseases
Research Papers
198 drug discovery papers about Schnitzler syndrome, with 1 first-in-class and 1 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
198 drug discovery papers about Schnitzler syndrome, with 1 first-in-class and 1 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
small molecules
2026-04-11 | The Role of Corticosteroid Therapy in Schnitzler Syndrome: A Case Report
Background: Urticaria is a common inflammatory mucocutaneous syndrome with multiple etiologies. When recalcitrant to standard antihistamine therapy, a systematic diagnostic workup is essential to identify rare underlying systemic conditions such as Schnitzler Syndrome. Case Presentation: We report the case of a 41-year-old woman with a background of chronic asthma, fibromyalgia, degenerative retinopathy, and nasal polyposis, who presented with an 8-month history of recalcitrant urticarial eruption. Despite sequential trials of multiple antihistamine regimens including cetirizine, hydroxyzine, loratadine, levocetirizine, desloratadine, montelukast, and bilastine at standard and quadruple doses no clinical improvement was observed. Extensive etiological workup excluded common chronic urticaria, drug-induced, infectious, inducible, and autoimmune causes, as well as urticarial vasculitis, Adult-onset Still's disease, systemic lupus erythematosus, and Cryopyrin-Associated Periodic Syndromes (CAPS). Serum protein electrophoresis revealed a monoclonal peak in the gamma-globulin zone, confirmed by immunofixation as monoclonal IgG elevation, establishing the diagnosis of Schnitzler Syndrome. Treatment and Outcome: The patient was initiated on corticosteroid therapy with prednisolone 40 mg/day for 3 months, resulting in marked clinical improvement. Conclusion: This case highlights the importance of a thorough diagnostic approach in chronic recalcitrant urticaria. While antihistamines remain the first-line treatment, corticosteroid therapy may play a critical role in antihistamine-refractory forms, particularly in the context of Schnitzler Syndrome. Clinicians should consider monoclonal gammopathy screening in patients with persistent urticaria unresponsive to standard therapy.
2026-04-06 | Bruton protein-tyrosine kinase (BTK) FDA-approved small molecule inhibitors used for the management of neoplastic and inflammatory disorders.
The Bruton nonreceptor protein-tyrosine kinase (BTK) plays a central role in B cell antigen receptor signaling. Following B cell receptor activation, the Src protein kinase Lyn and the spleen protein kinase (Syk) activate BTK. It then mediates the phosphorylation and activation of phospholipase Cγ2 (PLCγ2). The Ras/RAF/MEK/ERK and NF-κB pathways are downstream of PLCγ2. These signaling modules participate in the affinity maturation of antibody-producing B cells by somatic hypermutation. The absence of BTK results in X-linked agammaglobulinemia. BTK contains an amino-terminal PH (pleckstrin homology) domain that interacts with phosphatidyl inositol trisphosphate within the plasma membrane to promote its membrane association. This is followed by a TEC homology segment, an SH3 and SH2 domain, and finally a carboxyterminal protein kinase domain. Aberrant B cell receptor signaling occurs in several B cell neoplasms including follicular lymphoma (treated with zanubrutinib, a BTK inhibitor), mantle cell lymphoma (acalabrutinib, pirtobrutinib, zanubrutinib), marginal zone lymphoma (zanubrutinib), chronic lymphocytic leukemia and small lymphocytic lymphoma (ibrutinib, acalabrutinib, zanubrutinib, pirtobrutinib), and Waldenström macroglobulinemia (ibrutinib, zanubrutinib). Chronic spontaneous urticaria and chronic immune thrombocytopenia are driven by B cell dysfunction. The former is treated with remibrutinib and the latter is treated with rilzabrutinib, both of which inhibit BTK. Four drugs (ibrutinib, acalabrutinib, zanubrutinib, remibrutinib) form an irreversible covalent bond and rilzabrutinib forms a reversible covalent bond with BTK Cys481. Pirtobrutinib fails to form a covalent bond and is a reversible BTK inhibitor. The FDA-approvals of rilzabrutinib and remibrutinib (2025) represent the first nononcologic authorizations for BTK antagonists.
