What is eosinophilic cellulitis?
Eosinophilic cellulitis is an uncommon recurrent inflammatory skin disease, also known as Wells syndrome.
Eosinophilic cellulitis
Who gets eosinophilic cellulitis?
Eosinophilic cellulitis can affect all age groups including children and infants.
What causes eosinophilic cellulitis?
The cause of eosinophilic cellulitis is unknown. It is believed to be a local hypersensitivity reaction.
Most cases appear to be idiopathic. Implicated triggers or associations include:
- Infection
- Arthropod bite
- Medications and immunisations
- Haematological disorders and malignancies.
What are the clinical features of eosinophilic cellulitis?
Eosinophilic cellulitis usually presents as itchy or burning erythematous nodules or plaques resembling cellulitis or erysipelas on a limb. However, the clinical appearance is variable: lesions can be single or multiple, the face and trunk may be affected, and clinical morphology can include:
- Plaque type
- Annular granuloma-like
- Urticaria-like
- Papulovesicular
- Bullous
- Papulonodular
- Fixed drug eruption-like.
The classic plaque-type variant of eosinophilic cellulitis is the most common presentation in children, whereas the annular granuloma-like variant is more frequently seen in adults.
Individual lesions can resolve spontaneously but typically recur.
Associated systemic symptoms may include fever and arthralgias.
What are the complications of eosinophilic cellulitis?
Eosinophilic cellulitis may be rarely complicated by superinfection.
Severe swelling of a limb can cause compartment syndrome.
How is eosinophilic cellulitis diagnosed?
Eosinophilic cellulitis is often misdiagnosed initially as cellulitis or erysipelas, and is only considered when antibiotic treatment is unhelpful.
Proposed diagnostic criteria for eosinophilic cellulitis require at least two major and one minor criteria.
Major criteria
Major criteria for an eosinophilic cellulitis diagnosis include:
- Clinical picture to include any of the reported variants
- No evidence of systemic disease
- Relapsing, remitting course
- Histology comprises eosinophilic infiltrates without vasculitis.
Minor criteria
Minor criteria for an eosinophilic cellulitis diagnosis include:
- Peripheral eosinophilia not persistent and not greater than >1.5 x 109/L
- Histology has granulomatous change
- Flame figures
- A triggering factor (eg, a drug).
Peripheral eosinophilia affects approximately 50% of cases but is not required for diagnosis.
Skin biopsy is usually required and the histological findings depend on the stage of disease.
- Key findings in the acute phase are dermal oedema with an eosinophilic infiltrate and without vasculitis.
- The subacute phase shows the characteristic ‘flame figures’.
- The chronic phase is granulomatous with histiocytes and giant cells (see Wells syndrome pathology).
Flame figures are not pathognomonic of Wells syndrome and can be seen with other eosinophilic infiltrates, such as:
- Bullous pemphigoid
- Arthropod bite reactions
- Eosinophilic granulomatosis with polyangiitis
- Parasitic infection.
What is the differential diagnosis for eosinophilic cellulitis?
The differential diagnosis for eosinophilic cellulitis may include:
- Bacterial cellulitis and erysipelas
- Parasitic infestation
- Eosinophilic granulomatosis with polyangiitis
- Arthropod bite.
What is the treatment for eosinophilic cellulitis?
Eosinophilic cellulitis rapidly responds to an oral corticosteroid, such as prednis(ol)one, but often relapses when the steroid dose is reduced.
Other treatments used may include:
Treatment of an associated trigger, such as cessation of an implicated drug, can lead to complete resolution.
What is the outcome for eosinophilic cellulitis?
Eosinophilic cellulitis has a benign course with a tendency for lesions to spontaneously resolve. However, recurrence is common.