Two Cases of Severe Erosive Pustular Dermatosis Mimicking Infection

Introduction. Erosive pustular dermatosis of the scalp (EPDS) is a noninfectious inflammatory disorder characterized by pustules, erosions, ulcerations, and crusted erythematous plaques that is often associated with mechanical or chemical trauma. While its appearance may mimic infection, its etiology is thought to have an autoimmune component based on responsiveness to immunomodulators. Case Report. Herein, the authors present 2 cases of EPDS that were initially treated as primary infections. In both cases, the wounds did not respond to antimicrobial treatment and led to severe ulceration, exposing cranial bone. Both wounds improved with topical corticosteroid therapy. Conclusions. These cases represent the importance of considering topical steroid treatment and a diagnosis of EPDS after debridement for purulent scalp ulcers.

Erosive pustular dermatosis of the scalp (EPDS) is a rare inflammatory disorder of unclear etiology characterized by sterile pustules, erosions, ulcerations, and crusted erythematous plaques that cause scarring alopecia. It primarily affects older adults with a preference for women and has been associated with preceding mechanical or chemical trauma in areas of actinic damage.¹ The underlying pathogenesis of EPDS is not clearly understood, though it is thought to have an autoimmune etiology based on its responsiveness to immunomodulators.² Histopathologically, EPDS has been characterized by acute and chronic inflammation with the presence of lymphocytes, neutrophils, and occasional foreign body giant cells; fibrosis and scarring; epidermal atrophy; and parakeratosis and compact orthokeratosis.³

The appearance of EPDS lesions and the potential for superinfection with poorly healing wounds may be mistaken for a primary infectious process. Two cases of EPDS from Brigham and Women’s Hospital (Boston, MA) initially treated as primary infections are presented. Neither wound responded to antimicrobial treatment but rather expanded, leading to severe ulceration exposing cranial bone. Both wounds, however, improved dramatically with topical corticosteroid therapy.

An 80-year-old man with a 5-year history of recurrent squamous cell carcinoma (SCC) of the scalp, with multiple Mohs surgeries and poorly healing wounds, presented with scalp lesions lasting 5 months. He had a large ulcer that produced serosanguinous fluid with multiple discrete brown crusts and eschars overlying boggy nodules with yellow to green discharge, and thick waxy yellow crusting of the forehead and bilateral eyebrows. Infection was suspected and the patient was admitted for treatment with intravenous (IV) ceftazidime (2 g every 12 hours for 5 days) along with surgical debridement.

Two years prior to presentation, the patient had a scalp SCC treated with Mohs surgery requiring a partial removal of the calvarium with reconstruction by Juri flap and adjuvant radiation. After this treatment, he had an 18-month period of recurrent eschars, purulent drainage, and red streaking thought to be secondary to infection. Serial wound cultures were obtained, demonstrating Pseudomonas and skin flora, but the patient did not improve despite treatment with multiple courses of antibiotics.

At the time of presentation, a magnetic resonance image showed changes in the soft tissue at the vertex tracking down to the bone. This was thought to represent either an underlying nidus of infection, osteomyelitis of the scalp, or skin breaks related to seborrheic dermatitis in the setting of prior radiation. Culture studies done at the time grew 2 strains of Pseudomonas and coagulase-negative Staphylococcus. He was recommended for inpatient admission for IV ceftazidime (2 g every 12 hours for 5 days) and wound debridement as well as inpatient plastic surgery, wound care, and dermatology consultations. A noncontrast computed tomography scan of the head showed erosion of the frontotemporal bone at the site of the previous debridement. A biopsy of the skin was performed for concern of recurrent SCC, which returned negative, with histopathology demonstrating nonspecific findings of dermal fibrosis and acute and chronic inflammation. Dermatology performed a bedside debridement that revealed healthy granulation tissue and exposed calvarium; a clinical diagnosis of EPDS with secondary infection was made.

The patient was transitioned from IV ceftazidime to oral ciprofloxacin (500 mg twice daily for 7 days), and topical treatment with a 1:1 gentamycin 0.1% and betamethasone 0.05% ointment was initiated. At outpatient follow-up 1 month following hospital discharge, he had complete resolution of active inflammation and signs of infection but still had areas of exposed necrotic bone. Topical betamethasone was discontinued, sharp debridement of necrotic bone was performed, and surgical intervention with skin substitute material was recommended.