2026-01-18 | Schnitzler’s syndrome, an underdiagnosed autoinflammatory disease: current and future perspective
Schnitzler’s syndrome is a rare but usually underdiagnosed autoinflammatory disease, characterized by monoclonal IgM gammopathy, persistent urticaria, intermittent fever, bone pain, and arthralgia or arthritis. Although first reported by Dr. Liliane Schnitzler in 1972, the syndrome continues to pose challenges in diagnosis, and it usually takes more than five years before it is properly identified. Disorders show up in a form of urticaria, arthritis, organomegaly, fever, lymphadenopathy, high ESR, leukocytosis, and bone pain. Central to its pathogenesis are immunologic perturbations and activation of the inflammasome. It is typically diagnosed through clinical exam with history and important feature identification such as monoclonal gammopathy and acute or relapsing urticarial rash. Therapeutically synthetic agents include anakinra, canakinumab, rilonacept, and anti-IL-6 have been used with variable success. Recent research also demonstrated how natural treatments such as Terminalia chebula, Emblica offcinalis, Schinus terebinthifolia, tulsi, asafoetida, and Wedelia plants have the potential for controlling the symptoms and changing inflammatory paths. Promising medicinal possibilities for these plants, according to in silico investigations, point to further research into their clinical uses. With new therapy paths that promise better patient outcomes, Schnitzler’s illness is overall a therapeutic challenge.
2025-11-13 | A rare complication in Schnitzler syndrome: recall urticaria in a patient treated with anakinra—a case report
Schnitzler syndrome is a rare acquired autoinflammatory disorder defined by a chronic urticarial rash, monoclonal IgM (or IgG) gammopathy, and systemic features including fever, arthralgia, and elevated inflammatory markers. Interleukin-1 blockade with anakinra is the current treatment of choice. We report the case of a 75-year-old woman who, after seven years of misdiagnosis as chronic spontaneous urticaria, fulfilled the Strasbourg Criteria for Schnitzler syndrome. Treatment with anakinra induced rapid clinical improvement but was complicated by the onset of recall urticaria (RU), characterized by delayed giant wheals at both current and previous injection sites. Laboratory findings suggested an inflammatory response, and the reaction was managed with corticosteroids and antihistamines, followed by colchicine, which achieved stable disease control. RU is a rare hypersensitivity phenomenon previously described with immunotherapy, heparin, NSAIDs, and other biologics, but to our knowledge, this is the first report associated with anakinra. This case broadens the spectrum of anakinra-related adverse effects and highlights the need for further investigation into the immunopathogenesis of RU.
2025-05-28 | A case of Schnitzler syndrome complicated by rheumatoid arthritis treated with methotrexate.
Schnitzler syndrome (SchS) is a rare autoinflammatory disorder characterised by recurrent urticaria, monoclonal gammopathy, fever, and arthralgia. We herein report a case of SchS complicated by rheumatoid arthritis (RA). A 78-year-old man presented to our hospital with fever, myalgia, and urticaria, each lasting for ~1 week over the past 8 years. He was diagnosed with SchS based on monoclonal immunoglobulin G gammopathy, chronic urticaria, an intermittent fever, arthritis, high inflammatory markers, and neutrophil infiltration in the dermis on skin biopsy. Although colchicine improved the symptoms slightly, the patient subsequently developed arthritis and was diagnosed with RA based on elevated anti-cyclic citrullinated peptide antibody and rheumatoid factor levels. Methotrexate (MTX), a first-line therapy for RA, was initiated, resulting in a remarkable improvement in both RA and SchS symptoms. This case highlights the rare coexistence of SchS and RA as well as the efficacy of MTX in treating both conditions. Although interleukin (IL)-1 inhibitors are considered the most effective treatment for SchS, they are not approved for SchS in Japan and are expensive. The efficacy of IL-6 inhibitors in SchS has also been reported, and MTX suppresses inflammatory cytokines, including IL-1 and IL-6. As shown in our case, drugs that modulate IL-6 levels, such as MTX, may be a viable treatment option for SchS.
antibodies
2026-05-28 | Monoclonal gammopathy–associated autoinflammation: A systematic review and meta-analysis of Schnitzler syndrome.
