Skin nontumor

Dermal non-granulomatous granulocyte-rich reaction patterns

Wells syndrome

Last author update: 1 July 2017
Last staff update: 14 July 2023

Copyright: 2002-2023,, Inc.

PubMed Search: Wells Syndrome [title]

Favia Dubyk, M.D., M.S.
Hillary Rose Elwood, M.D.
Page views in 2022: 3,618
Page views in 2023 to date: 3,468
Cite this page: Dubyk F, Elwood HR. Wells syndrome. website. Accessed September 21st, 2023.
Definition / general
  • Idiopathic inflammatory dermatitis with eosinophilic infiltration
  • Also known as eosinophilic cellulitis
Essential features
  • Idiopathic condition typically characterized by recurrent pruritic to painful plaques that often clinically resemble cellulitis
  • Histopathology characterized by a prominent eosinophilic infiltrate with "flame figures"
  • Equal prevalence in men and women
  • Most cases sporadic
  • Higher prevalence in adults than children
  • Unknown
  • Some cases may be secondary to hypersensitivity reaction┬áto insect bites, medications, infections, vaccinations, malignant tumors or myeloproliferative disorders (J Clin Aesthet Dermatol 2011;4:55)
Clinical features
  • Clinical picture is variable but most often recurrent bouts of edematous nodules and plaques, often preceded by prodromal itching or pain
  • Usually a limited course over weeks to month but often recur
  • May resemble cellulitis clinically but not warm or tender (Postepy Dermatol Alergol 2014;31:322) and does not improve with antibiotics (J Clin Aesthet Dermatol 2011;4:55)
  • Erythematous papules, plaques or nodules that may be painful or pruritic (Postepy Dermatol Alergol 2014;31:322)
  • Sometimes annular configuration, can blister
  • May be single or multiple
  • Peripheral blood eosinophilia common (found in 67% of cases) (Can J Plast Surg 2012;20:91)
  • Leukocytosis (found in 41% of cases)
  • Oral or topical corticosteroids most commonly, often with dramatic improvement
  • Antihistamines and immunomodulatory agents also used for refractory or unresponsive cases
Clinical images

Images hosted on other servers:

Swollen plaques on right forearm

Diffuse erythematous plaque

Resembling bacterial cellulitis

Microscopic (histologic) description
  • Diffuse dermal infiltrate of perivascular and interstitial eosinophils throughout superficial and deep dermis, often with extension into subcutis
  • Admixed histiocytes and lymphocytes
  • Old lesions may show granulomas
  • Flame figures often present (deposition of eosinophil basic protein on collagen bundles)
  • Can have subepidermal edema, sometimes with blister formation
  • May have eosinophilic spongiosis
  • No vasculitis
Microscopic (histologic) images

Contributed by Favia Dubyk, M.S., M.D.

Nodular collections of eosinophils

Images hosted on other servers:

Diffuse dermal eosinophilic infiltrate

High power view of eosinophils and flame figures

Multiple flame figures

Interstitial infiltrate
with eosinophils
magnification 100x

Numerous eosinophils magnification 200x

Differential diagnosis
  • Bacterial cellulitis: dermal to subcutaneous infiltrate of neutrophils, often with superficial dermal edema; typically lacks flame figures and neutrophils predominate over eosinophils
  • Churg-Strauss syndrome: may have similar eosinophilic granulomas, vasculitis not always present in skin biopsy, clinical correlation helpful
  • Eosinophilic annular erythema: has features of Wells syndrome as well as dermal mucin, vacuolar interface change
  • Flame figures are rarely seen in allergic contact dermatitis, arthropod bite reaction, bullous pemphigoid, dermatophyte infection, drug reaction, herpes gestationis; correlation with clinical findings is needed
  • Parasite infestation: can appear identical to Wells syndrome; in areas with endemic parasite infections, lesions resembling Wells syndrome are more often related to an underlying parasite infection
  • Board review style question #1
    Which of the following statements is true of Wells syndrome?

    1. Flame figures are pathognomonic
    2. Granulomatous inflammation always absent
    3. Lesions can clinically resemble cellulitis
    4. Peripheral blood eosinophilia is required for diagnosis
    5. Vasculitis usually present
    Board review style answer #1
    C. Often clinically resembles cellulitis, hence it's other name eosinophilic cellulitis. Answer A is incorrect because while flame figures are a hallmark of the disease, these can sometimes be seen in a number of other settings such parasite infestation, arthropod bite, drug reaction, allergic contact dermatitis and bullous pemphigoid. Answer B is incorrect because older lesions can have a granulomatous component, sometimes with prominent giant cells. Answer D is incorrect because this is seen in up to 67% of patients but not required for diagnosis. Answer E is inocrrect because vasculitis is typically absent although there may be extravasated erythrocytes.

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