An 87-year-old woman was referred to the wound clinic at Brigham and Women’s Hospital for a second opinion of lesions on her right parieto-occipital scalp (Figure 1). The lesions consisted of multiple painful, tender ulcers with purulent discharge and a foul smell that had worsened over 2 months. One ulcer had a crater-like appearance extending down to exposed bone. She had no history of trauma to the area. Her past medical history was significant for multiple nonmelanoma skin cancers with 4 prior Mohs surgeries on the upper and lower extremities with slow-healing wounds.

Three months prior to her referral, her lesions were thought to be shingles of the visual cortex 1 region, for which she was treated with 2 courses of valacyclovir and gabapentin. Another provider had prescribed her topical oxiconazole for a suspected yeast infection. Neither of these treatments were efficacious. Skin biopsies performed showed epidermal and follicular necrosis with acute inflammation, abscess formation, and impetiginized scale-crust. Immunostaining for herpes simplex virus and varicella-zoster virus were negative. With these results, primary infection became less likely, and a diagnosis of EPDS with superinfection was made. Treatment shifted to clobetasol 0.05% ointment twice daily for 4 weeks and a course of levofloxacin 750 mg once daily for 5 days. Wound care consisted of collagenase, halobetasol, calcipotriene, and tacrolimus ointments. She also received acitretin, oral zinc, and vitamin C supplementation.

At 1-month follow-up, she showed significant improvement with complete resolution of inflammation and purulence and complete healing of all ulcers except for the area of exposed bone (Figure 2). She was referred to plastic surgery for consideration of surgical wound closure.

The cases reviewed in this report both represent severe erosive pustular dermatosis with ulceration to the cranium. Both cases were initially thought to be primarily infectious processes and were treated with antimicrobial therapy with little improvement. Ultimately, topical steroid treatment and wound care allowed for substantial healing of ulcerations with surgical management of deep erosions considered in both cases.

This report also represents the presentation of idiopathic EPDS without inciting trauma that may initially mimic an infectious process. In a recent case series of 20 patients with EPDS, Starace et al⁴ found that only 9 of 20 patients had a history of inciting trauma prior to the development of pustules and ulcers. Other reported inciting factors for EPDS include cosmetic resurfacing,⁵ contact dermatitis from prosthetic hair,⁶ hair bleaching,⁷ and hair transplantation.⁸ Other chemical exposures that have been described in the literature include gefitinib,⁹ ingenol mebutate,¹⁰ topical latanoprost,¹¹ and topical minoxidil.¹²

In addition, of the 20 cases described in the aforementioned series,⁴ five were initially thought to be due to tinea capitis and were treated with topical or systemic antifungals. This highlights the trend of EPDS being commonly mistaken for and treated as an infection and the need to consider a diagnosis of EPDS sooner in cases of refractory infection where the host appears unaffected by systemic illness. In the 2 presented cases, earlier consideration of EPDS and immunosuppressive therapy may have prevented the severity of ulceration that prevailed.

The mainstay of EPDS treatment has centered on steroid use and immunomodulatory agents.^13-16 The current standard of care includes a potent class I topical corticosteroid such as halobetasol 0.05%. Second-line agents include systemic prednisone at 1 mg/kg/day tapered over several months, mupirocin ointment, and oral tetracyclines. If no benefit is seen from these, treatment with isotretinoin or dapsone may be indicated.¹⁷ Topical steroid therapy ultimately proved to be efficacious for these 2 patients. Additional treatment modalities that have been suggested recently include biological agents, aminolevulinate photodynamic therapy,¹⁸ silicone gel,¹⁹ and dapsone.

Overall, this case report represents the importance of considering topical steroid treatment and a diagnosis of EPDS after debridement for purulent scalp ulcers.

Affiliation: Brigham and Women’s Hospital, Boston, MA

Correspondence: Ryan S. Din, BS, Research Assistant, Brigham and Women’s Hospital, Dermatology, 75 Francis Street, Boston, MA 02115; ryan_din@hms.harvard.edu

Disclosure: The authors disclose no financial or other conflicts of interest.