Erosive Pustular Dermatosis of the Scalp

Abstract

143Erosive pustular dermatosis of the scalp (EPDS) is a rare condition characterized by sterile pustules and erosions with superficial crusts that typically develop in long-standing atrophic sun-damaged skin of elderly patients; it may lead to scarring alopecia in cases with extensive involvement. Other names include “Chronic atrophic dermatosis of the scalp and extremities” since involvement of the leg as a chronic vegetating pyoderma has been reported in patients with chronic venous insufficiency. Atrophic (actinic) skin seems to be a prerequisite for the development of EPDS. Trauma and tissue damage seem to play the triggering role: preceding herpes zoster, iatrogenic injury caused by cryotherapy, carbon dioxide laser, topical chemotherapy for field cancerization, excisional surgery, imiquimod, tretinoin, grafting after surgery, x-ray radiation, and topical photodynamic therapy have been reported in association. The most common location is the vertex and the clinical presentation ranges from a few erosive, scaly lesions to crusted and hemorrhagic plaques, mimicking pustular pyoderma gangrenosum (Figures 21.1 and 21.2). Figure 21.1 (A, B) EPDS in a patient with sun-damaged skin which developed after partial thickness skin graft for squamous cell carcinoma. (Courtesy of Giselle Martins, MD.) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429457609/a1a07c34-5530-453d-aca4-02e4ee680a4a/content/fig21_1.tif"/> Figure 21.2 Diffuse erythema and yellow scale-crusts on clinical exam. (Courtesy of Giselle Martins, MD.) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429457609/a1a07c34-5530-453d-aca4-02e4ee680a4a/content/fig21_2.tif"/> The lesions usually have a linear distribution. There is variant with hypergranulation overlying the erosions. The pathogenies remains unclear. Factors such as loss of normal epidermal barrier and tissue damage may induce a reaction of immune dysregulation in the hair follicle and therefore some consider EPDS a neutrophilic superficial folliculitis, part of the spectrum of pathergic neutrophilic dermatoses such as pyoderma gangrenosum. On trichoscopy, there are non-specific features but distinctions between active and chronic cases can be made according to Starace et al. Active disease: The most characteristic finding is the anagen bulb visible thought the atrophic skin; other features include yellow-hemorrhagic crusts, pili torti, dystrophic hairs and mini-tufts of 2–4 hairs emerging together from the same ostium (Figures 21.3 and 21.4) Figure 21.3 Yellow crusts, diffuse erythema in active disease (×20). (Courtesy of Giselle Martins, MD.) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429457609/a1a07c34-5530-453d-aca4-02e4ee680a4a/content/fig21_3.tif"/> Figure 21.4 Pustules and yellow exudate (×20). (Courtesy of Giselle Martins, MD.) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429457609/a1a07c34-5530-453d-aca4-02e4ee680a4a/content/fig21_4.tif"/> Chronic disease: Significantly atrophic skin with visible anagen bulbs, lack of follicular ostia (Figure 21.5), yellow exudate Figure 21.5 Loss of follicular ostia, milky white areas of scarring, broken hairs, pili torti-like hairs (×20). (Courtesy of Giselle Martins, MD.) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429457609/a1a07c34-5530-453d-aca4-02e4ee680a4a/content/fig21_5.tif"/> Vessels in EPDS: Enlarged and polymorphous vessels have been described, particularly in the hypergranulation variant