Table 1. Characteristics to distinguish chronic spontaneous urticaria from important differential diagnoses.
| Characteristics | Chronic spontaneous urticaria | Urticarial vasculitis | Autoinflammatory diseases | |
|---|---|---|---|---|
| Cryopyrin-associated periodic syndrome | Schnitzler syndrome | |||
| Skin | Wheals and/or swellings | Wheals with/without swellings | Cold-associated appearance of wheals, partly maculopapular exanthema | Wheals |
| Duration of individual efflorescences | Transient, minutes to hours | > 24 hours in most cases | Hours to 24 hours | Hours to 24 hours |
| Localization of efflorescences | Rather asymmetric distribution, whole body | Whole body | Rather symmetrical, face less often affected | Rather symmetrical, often on the trunk of the body |
| Accompanying symptoms on the skin | Strong itching | Rarely itching, burning, pain postinflammatory hyperpigmentation | Burning | Burning |
| Occurrence of angioedema | Possible (~ 40 - 50%) | Occurrence possible | Not described | Very rare |
| Systemic complaints | Rare | Spectrum: joint pain, fever, muscle pain, gastrointestinal, pulmonary, renal involvement | Spectrum: depending on the degree of expression, including fever, fatigue, arthralgia/arthritis, ocular inflammation, headache | Fever, arthralgias, muscle/bone pain, fatigue |
| Age at onset of disease | Any age, in most cases > 30 years of age. | Midlife (~ 45th year of life) | Since birth/early childhood but also possible in later adulthood in milder forms | 50th – 60th year of life |
| Duration of disease | Mean/median: ~ 1 – 4 years | Mean/median: ~ 1 – 4 years | Lifetime | Usually since the onset of the disease, then lifelong |
| Gene/ mode of inheritance | – | – | NLRP3 autosomal dominant or sporadic |
Complex |
| Possible consequences and complications | Severe impairment of quality of life | Severe impairment of quality of life, involvement of internal organs for example lungs, kidney | Severe impairment of quality of life, amyloidosis, sensorineural deafness, central nervous system involvement | Severe impairment of quality of life, lymphoproliferative disease, amyloidosis |
| Inflammatory markers | CRP may be slightly elevated, usually unremarkable | CRP, ESR elevated; In hypocomplementemic form: C3, C4 decreased, C1q antibodies |
CRP, ESR, SAA, S100A8/9 elevated; leukocytosis with neutrophilia | CRP, ESR, SAA, S100A8/9 increased, leukocytosis with neutrophilia |
| Histology of the lesional skin | Dermal edema and sparse mixed-cell perivascular infiltrate | Leukocytoclastic vasculitis | Perivascular and interstitial neutrophil-rich infiltrate | Perivascular and interstitial neutrophil-rich infiltrate |
| Efficacy of antihistamines | Yes | Rare | No | No |
| Efficacy of omalizumab | Yes; approval | Case reports and series described | No | No |
| Efficacy of Interleukin-1 blockade |
No | Case series described | Yes; approval for anakinra and canakinumab | No approval; interleukin-1 blockade effective |
| Characteristic features | Therapeutic response to H1 antihistamines or omalizumab | Healing of wheals with postinflammatory hyperpigmentation, histology with leukocytoclastic vasculitis. | Cold-related complaints | Monoclonal gammopathy |
CRP = C-reactive protein; ESR = erythrocyte sedimentation rate; IL = interleukin; SAA = serum amyloid A.