Recurrent Pruritic Multifocal Erythematous Rash

The Diagnosis: Wells Syndrome 

Histopathologic examination of the biopsy demonstrated overlying acanthosis, focal spongiosis, and exocytosis. There also was proliferation and thickening of superficial capillaries and papillary fibrosis (Figure, A). There was a mixed interstitial and perivascular inflammatory infiltrate consisting of lymphocytes, histiocytes, plasma cells, and eosinophils (Figure, A and B). Occasional flame figures were identified (Figure, C). 

Wells syndrome, also known as eosinophilic cellulitis, was first described in 1971 by Wells¹ as a recurrent granulomatous dermatitis with eosinophilia. Rarely reported worldwide, this chronic relapsing condition is characterized by a pronounced eosinophilic infiltrate of the dermis resembling urticaria or cellulitis.² The exact etiology has not been elucidated; however, links to certain medications, vaccines, exaggerated arthropod reactions, infections, and malignancies have been documented.³  

Wells syndrome is a diagnosis of exclusion and lacks a predictable dermatologic presentation, thereby mandating focused clinical follow-up as well as correlation with histopathology findings. Although the classic histologic hallmark of Wells syndrome is scattered flame figures, this finding is not specific and can be found in other hypereosinophilic conditions.² Clinical manifestations most often consist of 2 distinct phases: an initial painful burning or pruritic sensation, followed by the development of erythematous and edematous dermal plaques that may heal with slight hyperpigmentation over 4 to 8 weeks. A case series of 19 patients demonstrated variants of Wells syndrome, with an annular granuloma-like appearance found primarily in adults and the signature plaque-type appearance predominating in children.⁴  

Acute urticaria is characterized by pruritic erythematous wheals secondary to a histamine-mediated response brought on by a variety of triggers, typically allergic and self-resolving within 24 hours. When such lesions last longer than 24 hours, biopsy should be performed to exclude urticarial vasculitis, which is characterized by a burning or painful sensation rather than pruritis, in addition to dermal neutrophilia and perivascular infiltrate on histology. Erythema migrans of Lyme disease begins at the site of a tick bite, evolving from a red macule to an expanding targetoid lesion and typically is not pruritic. Infectious cellulitis presents with warm, tender, and poorly defined erythematous patches; can progress rapidly; and is accompanied by systemic symptoms such as fevers, malaise, and lymphadenopathy.  

Best evidence favors the use of moderate- to high-dose corticosteroids as first-line treatment.⁵ The use of tumor necrosis factor blockers, various immunomodulating agents, and combination therapy with levocetirizine and hydroxyzine have demonstrated variable levels of efficacy, albeit often followed by high rates of relapse with drug discontinuation.⁶