A Brehon, P Moguelet, V Seta, E Amsler, A Fajac, A Barbaud, A Soria, JB Monfort
J Eur Acad Dermatol Venereol . 2021 Nov 6. doi: 10.1111/jdv.17788. Online ahead of print.
There are some arguments on whether neutrophilic urticaria (NU) is distinct from chronic spontaneous urticaria (CSU), although with no consensus. This study aimed to compare clinical, biological, and histological characteristics and therapeutic responses between NU and CSU.
This was an observational, retrospective study that included adults with chronic urticarial rash who had undergone a skin biopsy. One dermatologist and one cytopathologist blindly and independently reviewed the biopsies [cytology counting technique for a precise proportion of neutrophilic/eosinophilic polynuclear cells (PNN/PNEo)]. NU was defined by an inflammatory dermal infiltrate composed of at least 60% PNN, without leukocytoclasia/vasculitis.
Forty-four patients were included, and their biopsies were classified into two groups: NU (n=28) and CSU (n=16). From the bibliography, there are no characteristics related to PNN at histology, but an increase in erythrocyte sedimentation rate in the NU group (p=0.03). Colchicine also showed to be more effective in cases of significant neutrophilic infiltrate: 42.85% effectiveness in NU group versus 6.25% in CSU group.
Two other findings were a statistically associated relation with neutrophilic venulitis (p=0.04) (corresponding to an intraparietal aggregation of PNN without vasculitis) and a basophilic interstitial flame figure corresponding to degranulation of the PNN cytoplasm and exclusively associated with NU (p=0.04).
A diagnostic score was established using strict quantitative histological criteria (intensity of neutrophilic infiltrate, the existence of neutrophilic venulitis, basophilic flame figures, and intense leukocytoclasia), which allows the classification of urticarial eruptions into NU or UCS.
This score will allow diagnosis and homogenization of NU patients (it correctly classified 40 of the 44 patients from the study).
In conclusion, NU is an independent entity as some histological images were significantly (neutrophilic venulitis) or exclusively (basophilic flame figure) associated with an intense neutrophilic infiltrate. A prospective study is needed to validate this new score.