https://orcid.org/0000-0003-3982-3744
An 81-year-old woman presented with a 1-year history of erosions and pustules on her scalp. A red crust first appeared on the scalp after a trauma 1 year ago and gradually spread throughout the scalp. Her family history was unremarkable. Considering the possible existence of infection, she was initially treated with topical antibiotics but had no improvement. Skin biopsy showed impetiginized scale-crust, epidermal atrophy, dermal fibrosis, and perifollicular mixed inflammatory infiltrate, including neutrophils, plasma cells, and lymphocytes, with partial destruction of the hair follicle. To exclude uncommon pathogenic agents, corresponding stains and bacterial and fungal cultures were applied. Physical examination revealed diffuse, thickened, yellow–green crusts on the scalp and scarring alopecia (Figure 1).
Erosions and pustules of the scalp, covered by keratotic crusts.
What is your diagnosis?
Diagnosis: Erosive pustular dermatosis of the scalp
Acid-fast stain, Periodic Acid-Schiff stain, gomori-methenamine silver stain, and bacterial and fungal cultures were negative. A diagnosis of erosive pustular dermatosis of the scalp (EPDS) was made. The patient was treated with topical steroids and calcineurin inhibitors for 5 months with significant improvement (Figure 2).
The appearance of the scalp improved significantly after use of topical steroids and calcineurin inhibitors.
Pye first described the cases of erosive pustular dermatosis in 1979 [1]. It is a rare but sterile inflammatory dermatosis that is characterized by erosions, pustules, ulcerations, and crusts on the scalp and usually affects elderly women. The lesion is often on the scalp; the legs and face can also be involved [2, 3]. The clinical presentation may imitate infectious skin diseases, leading to misdiagnosis. Because diagnostic mistakes and empirical usage of antibiotics may worsen the condition, early diagnosis of EPDS is important.
The causes of EPDS are poorly understood, but local trauma, surgery, burns, and topical medications such as imiquimod can trigger the disease. It has been suggested that the autoimmune reaction induced by trauma results in a secondary inflammatory reaction [4], likely the cause in our case. EPDS has been reported in patients with concurrent autoimmune diseases such as Hashimoto's thyroiditis, Takayasu's arteritis, autoimmune hepatitis, myasthenia gravis, and rheumatoid arthritis [5].
Since the first report of EPDS in 1979, the number of relevant cases and studies has increased gradually, implying that EPDS is likely to be more common than previously imagined [4]. The diagnosis of EPDS mainly depends on clinical manifestations because of negative microbial investigations and aspecific histopathologic features. Ineffective antimicrobial therapy and highly effective treatment with high-potency topical corticosteroids can also support its diagnosis. Differential diagnosis of EPDS is various and difficult. Crusted plaques and pustules on the scalp and other areas can mimic infectious conditions, such as impetigo, bacterial folliculitis, folliculitis decalvans, and atypical tinea capitis [6]. Microbiologic cultures are essential in obscure cases. Infectious diseases, pemphigus foliaceous, pyoderma gangrenosum, and malignant conditions may be considered [7]. Because of the chronic progress and potential cutaneous carcinogenesis, nonmelanoma skin cancer in the setting of EPDS has been reported, indicating the importance of prompt biopsy in cases that show signs suspicious of malignant change [8].
Topical corticosteroids, topical calcineurin inhibitors, and topical photodynamic therapy are considered first-line choices [9]. If the treatment is not effective, other therapies should be considered, including dapsone, isotretinoin, acitretin, calcipotriol, silicone gels, oral zinc sulfate, cyclosporine, and Janus kinase inhibition [5, 10]. Some novel treatments have been reported. Aminolevulinic acid photodynamic therapy can be used as monotherapy for EPDS [11]. In the case of a chronic wound resistant to traditional therapy for EPDS (ultrapotent topical steroids), umbilical remnant allograft has \ been used effectively [12].
In conclusion, EPDS is a chronic inflammatory dermatosis that is usually caused by trauma or sunburn. The crusted plaques and pustules, seen in infectious conditions, often lead to misdiagnosis and delayed treatment. Biopsy and microbiologic cultures are the keys to excluding relevant diseases. Traditional therapies, such as topical corticosteroids and calcineurin inhibitors, are usually effective in the treatment of EPDS.
References
Author notes
Potential conflicts of interest. The authors: No reported conflicts of interest. Both authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