e19579 Background: Schnitzler syndrome is a rare, underdiagnosed disorder that usually presents with late-onset systemic inflammation and monoclonal gammopathy. Key clinical findings include chronic urticarial rash, fever, bone pain, and lymphadenopathy. Given that most data regarding this rare disease are derived from small observational studies, this study aims to systematically characterize the demographic, clinical, laboratory, and treatment outcomes of patients with Schnitzler syndrome. Methods: A thorough literature search of the PubMed, Scopus, and Web of Science databases was performed in September 2025. Data on medical history, presentations, complications, diagnostics, treatment patterns, and outcomes were obtained. Results: This pooled analysis includes 187 articles reporting 243 individual cases of Schnitzler syndrome over the years 1989–2025. The mean patient age was 57.4 years ±12.2 with a male-to-female ratio of 1.32:1, indicating a slight male predominance. The most frequently reported manifestations were chronic urticarial rash (226/243, 93.0%), fever (194/243, 79.8%), and arthralgia (145/243, 59.7%), with lymphoid involvement mainly manifesting as lymphadenopathy (63/243, 25.9%); progression to lymphoproliferative disorders was rare (15/243, 6.2%). Most patients presented with an IgM gammopathy (193/243, 79.4%), confirming IgM as the predominant class. In a smaller subset, IgG (26/243, 10.7%) and IgA (3/243, 1.2%) gammopathy was present. Regarding light chain type, kappa predominated (162/243, 66.7%), with fewer cases of lambda (22/243, 9.1%). When stratified by immunoglobulin class, age differed significantly between patients with IgM and IgG gammopathy (58.5 vs 50.8 years, p = 0.015). IL-1 inhibitors were frequently used, with 124/243 patients receiving this therapy (51.0%). Corticosteroids of various formulations were administered in 154/243 patients (63.4%). Treatment response was favorable in most patients, with 126/243 achieving a complete clinical response (51.9%) and 47/243 a partial response (19.3%). Sixteen patients showed no response (6.6%). On multivariate analysis, IL-1 inhibitor use was independently associated with higher odds of complete response (OR 7.89; 95% CI 1.70–36.65). In the minority of patients who relapsed after an initial response to IL-1 inhibitors due to treatment discontinuation or tapering, the addition of corticosteroids restored the response. Conclusions: Schnitzler syndrome is a rare autoinflammatory condition predominantly affecting older males, characterized by chronic urticaria, fever, and IgM kappa gammopathy. While IL-1 inhibitors and corticosteroids offer high rates of clinical response, the frequent relapse upon tapering underscores the need for long-term maintenance. Studies are needed to explore if anti-plasma cell therapy would decrease relapse and induce long-term remission.
2026-05-22 | Cutaneous diseases caused by monoclonal immunoglobulin and/or free light chains (monoclonal gammopathy of cutaneous significance).
Monoclonal immunoglobulin (M-Ig) and/or free light chains (FLC) can cause a wide range of organ and tissue damage. The most common are various forms of nephropathies, for which the term monoclonal gammopathy of renal significance was created, and a morphological classification was proposed by the "International Kidney and Monoclonal Gammopathy Research Group." Another large group consists of clinical entities where, among other things, various forms of skin damage occur. For these, the group designation monoclonal gammopathy of cutaneous significance was created. Although the etiopathogenesis is hematologic, the symptoms lead patients with this form of monoclonal gammopathy-related damage to dermatology clinics. Dermatological publications from the last 5 years distinguish diseases with a clearly expressed etiopathogenetic connection to monoclonal gammopathy, defining a total of 12, and then mention other diseases in which the etiopathogenetic relationship is less clear. The group of skin diseases with a clearly demonstrated connection to monoclonal gammopathy includes: AL amyloidosis of the skin, cutaneous macroglobulinemia, skin changes in POEMS syndrome, scleromyxedema, scleroderma, diffuse normolipidemic xanthomas, necrobiotic xanthogranuloma, urticaria in Schnitzler syndrome, telangiectasia in TEMPI syndrome, localized erythema in AESOP syndrome, cryoglobulinemic skin changes, cutis laxa (loose skin). Among the diseases with a less clear connection to monoclonal immunoglobulin, we mention IgA pemphigus. The text provides brief descriptions supplemented with imaging documentation of cases we have encountered over the past 35 years. If a dermatologist encounters the mentioned diseases, they should examine M-Ig and FLC, and in the case of a positive finding, consult with a hematologist regarding the possibility of targeted therapy.
