Eosinophilic cellulitis: causes, symptoms, diagnosis, treatment, and prognosis

Eosinophilic cellulitis, as known as Wells syndrome, or recurrent granulomatous dermatitis with eosinophils, is a disease characterized by clinically acute cellulitis and massive eosinophil infiltration, tissue edema, and flame figures in histopathology, more common in adults, but also in children, even in newborns. There are no significant gender and ethnic differences in the incidence.


Causes

The etiology of this disease is still unknown, but some patients have a history of insect bites, surgery, fungal infections, parasitic diseases, and medications such as penicillin prior to the disease, suggesting that the disease is a hypersensitivity reaction triggered by various factors. In addition, the eosinophils in the peripheral blood of patients are often increased, atopic disease is often present, fibrinoid necrosis can be seen in histopathology, direct immunofluorescence can reveal immunoglobulin and complement deposition around the cutaneous blood vessels, and antinuclear antibody test can be positive, suggesting that the disease is an autoimmune or allergic disease. Significantly increased platelets and leukocytes in very few patients suggest that the disease may be associated with myeloproliferative diseases. It is also believed that this disease is a benign form of eosinophilic disease in few patients.


Signs and Symptoms

The disease occurs predominantly in females, mainly in adults, occasionally in children, and often invades mainly the trunk and extremities and occasionally the face.

Acute, localized, sharply demarcated, cutaneous and subcutaneous, infiltrative, edematous, brownish erythema suddenly occur, rapidly expanding within 1 - 3 days, and the center of the erythema subsides. The subjective symptoms are pruritus, distending pain, and burning sensation, and tenderness may be present. Bullae may occur in the skin lesions in severe patients. The initial lesions may be non-specific, and can be similar to urticaria, angioedema, and contact dermatitis, but then the skin lesions are very similar to acute bacterial cellulitis, but the local temperature is not rising, and there is no response to antibiotic treatment. In mild patients, skin lesions are sometimes similar to erythema annulare and erythema elevatum diutinum.

1 - 3 weeks after onset, the acute redness and inflammation subside, and skin lesions gradually develop into painless, hard, cutaneous or subcutaneous, infiltrative plaques or nodules. Skin lesions are bluish gray, with rosy or purple edges. Subsequently, the skin lesions can be pale or atrophic, sometimes similar to circumscribed morphea. The skin lesions completely regress without leaving scars. However, alopecia atrophicans can occur if the scalp is involved. Systemic symptoms are usually absent, some patients have fever during severe attacks, and some patients may develop asthma and arthralgia. The disease can relapse, often persisting for more than few months, up to decades, eventually in spontaneous remission.


Histopathology

Typical histopathological changes include three phases.

In the acute phase, dermal edema, occasionally subepidermal vesicles, dermal eosinophil, lymphocyte, and histiocyte infiltration, and perivascular inflammatory cell infiltration can be seen.

In the subacute phase, dermal diffuse histiocyte and eosinophil infiltration are visible, and eosinophils and numerous eosinophilic granules adhere to the collagen bundle or around the collagen bundle, forming plaquelike infiltration, termed flame figures.

In the regressive phase, there may still be some eosinophils, flame figures are still present and surrounded by palisaded foreign giant cells and histiocytes, but manifestations of vasculitis are absent.

Flame figures are characteristic manifestations of this disease, but not specific to this disease, because can be seen in bullous pemphigoid, pemphigoid gestationis, tinea pedis, spider and other insect bite reactions, and other inflammatory diseases with eosinophilia.

Most of direct immunofluorescence tests are negative, and non-specific fibrin deposition in the dermis and C3 deposition in the dermal vessels may be seen. IgM, IgA, and C3 deposition in the intramuscular vascular wall and IgM deposition at the junction between epidermis and dermis and on the dermal vascular wall may be present.


Diagnosis

On the basis of clinical manifestations, flame figures in histopathology, and eosinophilia in peripheral blood, the disease can be diagnosed.


Treatment

At present, there is no satisfactory treatment for this disease, and treatment with antihistamines and antibiotics is ineffective. The glucocorticoids temporarily inhibit skin lesions and shorten the duration of the disease. The initial dose of prednisone (or prednisolone) is 20 - 80 mg/d. After the symptoms are controlled, the dose can be gradually reduced until discontinuation, but there may be recurrence after discontinuation. Topical fluocinonide cream and betamethasone valerate cream are also effective in some patients. The mechanism of glucocorticoids treating this disease may be inhibition of eosinophils in blood and inhibition of eosinophil chemotaxis.


Prognosis

The disease is chronic, and can be spontaneously in remission after multiple episodes, so the prognosis is good.