Conference Coverage

Neutrophilic urticarial dermatosis is usually misdiagnosed



– Neutrophilic urticarial dermatosis (NUD) in patients with systemic lupus erythematosus (SLE) is “almost always” initially misdiagnosed as a lupus flare and treated inappropriately, Dan Lipsker, MD, PhD, said in a plenary address at the annual congress of the European Academy of Dermatology and Venereology.

“This is a condition that is underdiagnosed and overtreated,” declared Dr. Lipsker, professor of dermatology at the University of Strasbourg (France).

Dr. Dan Lipsker of the University of Strasburg, France Bruce Jancin/Frontline Medical News

Dr. Dan Lipsker

He should know. He was senior author of a 2009 paper that defined and named the disorder (Medicine. 2009 Jan;88[1]:23-31).

NUD is not rare. Dr. Lipsker estimates it occurs in 1%-2% of patients with SLE. In a retrospective study of seven patients with NUD and SLE, he and his colleagues reported that NUD was initially misdiagnosed as a lupus flare in 4 patients, who were then treated with immunosuppressive drugs (Medicine. 2014 Dec;93[29]:e351]). “That’s quite logical because the patients had a rash, fever, and joint pain,” the dermatologist noted.

However, misdiagnosis of NUD leads to a ramping up of immunosuppressive therapy directed at the patient’s SLE, which is counterproductive: It won’t alleviate the symptoms and needlessly exposes the patient to drug toxicities.

The treatment for NUD is not prednisone, mycophenolate mofetil, an antimalarial, or other drugs conventionally prescribed for SLE; it’s a drug that inhibits neutrophil migration, such as dapsone at 50-200 mg per day or colchicine at 0.5-1.0 mg per day. Typically, within just a few days after starting the appropriate therapy, the joint pain and rash of NUD are gone, according to Dr. Lipsker.

Making the diagnosis

The rash of NUD is distinctly different from a classic lupus rash. It consists of pale red macules or slightly raised nonpruritic papules. Individual lesions will disappear spontaneously within 24-48 hours.

The histopathology of NUD is characteristic of a neutrophilic dermatosis. On biopsy, an intense neutrophilic perivascular and interstitial infiltrate with leukocytoclasia is seen. There is no damage to the blood vessel walls, which readily distinguishes NUD from urticarial vasculitis.

Other neutrophilic dermatoses have also been reported with increased frequency in patients with SLE. These include Sweet syndrome, pyoderma gangrenosum, bullous SLE, amicrobial pustulosis of the folds, and palisaded neutrophilic granulomatous dermatitis. Dr. Lipsker lumps them, together with NUD, as neutrophilic cutaneous lupus erythematosus. Affected SLE patients have an exaggerated innate immune response. It is as yet unclear if these neutrophilic dermatoses have prognostic significance in the setting of SLE, he said.

Dr. Lipsker reported having no financial conflicts of interest regarding his presentation.

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