2026-01-22 | [No mistakes with Schnitzler syndrome].
Schnitzler syndrome is a rare autoinflammatory disease that primarily manifests in adulthood. In cases presenting with chronic urticaria and paraproteinemia, Schnitzler syndrome should be considered in the differential diagnosis, and the Strassburg criteria should be applied to establish the diagnosis. IL-1 inhibitors have proven to be an effective long-term treatment for Schnitzler syndrome. Patients should be moni-tored for the potential development of lymphoproliferative disorders and/or amyloidosis.
2025-07-01 | Unexplained fever and rash: a case of Schnitzler syndrome
Abstract Introduction Fever, rash and joint pain are common manifestations of rheumatism. The article reports a patient with recurrent fever and rash, and the final diagnosis of Schnitzler syndrome. The course of diagnosis and treatment was described in detail, and the clinical manifestations, pathogenesis, diagnosis and treatment of the disease were further discussed. Case presentation In this article, we report a 59-year-old man who had recurrent fever, rash, and joint pain for 7 years. Once considered as adult still's disease, anti-neutrophil cytoplasmic antibody-associated vasculitis and systemic inflammatory response syndrome, long term use of hormones and immunosuppressants for treatment, with intermittent attacks, about 15–20 days per occurrence. The interval of rash and fever in the two weeks before admission has shortened, about every 3–5 days. No abnormalities were found in infection, immunity and other related examinations, IgM κ M protein was positive, PET-CT and bone marrow biopsy did not indicate tumor, the patient met the diagnostic criteria for Strasbourg Schnitzler syndrome, and Schnitzler syndrome was finally diagnosed. Result The patient was treated with tocilizumab, a humanized anti-IL-6 receptor antibody, and developed skin allergy. Adjustment for methylprednisolone 8 mg once a day, colchicine 0.5 mg twice a day, tofacitinib 5 mg twice a day, waiting for IL-1 receptor antagonist.
2025-06-10 | Low-level NLRP3 mosaicism in chronic urticarial lesions: extending the phenotypic spectrum of NLRP3-related disorders and therapeutic implications.
Chronic urticarial lesions, a common condition of mostly unknown cause, can occur in immune dysregulation disorders such as hypocomplementaemic urticarial vasculitis syndrome (HUVS), neutrophilic urticarial dermatosis (NUD) and systemic autoinflammatory diseases (SAIDs), including Schnitzler syndrome. To identify the molecular basis of nonpruritic chronic urticarial eruptions in four unrelated patients initially diagnosed with neonatal NUD, Schnitzler syndrome, HUVS or giant-cell arteritis. Conventional next-generation sequencing (NGS) of leucocyte DNA was supplemented with high-depth NGS (> 1500×) to improve the detection of low-level mosaicism in SAID-related genes. Functional assays were performed on recombinant NLRP3 proteins to assess the impact of the identified variations on the nuclear factor-κB (NF-κB) pathway. One patient presented with persistent isolated urticarial lesions since birth, while the other three experienced late-onset skin lesions. In contrast to the initially suspected diagnoses, conventional NGS revealed NLRP3 mosaicism in two patients, with variant allele fractions (VAFs) of 5% and 11%, respectively. In the other two patients, high-depth NGS uncovered NLRP3 mosaicism with VAFs as low as 2-3%. All identified variations activated the NF-κB pathway, demonstrating a gain-of-function effect. Subsequent anti-interleukin-1 therapy led to symptom improvement for all patients. This study highlights the importance of considering NLRP3 mosaicism as an underlying pathological mechanism in chronic urticarial lesions, whether of early or late onset, and whether isolated or mimicking other conditions. As blood contains key target cells for NLRP3 inflammasome activation, even extremely low-level leucocyte mosaicism can be pathogenic. High-depth NGS-based diagnosis of NLRP3-related disorders enables timely initiation of anti-IL-1 therapy, which is crucial to preventing complications such as systemic amyloidosis.
