Rheumatic involvement and bone scan features in Schnitzler syndrome: initial and follow-up data from a single-center cohort of 25 patients.

OBJECTIVE: To report on the characteristics and long-term course of rheumatic manifestations in Schnitzler syndrome (SchS). METHODS: A retrospective cohort study of patients with SchS followed between 2000 and 2020. Inclusion criteria included a diagnosis of SchS (Strasbourg criteria). All available bone scans were reviewed and scored according to the intensity and number of pathological sites. The scintigraphic score was compared with the clinical activity score, CRP level, and treatments. RESULTS: Twenty-five patients were included. Median age at diagnosis was 68 years. Eighty patients (72%) had SchS-related rheumatic pain. Most patients had a long-standing isolated rash before constitutional and/or rheumatic symptoms appeared. The monoclonal component level was usually very low (IgMκ in 22/25). Rheumatic pain predominated around the knees. Bone scans revealed abnormal tracer uptake in 15/18 (85%). The scintigraphic score correlated with clinical activity (r = 0.4, p < 0.02) and CRP level (r = 0.47, p < 0.01). The scintigraphic score was lower in patients receiving corticosteroids or IL1Ra (interleukin 1 receptor antagonist) than in untreated patients (median scores:2, 0, and 13, respectively; p < 0.05). Two patients developed Waldenström macroglobulinemia. Of the 22 surviving patients, median age at follow-up was 76 years. IL1Ra was used in 13 patients, with dramatic efficacy on both symptoms and bone scan features. CONCLUSIONS: Rheumatic manifestations are very prevalent in SchS. However, bone pain can be misleading and contribute to misdiagnosis. Bone scan abnormalities are very prevalent and correlate with disease activity and treatments. IL1-Ra has a dramatic and durable efficacy but may not be required in every patient early on.

Diagnostic value of 18-F fluorodeoxyglucose PET/CT and bone scan in Schnitzler syndrome.

Introduction: Schnitzler syndrome is an auto-inflammatory disease defined by chronic urticarial eruption and monoclonal gammopathy. 18F fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) is often performed, but its utility in Schnitzler syndrome has not been specifically investigated. The aim of this study was to determine whether PET/CT is informative in the diagnosis and follow-up of Schnitzler syndrome relative to other imaging techniques, including bone scans.Patients and methods: Patients of this study were selected from the French cohort established by Néel et al. All patients with a diagnosis of Schnitzler syndrome (according to Strasbourg's and Lipsker's criteria) who had at least one PET/CT were included. Data were collected from medical records. PET/CT scans were all reviewed by a nuclear physician blinded to the clinical and imaging data.Results: Ten patients underwent at least one PET/CT scan and all had at least one 99mTechnetium bone scan during their follow-up. The most frequent PET/CT abnormalities were diffuse bone-marrow and/or increased femoral fluorodeoxyglucose uptake, but they did not correlate with disease activity. Conversely, bone-scan abnormalities, including mainly increased radiotracer uptake in long bones, appeared to strongly correlate with Schnitzler syndrome activity.Discussion: PET/CT does not appear to be useful for the diagnosis and follow-up of Schnitzler syndrome. However, bone scans appear to be more sensitive for diagnosis and may correlate with clinical activity. Bone scans may be well positioned to distinguish Schnitzler syndrome relapse from other aetiologies of bone, joint, or muscle pain.Conclusion: Bone scans may be favoured over PET/CT in Schnitzler syndrome.

Correlative bone imaging in a case of Schnitzler's syndrome and brief review of the literature.

UNLABELLED: Schnitzler's syndrome is a rare disease characterized by a monoclonal IgM (or IgG) paraprotein, a nonpruritic urticarial skin rash, and 2 (or 3) of the following: recurrent fever, objective signs of abnormal bone remodeling, elevated CRP level or leukocytosis, and a neutrophilic infiltrate on skin biopsy. It responds well to treatment with the interleukine-1-inhibitor anakinra. We report the bone scintigraphy and MRI findings in a 45 years old man with this syndrome and compare them with data from the literature. CONCLUSION: None of the imaging findings are specific, but they lead to a differential diagnosis including infiltrative diseases (e.g. systemic mastocytosis or Erdheim-Chester disease) and dysplastic diseases (e.g. melorheostosis, Camurati-Engelmann disease or van Buchem disease). The bone scintigraphy pattern may be very suggestive of the correct diagnosis and of bone involvement in this syndrome.

Successful use of anakinra to treat refractory Schnitzler's syndrome.

Schnitzler's syndrome is a rather rare disease which may appear in a rheumatologist's office because patients often report rheumatic symptoms with joint, bone and muscle pain. However, it is characterized by chronic urticaria, recurrent fever, liver and spleen enlargement, osteosclerosis, and lymphadenopathy, in conjunction with a serum IgM M component. A patient who had been treated with relatively high doses of corticosteroids for 10 years with insufficient response was treated with the IL-1 receptor antagonist anakinra, this led to a complete resolution of symptoms.

Radiological aid to clinical diagnosis of Schnitzler's syndrome: multimodality imaging approach.

Schnitzler's syndrome is a rare combination of chronic urticaria, fever of unknown origin, disabling bone pain, and monoclonal gammopathy. We report a case with an unusual radiological manifestation as a solitary sclerotic lesion of the right iliac bone. Its main features on conventional radiography, computed tomography, and magnetic resonance imaging are described, and the main radiological differential diagnoses are discussed to help with the characterization of this syndrome, which requires a combination of clinical, laboratory, and radiological data. On the other hand, although our patient had an excellent clinical response to anakinra, the sclerotic lesion remained unchanged on follow-up X-ray examinations.

Schnitzler's syndrome treated successfully with intravenous pulse cyclophosphamide.

Schnitzler's syndrome is a rare clinical condition characterized by chronic urticaria, intermittent fever, bone pain, arthralgia or arthritis, and monoclonal immunoglobulin M (IgM) gammopathy. Here we describe the case of a 48-year-old Italian female with a long history of arthralgia, leucocytosis, spiking fever, and chronic urticaria with severe pruritus. The IgM-kappa monoclonal component in the serum and bone densification on conventional X-ray with hyperfixation on bone technetium scanning at the distal part of the femurs and at the proximal part of the tibias were detected 4 years after the onset of the symptoms. After many ineffective treatments, the use of pulse cyclophosphamide (CPX) resulted in complete remission of the disease that is still lasting after a 2-year follow-up.