Multiple triggers can produce erosive pustular dermatosis

Erosive pustular dermatosis of the scalp can be mistaken for other conditions like superficial squamous cell carcinoma, actinic keratosis, or a bacterial or fungal infection, according to the Director of Garden City Dermatology, Garden City, New York.

"Many times it gets missed and gets treatment that is ineffective," said Ted Daly M.D., F.A.A.D.,F.S.P.D.,F.A.S.D., in an interview with Dermatology Times. "The most common differential diagnosis is squamous cell carcinoma. It is a clinical diagnosis made after ruling out other conditions."

Erosive pustular dermatosis of the scalp presents as erosions, crusting, and scabbing of the scalp, with pustules, and it usually occurs in sun-damaged skin, explained Dr. Daly, who is board certified in dermatology, pediatric  dermatology, and dermatopathology.

"It is more common in individuals of skin type I or II, but individuals of all skin types can develop it," Dr. Daly says.

Elderly patients, usually in their 70's, are the typical patients who present with erosive pustular dermatosis, and females present with erosive pustular dermatosis in a two-to-one ratio compared to males, Dr. Daly says.

In addition, the condition is one that is chronic and for many patients, it's a long-standing disease, Dr. Daly says.

Many patients develop a scarring alopecia as well, but Dr. Daly has very recently shown regrowth of hair after using topical tacrolimus in a recent publication. Journal ofthe American Academy of Dermatology. 2011 Sep;65(3):e93-4.

"It is always reported as rare, but I think it's not so rare," Dr. Daly says. "We see it frequently because we search for it. I think it's under-diagnosed in the U.S. I believe there is a failure to diagnose it which results in much more surgery being done."

Skin grafts can be performed because clinicians conclude incorrectly there is a non-healing wound or in other instances surgery is performed to remove what is incorrectly suspected of being a squamous cell carcinoma, Dr. Daly explains.

Antibiotic therapy has been prescribed to treat it, and it is unsuccessful in treating it, Dr. Daly notes.

Multiple triggers, besides actinic damage, can produce erosive pustular dermatosis including surgery, the use of photo-dynamic therapy (PDT), cryosurgery, and the use of topical agents to treat actinic damage like 5-fluoruacil, according to Dr. Daly. "It can result from any injury to the area," he said.

One reported case linked the use of imiquimod to the development of erosive pustular dermatosis. Case Reports inDermatological Medicine. 2012;2012:828749

The condition is somewhat of a misnomer, for erosive pustular dermatosis can appear not only on the scalp but in surgically-injured areas, said Dr. Daly, noting it has been observed on the leg and the periumbilical area after surgery.

"Erosive pustular dermatosis is the preferred terminology," Dr. Daly notes.

The etiology of the condition remains unidentified, but there is some speculation of how it arises, Dr. Daly says.

"It is unknown what causes it," Dr. Daly says. "It is speculated that there is faulty wound healing going on. In other words, you have damaged skin to begin with, and it tries to heal, but pustules and crust forms. Most patients who have it look almost identical.

"Some think it has to do with immune dysfunction and the function of neutrophils while others consider it related to poor wound healing and fibroblast damage," he says. "Those are two speculative causes of it. Evidence-based studies  are lacking."

The gold standard for treating erosive pustular dermatosis is topical steroids and the topical calcineurin inhibitor tacrolimus, Dr. Daly says. The disadvantage with using topical steroids is that they may exacerbate existing skin atrophy, Dr. Daly says.

"These patients often end up with hair loss because the condition is inflaming their scalp," Dr. Daly says.

Other therapies that have been used include topical dapsone, which would address neutrophil dysfunction, Dr. Daly says. Other second-line treatments include calcipitriol, zinc sulfate, PDT, oral steroids, acetretin and isotretinoin, but a therapy like isotretinoin will require closer follow-up of patients such as blood monitoring, Dr. Daly says.

Therapies can produce substantial improvement, but patients often experience recurrence, Dr. Daly says.

"Patients usually end up needing to continue with intermittent treatment," Dr. Daly says.

Dr. Daly had no relevant disclosures.