small molecules
2026-04-11 | The Role of Corticosteroid Therapy in Schnitzler Syndrome: A Case Report
Background: Urticaria is a common inflammatory mucocutaneous syndrome with multiple etiologies. When recalcitrant to standard antihistamine therapy, a systematic diagnostic workup is essential to identify rare underlying systemic conditions such as Schnitzler Syndrome. Case Presentation: We report the case of a 41-year-old woman with a background of chronic asthma, fibromyalgia, degenerative retinopathy, and nasal polyposis, who presented with an 8-month history of recalcitrant urticarial eruption. Despite sequential trials of multiple antihistamine regimens including cetirizine, hydroxyzine, loratadine, levocetirizine, desloratadine, montelukast, and bilastine at standard and quadruple doses no clinical improvement was observed. Extensive etiological workup excluded common chronic urticaria, drug-induced, infectious, inducible, and autoimmune causes, as well as urticarial vasculitis, Adult-onset Still's disease, systemic lupus erythematosus, and Cryopyrin-Associated Periodic Syndromes (CAPS). Serum protein electrophoresis revealed a monoclonal peak in the gamma-globulin zone, confirmed by immunofixation as monoclonal IgG elevation, establishing the diagnosis of Schnitzler Syndrome. Treatment and Outcome: The patient was initiated on corticosteroid therapy with prednisolone 40 mg/day for 3 months, resulting in marked clinical improvement. Conclusion: This case highlights the importance of a thorough diagnostic approach in chronic recalcitrant urticaria. While antihistamines remain the first-line treatment, corticosteroid therapy may play a critical role in antihistamine-refractory forms, particularly in the context of Schnitzler Syndrome. Clinicians should consider monoclonal gammopathy screening in patients with persistent urticaria unresponsive to standard therapy.
2026-04-06 | Bruton protein-tyrosine kinase (BTK) FDA-approved small molecule inhibitors used for the management of neoplastic and inflammatory disorders.
The Bruton nonreceptor protein-tyrosine kinase (BTK) plays a central role in B cell antigen receptor signaling. Following B cell receptor activation, the Src protein kinase Lyn and the spleen protein kinase (Syk) activate BTK. It then mediates the phosphorylation and activation of phospholipase Cγ2 (PLCγ2). The Ras/RAF/MEK/ERK and NF-κB pathways are downstream of PLCγ2. These signaling modules participate in the affinity maturation of antibody-producing B cells by somatic hypermutation. The absence of BTK results in X-linked agammaglobulinemia. BTK contains an amino-terminal PH (pleckstrin homology) domain that interacts with phosphatidyl inositol trisphosphate within the plasma membrane to promote its membrane association. This is followed by a TEC homology segment, an SH3 and SH2 domain, and finally a carboxyterminal protein kinase domain. Aberrant B cell receptor signaling occurs in several B cell neoplasms including follicular lymphoma (treated with zanubrutinib, a BTK inhibitor), mantle cell lymphoma (acalabrutinib, pirtobrutinib, zanubrutinib), marginal zone lymphoma (zanubrutinib), chronic lymphocytic leukemia and small lymphocytic lymphoma (ibrutinib, acalabrutinib, zanubrutinib, pirtobrutinib), and Waldenström macroglobulinemia (ibrutinib, zanubrutinib). Chronic spontaneous urticaria and chronic immune thrombocytopenia are driven by B cell dysfunction. The former is treated with remibrutinib and the latter is treated with rilzabrutinib, both of which inhibit BTK. Four drugs (ibrutinib, acalabrutinib, zanubrutinib, remibrutinib) form an irreversible covalent bond and rilzabrutinib forms a reversible covalent bond with BTK Cys481. Pirtobrutinib fails to form a covalent bond and is a reversible BTK inhibitor. The FDA-approvals of rilzabrutinib and remibrutinib (2025) represent the first nononcologic authorizations for BTK antagonists.
