Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2024;14(4):e2024233 1 Ecthyma Gangrenosum Secondary to Panton-Valentine Leukocidin–Secreting Staphylococcus aureus in an Immunocompetent Patient François-Xavier Blanchet1, Marion Delannoy1, Christine Forasassi1, Juliette Fontaine1, Fabienne Carre2, Dorothée Chopin3, Hester Colboc1 1 Department of Geriatric - wound and healing, Rothschild Hospital, Sorbonne University, Paris, France 2 Otorhinolaryngology Department, Pitié-Salpêtrière Hospital, Sorbonne University, Paris, France 3 Infectious Diseases Department, Saint Antoine Hospital, Sorbonne University, Paris, France Key words: ecthyma gangrenosum, methicillin-sensitive Staphylococcus aureus, Panton-Valentine leukocidin, immunocompetent patient Citation: Blanchet FX, Delannoy M, Forasassi C, et al. Ecthyma Gangrenosum Secondary to Panton-Valentine Leukocidin–Secreting Staphylococcus aureus in an Immunocompetent Patient. Dermatol Pract Concept. 2024;14(4):e2024233. DOI: https://doi.org/10.5826/ dpc.1404a233 Accepted: June 3, 2024; Published: October 2024 Copyright: ©2024 Blanchet et al. This is an open-access article distributed under the terms of the Creative Commons Attribution- NonCommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited. Funding: None. Competing Interests: None. Authorship: All authors have contributed significantly to this publication. Corresponding Author: François-Xavier Blanchet, Department of Geriatric - wound and healing, Rothschild Hospital, APHP, Paris, France. Email: francois-xavier.blanchet@aphp.fr Introduction Ecthyma gangrenosum (EG) is a rare necrotizing vasculitis primarily caused by Pseudomonas aeruginosa sepsis in im- munocompromised patients [1]. It is associated with a severe prognosis, with mortality rates ranging from 20% to 77%. We report a case of EG due to Panton-Valentine leukocidin (PVL)-secreting methicillin-sensitive Staphylococcus aureus (MSSA) in an immunocompetent patient. Case Presentation A 77-year-old patient with no history presented with a pro- tuberant necrotic purulent and very painful posterior cervi- cal lesion that had been evolving for six weeks (Figure 1A) and with scalp furunculosis (Figure 1B). The medical his- tory began five months earlier with a furuncle on the chest, followed by a furuncle in the right inguinal fold and in the buttock crease. Then, following a post-traumatic wound of the neck, the lesion appeared with a highly inflammatory periphery extending over the entire root of the scalp. Despite two courses of antibiotics (pristinamycin 7 days, cloxacillin 10 days), the patient’s condition rapidly deteriorated. EG was suspected, and a pus swab was taken. A cervical CT scan revealed extensive infiltration of superficial tissues of the neck with no identifiable collection. Drainage with washing (Figure 2A) and samples for bacteriological, myco- logical, mycobacterial, and histological testing were taken. The pus swab was positive for MSSA, and in view of this atypical clinical presentation, the PVL test was performed 2 Research Letter | Dermatol Pract Concept. 2024;14(4):e2024233 and came back positive. Histological findings were inconclu- sive. We concluded that the patient had non-bacteremic EG secondary to PVL-secreting MSSA. In view of the PVL, treat- ment with clindamycin 600 mg 4 times a day was initiated for 10 days. We also implemented a S. aureus topical decol- onization protocol. After surgical debridement, management consisted of negative pressure therapy (Figure 2B). This atypical clinical presentation led us to conduct a large immunologic analysis, including immunoglobulin subtypes and complete immunophenotyping of circulating lymphocytes, but no immune deficiency was identified. We also suspected the existence of an underlying skin condition that could have served as a gateway, such as Quinquaud’s disease, dissecting cellulitis, or erosive pustular dermatosis of the scalp. However, investigations of such condition have not been carried out yet because the lesions regressed after treatment. Discussion Only few cases of EG have been observed in immunocom- petent patients [2]. Cases of EG secondary to S. aureus (methicillin-resistant or not) have been reported, but only in immunocompromised patients, with PVL screened only once, and tested negative [3,4]. In France, the prevalence of MSSA positive for PVL is approximately 5%, and PVL diagnosis is not automatically performed when S. aureus is detected in microbiology. Furunculosis, multiple lesions, or deep-seated abscess can be found in PVL infections, and their presence should lead to PVL testing [5]. The occurrence of EG secondary to S. aureus in this im- munocompetent patient might be a consequence of PVL’s pathogenicity, involving bacterial invasion of dermal vessel walls and tissue necrosis. Regarding antibiotic therapy, oxa- cillin and other β-lactams increase PVL production, whereas Figure 1. (A) Clinical ecthyma gangrenosum. (B) Scalp furunculosis. Figure 2. (A) One day after surgery. Note the persistence of scalp furunculosis. (B) Six weeks after surgery (and 12 days after negative pressure therapy). Research Letter | Dermatol Pract Concept. 2024;14(4):e2024233 3 clindamycin or linezolid are usually effective against PVL due to their inhibitory action on protein synthesis [6]. We report an atypical case of EG secondary to PVL- secreting MSSA in an immunocompetent patient. 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