ACUTE FEBRILE NEUTROPHILIC DERMATOSIS

Introduction

Acute febrile neutrophilic dermatosis, is a reactive process characterized by the sudden onset of tender, red-to-purple papules, and nodules that coalesce to form plaques over the skin. These plaques usually occur in the upper extremities, face or neck, often accompanied by fever and peripheral neutrophilia (increase in white blood cells count).

It was first described in 1964 by Robert Sweet; it can range from Classic Sweet disease which commonly occurs in young women after a mild respiratory illness to a more aggressive neutrophilic process, which may be associated with other inflammatory disease or malignant tumors. In fact, the lesions can be the first evidence of an underlying condition and should prompt further investigation.  It can also occur due to some medications.

The diagnosis of Sweet's syndrome is based on clinical and histopathological studies. The characteristics that distinguish the Sweet syndrome lesions from other neutrophilic dermatoses are wound healing without scarring and the absence of vasculitis.

Alternative Name

Sweet's syndrome

Pathophysiology

Acute febrile neutrophilic dermatosis (Sweet's syndrome) is an hypersensitivity reaction, in response to systemic factors such as hematologic disorders, infections, inflammation, immunization or through the action of drugs. The condition is characterized by excess of neutrophils (white blood cells) in blood.

Epidemiology

Acute febrile neutrophilic dermatosis (Sweet's syndrome) is rare but not unusual. Most are idiopathic or associated with benign diseases. It is commonly seen in women between 30-50 years. Sweet's syndrome in children is very rare and usually associated with infection. Female-male ratio is of 15:1.

Most cases of Sweet's syndrome resolve, although some may persist indefinitely and can be difficult to manage because of the pain and skin lesions. Since this condition may be associated with many other diseases, including malignant tumors, the overall prognosis of the patient depends on the underlying cause.

Symptoms & Signs

The fever usually precedes the beginning of each crop of lesions. Fever may precede the skin disease for several days or weeks, or it may occur simultaneously. The crop of plaques or nodules in the classic form often appears abruptly and may persist for weeks or several months (days to weeks) if left untreated.

Many patients report a febrile upper respiratory tract infection, tonsillitis or flu-like 1-3 weeks before the onset of skin lesions. Vaccination or an infection of the gastrointestinal tract may also precede the eruption. Headache, malaise and joint pain are common.

Cutaneous manifestations of acute febrile neutrophilic dermatosis (Sweet's syndrome):

Typical skin lesions are papules blue or purple-red plaques or nodules. The lesions may be studded with pustules. Plaques can cause pain and burning, but they are not pruritic (itching). Lesions spontaneously resolve without scarring, or they resolve after treatment. The face, neck, and extremities primarily are affected, characteristically in an asymmetric distribution.

Bullae and ulcers are more common with malignant tumors. These injuries can be extensive and are usually difficult to treat.

Treatment Options

Prednisolone (corticosteroid is the drug of choice). Pulmonary infiltrates tend to respond quickly. But despite the excellent initial reactions recurrence is common.

Long-term management can be achieved by a variety of drugs but none has proven to be better than corticosteroids. They include indomethacin, colchicine, dapsone, and cyclosporine. They have also used etretinate, clofazimine and pentoxifylline.

If an underlying cause can be identified it should be treated, for example, by resection of solid tumors, treating infections, and discontinuation of causative medication. Successful treatment of underlying illness may promote resolution of Sweet's syndrome and prevent relapses.

Refrences & Links

• www.emedicine.com 
  

Tests & Diagnosis
The diagnosis of acute febrile neutrophilic dermatosis (Sweet syndrome) is usually based on histopathologic examination by a qualified dermatopathologist, as the lab findings are commonly nonspecific. 

Blood test

• A complete blood count - Neutrophilia is often present
• Anemia and thrombocytopenia in patients with underlying malignancy is usual occurrence 
• Blood count abnormalities should prompt investigation of bone marrow biopsy. 
• (ESR) and CRP levels are elevated

• A urinalysis may show proteinuria and / or hematuria. 
• Lesions can be cultured for bacteria, fungi, and mycobacteria to rule out infection.
• A chest radiograph should be obtained if the pulmonary symptoms are present
• Sweet's syndrome is the presenting sign of cancer in about two thirds of cases of cancer associated with Sweet syndrome. The presence of ulcerative lesions, oral lesions, abnormal platelet count or anemia should prompt the investigation of an underlying disease.
• 2 - [fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) is particularly useful in the assessment of myeloproliferative disorders, but also for the assessment of solid tumors, useful and successful represented the beginning of malignant tumors.

• The skin should be biopsied to confirm the diagnosis of acute febrile neutrophilic dermatosis (Sweet's syndrome).
• Bone marrow aspiration is indicated if the CBC is abnormal and should be considered in all cases of Sweet's syndrome with atypical bullous or ulcerative Sweet syndrome.
• Age appropriate cancer screening and assessment for inflammatory bowel disease to be carried out, if no other cause is found, particularly in patients with ulcerative lesions or bullous.