2026-01-18 | Schnitzler’s syndrome, an underdiagnosed autoinflammatory disease: current and future perspective
Schnitzler’s syndrome is a rare but usually underdiagnosed autoinflammatory disease, characterized by monoclonal IgM gammopathy, persistent urticaria, intermittent fever, bone pain, and arthralgia or arthritis. Although first reported by Dr. Liliane Schnitzler in 1972, the syndrome continues to pose challenges in diagnosis, and it usually takes more than five years before it is properly identified. Disorders show up in a form of urticaria, arthritis, organomegaly, fever, lymphadenopathy, high ESR, leukocytosis, and bone pain. Central to its pathogenesis are immunologic perturbations and activation of the inflammasome. It is typically diagnosed through clinical exam with history and important feature identification such as monoclonal gammopathy and acute or relapsing urticarial rash. Therapeutically synthetic agents include anakinra, canakinumab, rilonacept, and anti-IL-6 have been used with variable success. Recent research also demonstrated how natural treatments such as Terminalia chebula, Emblica offcinalis, Schinus terebinthifolia, tulsi, asafoetida, and Wedelia plants have the potential for controlling the symptoms and changing inflammatory paths. Promising medicinal possibilities for these plants, according to in silico investigations, point to further research into their clinical uses. With new therapy paths that promise better patient outcomes, Schnitzler’s illness is overall a therapeutic challenge.
2025-11-13 | A rare complication in Schnitzler syndrome: recall urticaria in a patient treated with anakinra—a case report
Schnitzler syndrome is a rare acquired autoinflammatory disorder defined by a chronic urticarial rash, monoclonal IgM (or IgG) gammopathy, and systemic features including fever, arthralgia, and elevated inflammatory markers. Interleukin-1 blockade with anakinra is the current treatment of choice. We report the case of a 75-year-old woman who, after seven years of misdiagnosis as chronic spontaneous urticaria, fulfilled the Strasbourg Criteria for Schnitzler syndrome. Treatment with anakinra induced rapid clinical improvement but was complicated by the onset of recall urticaria (RU), characterized by delayed giant wheals at both current and previous injection sites. Laboratory findings suggested an inflammatory response, and the reaction was managed with corticosteroids and antihistamines, followed by colchicine, which achieved stable disease control. RU is a rare hypersensitivity phenomenon previously described with immunotherapy, heparin, NSAIDs, and other biologics, but to our knowledge, this is the first report associated with anakinra. This case broadens the spectrum of anakinra-related adverse effects and highlights the need for further investigation into the immunopathogenesis of RU.
2025-05-28 | A case of Schnitzler syndrome complicated by rheumatoid arthritis treated with methotrexate.
Schnitzler syndrome (SchS) is a rare autoinflammatory disorder characterised by recurrent urticaria, monoclonal gammopathy, fever, and arthralgia. We herein report a case of SchS complicated by rheumatoid arthritis (RA). A 78-year-old man presented to our hospital with fever, myalgia, and urticaria, each lasting for ~1 week over the past 8 years. He was diagnosed with SchS based on monoclonal immunoglobulin G gammopathy, chronic urticaria, an intermittent fever, arthritis, high inflammatory markers, and neutrophil infiltration in the dermis on skin biopsy. Although colchicine improved the symptoms slightly, the patient subsequently developed arthritis and was diagnosed with RA based on elevated anti-cyclic citrullinated peptide antibody and rheumatoid factor levels. Methotrexate (MTX), a first-line therapy for RA, was initiated, resulting in a remarkable improvement in both RA and SchS symptoms. This case highlights the rare coexistence of SchS and RA as well as the efficacy of MTX in treating both conditions. Although interleukin (IL)-1 inhibitors are considered the most effective treatment for SchS, they are not approved for SchS in Japan and are expensive. The efficacy of IL-6 inhibitors in SchS has also been reported, and MTX suppresses inflammatory cytokines, including IL-1 and IL-6. As shown in our case, drugs that modulate IL-6 levels, such as MTX, may be a viable treatment option for SchS.
antibodies
2026-05-28 | Monoclonal gammopathy–associated autoinflammation: A systematic review and meta-analysis of Schnitzler syndrome.
