The spectrum of eosinophilic cellulitis (Wells' syndrome): new insights based on 114 cases.

Abstract

Eosinophilic cellulitis (EC), also known as Wells' syndrome, is a rare, poorly studied inflammatory dermatosis. To describe the clinical and histopathological spectrum, associated conditions, outcomes of EC, and treatment response rates. Retrospective multicenter study including patients with biopsy-proven EC. Risk factors for unfavorable clinical course (defined as recurrence or persistent disease >6 months) were assessed using univariable and multivariable logistic regression models. A total of 114 patients (53% female, median age 52 years) were included. The most frequent clinical presentation was papulonodular (52%), with lesions predominantly on the legs (69%). Disabling pruritus was common (83%), whereas systemic symptoms were rare. Histological findings did not differ between patients with or without triggering factors or associated diseases, or between those with or without blood eosinophilia. Triggering factors and associated conditions were identified in 30 (26%) and 24 (21%) patients, respectively. Arthropod bites or stings were the most common triggering factor, whereas hematological malignancies, ANCA-negative eosinophilic granulomatosis with polyangiitis, and idiopathic hypereosinophilic syndrome were the most frequent associated conditions. Most frequently used treatments were topical (54%) and oral corticosteroids (35%), with complete response rates of 67% and 82%. Conventional synthetic DMARDs showed moderate efficacy (complete response ≤31%), whereas biologics targeting type 2 inflammation yielded promising results. In multivariable analysis, lesion size >5 cm was the only variable independently associated with unfavorable clinical course (OR 3.79 [1.42-10.10], p=0.008). EC likely represents a disease spectrum encompassing conditions leading to eosinophil-mediated dermal toxicity. Lesion size >5 cm is associated with unfavorable clinical course. While corticosteroids achieve high remission rates, biologics targeting type 2 inflammation appear promising second-line options warranting further evaluation.