Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2024;14(2):e2024102 1 Human Cutaneous Dirofilariasis Caused by Dirofilaria repens Victoria Mattutzu1, Céline Nourrisson2,3, Clément Theis4, Carole Chevenet1, Philippe Poirier2,3, Maxime Moniot2 1 Department of Pathological Anatomy and Cytology, University Hospital Center of Clermont-Ferrand, France 2 Department of Parasitology-Mycology, University Hospital Center of Clermont-Ferrand, 3IHP, France 3 Microbes, Intestin, Inflammation et Susceptibilité de l’Hôte (M2iSH), UMR Inserm/Université Clermont Auvergne U1071, USC INRA 2018, France 4 Department of Infectious and Tropical Diseases, University Hospital Center of Clermont-Ferrand, France Citation: Mattutzu V, Nourrisson C, Theis C, Chevenet C, Poirier P, Moniot M. Human Cutaneous Dirofilariasis Caused by Dirofilaria repens. Dermatol Pract Concept. 2024;14(2):e2024102. DOI: https://doi.org/10.5826/dpc.1402a102 Accepted: September 7, 2023; Published: April 2024 Copyright: ©2024 Mattutzu 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: Dr Maxime Moniot, Service de Parasitologie Mycologie, 58 rue Montalembert, CHU Gabriel Montpied, 63003 Clermont-Ferrand Cedex 1, France. Phone number: +33 (0)4 73 75 01 95 / Fax number: +33 (0)4 73 75 01 96 Email: mmoniot@chu-clermontferrand.fr Case Presentation A 63-year-old female was seen with a purplish subcutaneous nodule located above the glabel and measuring 6 mm in di- ameter. The lesion had a rapid onset and was followed, two days later, by a wing nose edema, suggestive of granuloma. The patient had no particular medical or travel history. The biological work-up did not show abnormality. Histological exam revealed a granulomatous reaction of the hypodermis, partly suppurated, with an adult worm (Figure 1A). Section of the worm measuring bout 500 µm showed the genital tubes, the muscle layer and a thick cuticle of 12 µm, lam- inated, with longitudinal striation (Figure 1B). Dirofilaria repens was suspected and confirmed by sequencing [1]. In addition to the surgical excision, the patient received a single dose of ivermectine, with no sign of recurrence six weeks later. Teaching Point Dirofilariasis is a cosmopolitan mosquito-transmitted dis- ease involving nematodes of the Dirofilaria genus. Both D. repens and D. immitis are endemic in the Mediterranean region. The definitive hosts of D. repens are canids and rarely felids, Human being accidental host. Dirofilaria re- pens usually manifests as either a wandering worm in the subcutaneous tissue or a granulomatous nodule, mostly 2 Image Letter | Dermatol Pract Concept. 2024;14(2):e2024102 located in ocular and facial regions, whereas D. immitis usu- ally causes pulmonary diseases. In the subcutaneous form, the elevation of blood eosinophils is inconstant. Surgical re- moval of the nodule is the definitive and curative treatment of dirofilariasis. References 1. Riebenbauer K, Weber PB, Walochnik J, et al. Human diro- filariosis in Austria: the past, the present, the future. Parasit Vectors. 2021;14(1):227. DOI: https://doi.org/10.1186/s13071- 021-04696-4 Figure 1. Microscopic examination of the excised nodule at the time of diagnosis after H&E staining. (A) Surperficial dermis and epidermis with sections of the worm in surface (×100 magnification); (B) Section of the worm showing the genital tubes (a), the muscle layer (b), the cuticle with characteristic external longitudinal ridges (c) (×400 magnification).