e19579 Background: Schnitzler syndrome is a rare, underdiagnosed disorder that usually presents with late-onset systemic inflammation and monoclonal gammopathy. Key clinical findings include chronic urticarial rash, fever, bone pain, and lymphadenopathy. Given that most data regarding this rare disease are derived from small observational studies, this study aims to systematically characterize the demographic, clinical, laboratory, and treatment outcomes of patients with Schnitzler syndrome. Methods: A thorough literature search of the PubMed, Scopus, and Web of Science databases was performed in September 2025. Data on medical history, presentations, complications, diagnostics, treatment patterns, and outcomes were obtained. Results: This pooled analysis includes 187 articles reporting 243 individual cases of Schnitzler syndrome over the years 1989–2025. The mean patient age was 57.4 years ±12.2 with a male-to-female ratio of 1.32:1, indicating a slight male predominance. The most frequently reported manifestations were chronic urticarial rash (226/243, 93.0%), fever (194/243, 79.8%), and arthralgia (145/243, 59.7%), with lymphoid involvement mainly manifesting as lymphadenopathy (63/243, 25.9%); progression to lymphoproliferative disorders was rare (15/243, 6.2%). Most patients presented with an IgM gammopathy (193/243, 79.4%), confirming IgM as the predominant class. In a smaller subset, IgG (26/243, 10.7%) and IgA (3/243, 1.2%) gammopathy was present. Regarding light chain type, kappa predominated (162/243, 66.7%), with fewer cases of lambda (22/243, 9.1%). When stratified by immunoglobulin class, age differed significantly between patients with IgM and IgG gammopathy (58.5 vs 50.8 years, p = 0.015). IL-1 inhibitors were frequently used, with 124/243 patients receiving this therapy (51.0%). Corticosteroids of various formulations were administered in 154/243 patients (63.4%). Treatment response was favorable in most patients, with 126/243 achieving a complete clinical response (51.9%) and 47/243 a partial response (19.3%). Sixteen patients showed no response (6.6%). On multivariate analysis, IL-1 inhibitor use was independently associated with higher odds of complete response (OR 7.89; 95% CI 1.70–36.65). In the minority of patients who relapsed after an initial response to IL-1 inhibitors due to treatment discontinuation or tapering, the addition of corticosteroids restored the response. Conclusions: Schnitzler syndrome is a rare autoinflammatory condition predominantly affecting older males, characterized by chronic urticaria, fever, and IgM kappa gammopathy. While IL-1 inhibitors and corticosteroids offer high rates of clinical response, the frequent relapse upon tapering underscores the need for long-term maintenance. Studies are needed to explore if anti-plasma cell therapy would decrease relapse and induce long-term remission.
2026-05-22 | Cutaneous diseases caused by monoclonal immunoglobulin and/or free light chains (monoclonal gammopathy of cutaneous significance).
Monoclonal immunoglobulin (M-Ig) and/or free light chains (FLC) can cause a wide range of organ and tissue damage. The most common are various forms of nephropathies, for which the term monoclonal gammopathy of renal significance was created, and a morphological classification was proposed by the "International Kidney and Monoclonal Gammopathy Research Group." Another large group consists of clinical entities where, among other things, various forms of skin damage occur. For these, the group designation monoclonal gammopathy of cutaneous significance was created. Although the etiopathogenesis is hematologic, the symptoms lead patients with this form of monoclonal gammopathy-related damage to dermatology clinics. Dermatological publications from the last 5 years distinguish diseases with a clearly expressed etiopathogenetic connection to monoclonal gammopathy, defining a total of 12, and then mention other diseases in which the etiopathogenetic relationship is less clear. The group of skin diseases with a clearly demonstrated connection to monoclonal gammopathy includes: AL amyloidosis of the skin, cutaneous macroglobulinemia, skin changes in POEMS syndrome, scleromyxedema, scleroderma, diffuse normolipidemic xanthomas, necrobiotic xanthogranuloma, urticaria in Schnitzler syndrome, telangiectasia in TEMPI syndrome, localized erythema in AESOP syndrome, cryoglobulinemic skin changes, cutis laxa (loose skin). Among the diseases with a less clear connection to monoclonal immunoglobulin, we mention IgA pemphigus. The text provides brief descriptions supplemented with imaging documentation of cases we have encountered over the past 35 years. If a dermatologist encounters the mentioned diseases, they should examine M-Ig and FLC, and in the case of a positive finding, consult with a hematologist regarding the possibility of targeted therapy.
2026-01-22 | [No mistakes with Schnitzler syndrome].
