Erosive pustular dermatosis of the scalp following topical methylaminolaevulinate photodynamic therapy

To the Editor: Erosive pustular dermatosis of the scalp (EPDS) is a rare inflammatory disease of unknown etiology that usually occurs in the elderly. It is characterized by sterile pustules, chronic crusted erosions, cicatricial alopecia, and skin atrophy.A 93-year-old, otherwise healthy female presented to our department with a 2-month history of eroded, pustular, and crusted lesions limited to the scalp. According to the referral notes, she had long standing female-type androgenetic alopecia, and had actinic keratoses on the scalp that were treated with two sessions of topical methylaminolaevulinate photodynamic therapy (MAL-PDT), with improvement of the condition. The patient had superficial curettage of the lesions before the first session, followed by the application of methylaminolaevulinate cream (Metvix; Galderma, Fort Worth, TX) for 3 hours under an occlusive, light-protecting dressing; the area was then irradiated with 75 J/cm2 of red light. The photodynamic therapy was repeated 1 week later. Twenty-eight days after the first treatment, burning erosions developed, extending slowly but progressively. Treatment with topical antibiotics (fusidic acid cream and mupirocin) and systemic antibiotics (amoxicillin/clavulanate) was unsuccessful.The physical examination revealed multiple pustules, erosions, scales, and crusts on the frontoparietal and temporoparietal scalp; gentle removal of the crusts revealed a moist, atrophic surface with telengiectasias and minute erosions exuding yellowish seropurulent material. Areas of scarring alopecia were also evident (Fig 1). The remainder of the skin examination was essentially normal, with no features of a blistering disorder or psoriasis. No clinical evidence of the original actinic keratoses was detected.Cultures from the pustules and erosions failed to show bacterial or mycological growth. Routine laboratory blood tests were normal except for elevated values of markers of inflammation (erythrocyte sedimentation rate, C-reactive protein, and hypergammaglobulinemia); autoantibodies (antinuclear antibodies, rheumatoid factor, thyroglobulin, and microsomal antibodies) were negative. A histologic examination of a 3-mm punch biopsy showed a dense, mainly perifollicular, dermal infiltrate of neutrophils and lymphocytes, with a loss of normal collagen architecture, vasodilatation, and angiogenesis (Fig 2). There was no evidence of malignancy or vasculitis, and a periodic acid-Schiff stain was negative.Fig 2Dense infiltrate of neutrophils and lymphocytes in the reticular dermis and around hair follicles, with a loss of normal collagen architecture and associated vasodilatation and angiogenesis. (Hematoxylin–eosin stain; original magnification: ×40.)View Large Image Figure ViewerDownload Hi-res image Download (PPT)The clinical and histopathologic features were consistent with a diagnosis of EPDS. The patient was treated with oral methylprednisolone (16 mg/day with progressive tapering) in combination with topical gentamycin-betamethasone cream, resulting in marked improvement of lesions and partial resolution of the cutaneous atrophy at 3 months of follow-up. Residual scarring alopecia was evident.Since the first report by Pye et al.1Pye R.J. Peachey R.D. Burton J.L. Erosive pustular dermatosis of the scalp.Br J Dermatol. 1979; 100: 559-566Crossref PubMed Scopus (128) Google Scholar in 1979, several cases of EPDS have been reported. The disease is an uncommon condition that occurs mainly in the elderly, with a slight preference for females. It characteristically develops in atrophic sun-damaged skin. It is characterized by sterile pustules with a nonspecific inflammatory infiltrate. It must be differentiated from folliculitis decalvans, pyoderma gangrenosum, and cicatricial pemphigoid.2Grattan C.E. Peachey R.D. Boon A. Evidence for a role of local trauma in the pathogenesis of erosive pustular dermatosis of the scalp.Clin Exp Dermatol. 1988; 13: 7-10Crossref PubMed Scopus (83) Google Scholar The nonspecific histopathologic pattern, the evolution leading to scarring alopecia, and the resistance to antibiotics, with response to steroids, favor the diagnosis.Although the pathophysiologic mechanisms remain obscure, it is generally believed that local trauma acts as a triggering factor. EPDS has been widely reported in the literature following the treatment of actinic keratoses or squamous cell carcinoma with topical 5% fluorouracil or tretinoin. It may also occur days to years after incidental blunt trauma, surgery, cryotherapy, or radiotherapy.2Grattan C.E. Peachey R.D. Boon A. Evidence for a role of local trauma in the pathogenesis of erosive pustular dermatosis of the scalp.Clin Exp Dermatol. 1988; 13: 7-10Crossref PubMed Scopus (83) Google Scholar, 3Van Exel C.E. English J.C. Erosive pustular dermatosis of the scalp and nonscalp.J Am Acad Dermatol. 2007; 57: S11-S14Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar, 4Wu C.Y. Chen G.S. Lan C.C.E. Erosive pustular dermatosis of the scalp after gefitinib and radiotherapy for brain metastases secondary to lung cancer.Clin Exp Dermatol. 