Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2024;14(1):e2024029 1 Topical Ivermectin for Permethrin-Resistant Scabies: A Useful Application Laura Gnesotto1, Mario Cutrone2, Carlo Mazzatenta3, Andrea Bassi3, Vincenzo Piccolo4, Andrea Sechi2 1 Dermatology Unit, Department of Medicine DIMED, University of Padova, Padova, Italy 2 Pediatric Dermatology, Ospedale dell’Angelo Venezia, Ospedale San Bortolo Vicenza, Italy 3 UO Dermatology- Azienda USL Toscana Nord Ovest, Lucca, Italy 4 Dermatology Unit, University of Campania, Naples, Italy Citation: Gnesotto L, Cutrone M, Mazzatenta C, Bassi A, Piccolo V, Sechi A. Topical Ivermectin for Permethrin-Resistant Scabies: A Useful Application. Dermatol Pract Concept. 2024;14(1):e2024029. DOI: https://doi.org/10.5826/dpc.1401a29 Accepted: June 8, 2023; Published: January 2024 Copyright: ©2024 Gnesotto 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: Andrea Sechi, Pediatric Dermatology, Ospedale San Bortolo, Vicenza 36100, Italy. E-mail: andrea.sechi@aulss8.veneto.it Case Presentation A two-year-old child presented with multiple erythematous papulo-nodular lesions on axillary folds and palms. Mites were noted with dermoscopy, confirming a diagnosis of sca- bies. The patient was initially treated with permethrin 5% cream for three consecutive days and again one week later, without efficacy. Therefore, topical benzyl benzoate 25% was applied thrice over a 24-hour period and repeated after a week. At physical examination, no mites were noted on the body, except for the scalp. Thus, an off-label administration of ivermectin cream 1% was prescribed, once a week for two weeks. Improvement was evident immediately after the first application, with complete remission of scalp lesions. No side effects or irritation were referred by the parents, and no relapse occurred at one-month follow-up. Teaching Point Scabies is a highly contagious infection by Sarcoptes scabiei var. hominis. Permethrin 5% cream is the first-line therapy; however, the emergence of permethrin-resistant scabies is a growing concern. Alternative topical treatments for chil- dren, including benzyl benzoate 25%, sulfur preparations, and crotamiton 10% cream, may cause irritation or sys- temic toxicity [1]. Ivermectin selectively targets and binds to glutamate-gated chloride channels in the nervous system of scabies mites; this interaction leads to increased permeabil- ity of chloride ions, hyperpolarization of nerve and muscle cells, and ultimately, paralysis of the parasite [1]. The use of oral ivermectin was contraindicated since our patient weighed less than 15 Kg [1]. It is important to consider drug resistance or the involvement of "unusual" sites such as the 2 Image Letter | Dermatol Pract Concept. 2024;14(1):e2024029 periungual area or the scalp, when recalcitrant scabies is sus- pected. Although there are limited studies on the safety and efficacy of topical ivermectin 1% cream for classic scabies in adults, successful treatment has been reported in a few infants [2]. References 1. Thompson R, Westbury S, Slape D. Paediatrics: how to man- age scabies. Drugs Context. 2021;10:2020-12-3. DOI: 10.7573 /dic.2020-12-3. PMID: 33828606. PMCID: PMC8007207. 2. Bassi A, Piccolo V, Argenziano G, Mazzatenta C. Topical ivermectin: an off-label alternative to treat neonatal Scabies in the era of permethrin resistance. J Eur Acad Dermatol Venereol. 2022; 36(7):e557-e559. DOI: 10.1111/jdv.18026. PMID: 35188996. Figure 1. (A) A crusted lesion on the scalp was visible during physical examination (yellow box). (B) Trichoscopy revealed the delta-wing jet sign (red arrow) at the end of the contrail sign (red box), which identified the female mite head and burrow, respectively. (C) Clinical resolution of scalp scabies observed 1 month after treatment.