Skin nontumor
Dermal non-granulomatous granulocyte-rich reaction patterns
Wells syndrome

Topic Completed: 1 July 2017

Minor changes: 10 November 2020

Copyright: 2002-2020,, Inc.

PubMed Search: Wells Syndrome [title]

Favia Dubyk, M.S. M.D.
Hillary Rose Elwood, M.D.
Page views in 2019: 3,007
Page views in 2020 to date: 2,732
Cite this page: Dubyk F, Elwood HR. Wells syndrome. website. Accessed November 26th, 2020.
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 to 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 are 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 answer #1
    C. Often clinically resembles cellulitis, hence it's other name "eosinophilic cellulitis".

    1. False: 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.
    2. False: older lesions can have a granulomatous component, sometimes with prominent giant cells.
    1. False: seen in up to 67% of patients but not required for diagnosis.
    2. False: vasculitis typically absent although there may be extravasated erythrocytes.

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