2007; 33: 106-107PubMed Google ScholarResponse to treatment is variable. Potent topical steroids have been widely used in EPDS, and anecdotal reports have described a partial response to oral isotretinoin, dapsone, and nimesulide. Recently, calcipotriol cream and tacrolimus ointment have been used successfully as alternative therapies.5Cenkowsky M.J. Silver S. Topical tacrolimus in the treatment of erosive pustular dermatosis of the scalp.J Cutan Med Surg. 2007; 11: 222-225PubMed Google ScholarTo our knowledge, none of the previous reported side effects of MAL-PDT have included chronic pustules, scale crusts, and nonhealing erosions. In our opinion, EPDS should be considered in any subject developing a chronic inflammatory response after MAL-PDT. To the Editor: Erosive pustular dermatosis of the scalp (EPDS) is a rare inflammatory disease of unknown etiology that usually occurs in the elderly. It is characterized by sterile pustules, chronic crusted erosions, cicatricial alopecia, and skin atrophy. A 93-year-old, otherwise healthy female presented to our department with a 2-month history of eroded, pustular, and crusted lesions limited to the scalp. According to the referral notes, she had long standing female-type androgenetic alopecia, and had actinic keratoses on the scalp that were treated with two sessions of topical methylaminolaevulinate photodynamic therapy (MAL-PDT), with improvement of the condition. The patient had superficial curettage of the lesions before the first session, followed by the application of methylaminolaevulinate cream (Metvix; Galderma, Fort Worth, TX) for 3 hours under an occlusive, light-protecting dressing; the area was then irradiated with 75 J/cm2 of red light. The photodynamic therapy was repeated 1 week later. Twenty-eight days after the first treatment, burning erosions developed, extending slowly but progressively. Treatment with topical antibiotics (fusidic acid cream and mupirocin) and systemic antibiotics (amoxicillin/clavulanate) was unsuccessful. The physical examination revealed multiple pustules, erosions, scales, and crusts on the frontoparietal and temporoparietal scalp; gentle removal of the crusts revealed a moist, atrophic surface with telengiectasias and minute erosions exuding yellowish seropurulent material. Areas of scarring alopecia were also evident (Fig 1). The remainder of the skin examination was essentially normal, with no features of a blistering disorder or psoriasis. No clinical evidence of the original actinic keratoses was detected. Cultures from the pustules and erosions failed to show bacterial or mycological growth. Routine laboratory blood tests were normal except for elevated values of markers of inflammation (erythrocyte sedimentation rate, C-reactive protein, and hypergammaglobulinemia); autoantibodies (antinuclear antibodies, rheumatoid factor, thyroglobulin, and microsomal antibodies) were negative. A histologic examination of a 3-mm punch biopsy showed a dense, mainly perifollicular, dermal infiltrate of neutrophils and lymphocytes, with a loss of normal collagen architecture, vasodilatation, and angiogenesis (Fig 2). There was no evidence of malignancy or vasculitis, and a periodic acid-Schiff stain was negative. The clinical and histopathologic features were consistent with a diagnosis of EPDS. The patient was treated with oral methylprednisolone (16 mg/day with progressive tapering) in combination with topical gentamycin-betamethasone cream, resulting in marked improvement of lesions and partial resolution of the cutaneous atrophy at 3 months of follow-up. Residual scarring alopecia was evident. Since the first report by Pye et al.1Pye R.J. Peachey R.D. Burton J.L. Erosive pustular dermatosis of the scalp.Br J Dermatol. 1979; 100: 559-566Crossref PubMed Scopus (128) Google Scholar in 1979, several cases of EPDS have been reported. The disease is an uncommon condition that occurs mainly in the elderly, with a slight preference for females. It characteristically develops in atrophic sun-damaged skin. It is characterized by sterile pustules with a nonspecific inflammatory infiltrate. It must be differentiated from folliculitis decalvans, pyoderma gangrenosum, and cicatricial pemphigoid.2Grattan C.E. Peachey R.D. Boon A. Evidence for a role of local trauma in the pathogenesis of erosive pustular dermatosis of the scalp.Clin Exp Dermatol. 1988; 13: 7-10Crossref PubMed Scopus (83) Google Scholar The nonspecific histopathologic pattern, the evolution leading to scarring alopecia, and the resistance to antibiotics, with response to steroids, favor the diagnosis. Although the pathophysiologic mechanisms remain obscure, it is generally believed that local trauma acts as a triggering factor. EPDS has been widely reported in the literature following the treatment of actinic keratoses or squamous cell carcinoma with topical 5% fluorouracil or tretinoin. It may also occur days to years after incidental blunt trauma, surgery, cryotherapy, or radiotherapy.2Grattan C.E. Peachey R.D. Boon A. Evidence for a role of local trauma in the pathogenesis of erosive pustular dermatosis of the scalp.Clin Exp Dermatol. 1988; 13: 7-10Crossref PubMed Scopus (83) Google Scholar, 3Van Exel C.E. English J.C. Erosive pustular dermatosis of the scalp and nonscalp.J Am Acad Dermatol. 2007; 57: S11-S14Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar, 4Wu C.Y. Chen G.S. Lan C.C.E. Erosive pustular dermatosis of the scalp after gefitinib and radiotherapy for brain metastases secondary to lung cancer.Clin Exp Dermatol. 2007; 33: 106-107PubMed Google Scholar Response to treatment is variable. Potent topical steroids have been widely used in EPDS, and anecdotal reports have described a partial response to oral isotretinoin, dapsone, and nimesulide. Recently, calcipotriol cream and tacrolimus ointment have been used successfully as alternative therapies.5Cenkowsky M.J. Silver S. Topical tacrolimus in the treatment of erosive pustular dermatosis of the scalp.J Cutan Med Surg. 2007; 11: 222-225PubMed Google Scholar To our knowledge, none of the previous reported side effects of MAL-PDT have included chronic pustules, scale crusts, and nonhealing erosions. In our opinion, EPDS should be considered in any subject developing a chronic inflammatory response after MAL-PDT.