Pityriasis amiantacea in erosive pustular dermatosis of the scalp: A report of three cases

Abstract

Erosive pustular dermatosis is an uncommon chronic inflammatory condition of the scalp characterized by crusted, erosive plaques and subsequent cicatricial alopecia. Management of erosive pustular dermatosis remains challenging, and various treatments have been described in the literature with inconsistent results. Herein, we report three cases of erosive pustular dermatosis with a pityriasis amiantacea-like presentation in the context of poor scalp hygiene. All patients presented with thick adherent crusts on the scalp that were refractory to multiple therapies. Significant clinical improvement was achieved by addressing scalp hygiene through regular cleansing and the use of dilute sodium hypochlorite compresses, in combination with topical corticosteroids as well as systemic and topical antibiotics. Our findings highlight the importance of addressing scalp hygiene to ameliorate treatment outcomes and minimize the risk of recurrence in patients with erosive pustular dermatosis, especially those with a pityriasis amiantacea-like presentation.

Introduction

Erosive pustular dermatosis (EPD) of the scalp is a rare chronic inflammatory disorder primarily affecting elderly individuals. Characteristic findings include pustules, erosions, crusted plaques, and skin atrophy. ¹ Patients often experience relapsing disease. ² Skin lesions may become colonized and, more rarely, secondarily infected with bacteria.^3,4 The goal of treatment is to prevent scarring alopecia.^1–3

Pityriasis amiantacea (PA) is an uncommon scalp condition characterized by thick, asbestos-like adherent scales that bind to hair shafts. PA is a distinctive reaction pattern of the scalp that may present as a clinical manifestation or as a complication of inflammatory and infectious conditions, including bacterial and fungal infections.^5,6 Although PA can occur with other cicatricial alopecias, such as folliculitis decalvans and lichen planopilaris, to our knowledge, its occurrence in EPD has not yet been reported. ⁵

We describe three cases of EPD of the scalp complicated by PA-like impetiginization associated with poor scalp hygiene.

Case report

Case 1: A 79-year-old female presented with a 4-year history of an erosive, alopecic plaque with hemorrhagic adherent crusts on the vertex (Figure 1(a)). A biopsy excluded malignancy. She avoided scalp washing, fearing it would worsen her condition. Initial treatment with high-potency topical corticosteroids and adalimumab provided no significant improvement. A 6-week course of systemic clindamycin and rifampin, with twice-daily topical fusidic acid and betamethasone valerate, was then initiated. She was also advised to wash her scalp and apply dilute sodium hypochlorite compresses to the affected area daily. This regimen led to the resolution of her lesion, leaving an atrophic alopecic plaque (Figure 1(b)). Six months later, a recurrence affecting 30% of the originally involved area was successfully managed with improved scalp hygiene and application of dapsone and clobetasol propionate. She remained disease-free after 1 year of follow-up.

Figure 1.

Clinical images of erosive pustular dermatosis of the scalp before and after treatment. Case 1: Baseline presentation in March 2023 (a) and following treatment with systemic rifampin and clindamycin, topical fusidic acid and betamethasone valerate, and measures to improve scalp hygiene in April 2023 (b). Case 2: Baseline presentation in April 2024 (c) and following treatment with systemic rifampin and clindamycin, topical fusidic acid and betamethasone valerate, and measures to improve scalp hygiene in July 2024 (d). Case 3: Baseline presentation in December 2022 (e) and following treatment with topical dapsone, fusidic acid, and betamethasone valerate, and measures to improve scalp hygiene in February 2023 (f).

Case 2: An 88-year-old male with a history of scalp basal cell carcinoma and androgenetic alopecia presented with a 6-month history of crusted yellow-green plaques of the left parietal region and vertex (Figure 1(c)). Previous treatments with topical tazarotene, fusidic acid, and betamethasone valerate had been ineffective. A 4-week course of systemic clindamycin and rifampin, along with topical fusidic acid and betamethasone valerate and daily dilute sodium hypochlorite soaks, resulted in healing of 90% of his scalp lesions (Figure 1(d)).

Case 3: A 94-year-old male, with a history of androgenetic alopecia and actinic keratoses of the scalp treated with topical 5-fluorouracil, presented with thick, adherent plaques on the frontal scalp (Figure 1(e)). Treatment with topical clobetasol propionate, topical dapsone, and systemic acitretin was unsuccessful. Twice-daily application of topical fusidic acid, betamethasone valerate, and dapsone, combined with dilute sodium hypochlorite compresses, led to the resolution of 90% of lesions after 2 months (Figure 1(f)). Although recurrent lesions developed during follow-up, they were managed successfully with high-potency topical corticosteroids, topical antibacterial agents, and daily antibacterial scalp washes.

Discussion

In summary, we found that poor scalp hygiene, by promoting bacterial colonization, contributed to the worsening of EPD in three patients, all of whom exhibited a PA-like presentation.

Various therapies have been reported to treat EPD, including high-potency topical corticosteroids, topical steroid-sparing agents, and systemic medications, albeit with variable success.^1,2,7–9 Treatment with antimicrobial agents is usually ineffective unless there is secondary infection.^8,9 Some authors recommend debridement of crusted plaques to increase penetration of topical medications.^8,10 Proper wound care is also advised, as it encourages wound healing and helps prevent secondary infections. ¹⁰

Improvement of scalp hygiene and treatment of colonization led to near-complete resolution of lesions in our patients. This was achieved with a combination of regular scalp washes and application of dilute sodium hypochlorite compresses, along with topical and systemic antibiotics.