Schnitzler syndrome is a rare autoinflammatory disease that primarily manifests in adulthood. In cases presenting with chronic urticaria and paraproteinemia, Schnitzler syndrome should be considered in the differential diagnosis, and the Strassburg criteria should be applied to establish the diagnosis. IL-1 inhibitors have proven to be an effective long-term treatment for Schnitzler syndrome. Patients should be moni-tored for the potential development of lymphoproliferative disorders and/or amyloidosis.
2025-07-01 | Unexplained fever and rash: a case of Schnitzler syndrome
Abstract Introduction Fever, rash and joint pain are common manifestations of rheumatism. The article reports a patient with recurrent fever and rash, and the final diagnosis of Schnitzler syndrome. The course of diagnosis and treatment was described in detail, and the clinical manifestations, pathogenesis, diagnosis and treatment of the disease were further discussed. Case presentation In this article, we report a 59-year-old man who had recurrent fever, rash, and joint pain for 7 years. Once considered as adult still's disease, anti-neutrophil cytoplasmic antibody-associated vasculitis and systemic inflammatory response syndrome, long term use of hormones and immunosuppressants for treatment, with intermittent attacks, about 15–20 days per occurrence. The interval of rash and fever in the two weeks before admission has shortened, about every 3–5 days. No abnormalities were found in infection, immunity and other related examinations, IgM κ M protein was positive, PET-CT and bone marrow biopsy did not indicate tumor, the patient met the diagnostic criteria for Strasbourg Schnitzler syndrome, and Schnitzler syndrome was finally diagnosed. Result The patient was treated with tocilizumab, a humanized anti-IL-6 receptor antibody, and developed skin allergy. Adjustment for methylprednisolone 8 mg once a day, colchicine 0.5 mg twice a day, tofacitinib 5 mg twice a day, waiting for IL-1 receptor antagonist.
2025-06-10 | Low-level NLRP3 mosaicism in chronic urticarial lesions: extending the phenotypic spectrum of NLRP3-related disorders and therapeutic implications.
Chronic urticarial lesions, a common condition of mostly unknown cause, can occur in immune dysregulation disorders such as hypocomplementaemic urticarial vasculitis syndrome (HUVS), neutrophilic urticarial dermatosis (NUD) and systemic autoinflammatory diseases (SAIDs), including Schnitzler syndrome. To identify the molecular basis of nonpruritic chronic urticarial eruptions in four unrelated patients initially diagnosed with neonatal NUD, Schnitzler syndrome, HUVS or giant-cell arteritis. Conventional next-generation sequencing (NGS) of leucocyte DNA was supplemented with high-depth NGS (> 1500×) to improve the detection of low-level mosaicism in SAID-related genes. Functional assays were performed on recombinant NLRP3 proteins to assess the impact of the identified variations on the nuclear factor-κB (NF-κB) pathway. One patient presented with persistent isolated urticarial lesions since birth, while the other three experienced late-onset skin lesions. In contrast to the initially suspected diagnoses, conventional NGS revealed NLRP3 mosaicism in two patients, with variant allele fractions (VAFs) of 5% and 11%, respectively. In the other two patients, high-depth NGS uncovered NLRP3 mosaicism with VAFs as low as 2-3%. All identified variations activated the NF-κB pathway, demonstrating a gain-of-function effect. Subsequent anti-interleukin-1 therapy led to symptom improvement for all patients. This study highlights the importance of considering NLRP3 mosaicism as an underlying pathological mechanism in chronic urticarial lesions, whether of early or late onset, and whether isolated or mimicking other conditions. As blood contains key target cells for NLRP3 inflammasome activation, even extremely low-level leucocyte mosaicism can be pathogenic. High-depth NGS-based diagnosis of NLRP3-related disorders enables timely initiation of anti-IL-1 therapy, which is crucial to preventing complications such as systemic amyloidosis.
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Drug Discovery Landscape
2 orphan drug designations for Schnitzler syndrome.
2 orphan drug designations for Schnitzler syndrome.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
heterodimeric fusion protein that binds to IL-1 beta consisting of human extracellular domain of IL1 receptor and a mutant Fc fragment of human IgG1 and part of human IL1 receptor accessory protein | proteins | FDA | 2018-10-15 | — | R-Pharm Overseas |
Gevokizumab | antibodies | EMA | 2014-08-22 | — | Xoma UK Limited |
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