Rare acquired autoinflammatory disorder characterised by chronic urticarial rash with monoclonal IgM gammopathy and systemic inflammation. First described in 1972 by Liliane Schnitzler, the syndrome involves dysregulated IL-1β signalling driving fever, bone pain, arthralgia, and elevated inflammatory markers.
8 key symptoms and signs
| Feature | Frequency | Category | Sources |
|---|---|---|---|
Chronic urticarial rash Non-pruritic or mildly pruritic wheals, often worse in evening. Individual lesions last <24 hours. Neutrophilic dermal infiltrate on biopsy. | 100% | dermatologic | |
Monoclonal IgM gammopathy Obligate diagnostic criterion. IgM-kappa in ~94% of cases. M-spike often low (median 0.6 g/dL). SPEP alone may miss it in 51% — immunofixation required. | 100% | laboratory | |
Recurrent fever Intermittent fever >38°C, often in evening. Resolves within hours of anakinra. | 85% | systemic | |
Bone pain Predominantly distal femora and proximal tibiae ('hot knees'). Osteosclerotic lesions on imaging in 64%. | 70% | musculoskeletal | |
Arthralgia Joint pain without destructive arthropathy. Large joints most commonly affected. | 75% | musculoskeletal | |
Fatigue Often severe and debilitating. Correlates with inflammatory marker levels. | 80% | systemic | |
Elevated CRP Consistently elevated C-reactive protein reflecting systemic inflammation. Normalizes rapidly with IL-1 blockade. | 95% | laboratory | |
Elevated ESR Erythrocyte sedimentation rate >20 mm/h. Minor criterion in Lipsker criteria. | 90% | laboratory |
Competing explanations ranked by evidence weight