Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2024;14(3):e2024164 1 Pigmented Demodicosis: Non-Invasive Skin Imaging of a Rare Entity Stefania Guida1,2, Claudia Lasagni3, Silvana Ciardo3, Francesca Farnetani3, Caterina Longo3,4, Giovanni Pellacani5 1 Vita-Salute San Raffaele University, Milan, Italy 2 Dermatology Clinic, IRCCS San Raffaele Scientific Institute, Milan, Italy 3 Dermatology Unit, Surgical, Medical and Dental Department of Morphological Sciences related to Transplant, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy 4 Centro Oncologico ad Alta Tecnologia Diagnostica, Azienda Unità Sanitaria Locale-IRCCS di Reggio Emilia, Reggio Emilia, Italy 5 Dermatology Unit, Department of Clinical Internal Anesthesiologic Cardiovascular Sciences, Sapienza University of Rome, Rome, Italy Citation: Guida S, Lasagni C, Ciardo S, Farnetani F, Longo C, Pellacani G. Pigmented Demodicosis: Non- Invasive Skin Imaging of a Rare Entity. Dermatol Pract Concept. 2024;14(3):e2024164. DOI: https://doi.org/10.5826/dpc.1403a164 Accepted: February 14, 2024; Published: July 2024 Copyright: ©2024 Guida 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. Stefania Guida and Claudia Lasagni equally contributed. Corresponding Author: Stefania Guida, Vita-Salute San Raffaele University, Via Olgettina 58, 20132 Milan, Italy. Email: guida.stefania@hsr.it Case report A 32-year-old, Fitzpatrick phototype III woman presented with a 10-year history of diffuse facial hyperpigmentation, associated with slight burning sensation. The patient did not have any comorbidities but her previous medical history re- vealed episodes of intense ultraviolet exposure. Her facial hyperpigmentation was previously interpreted as melasma so she underwent topical and medical peeling treatments, without any improvements. At clinical observation, the patient showed diffused hy- perpigmentation on the face (Figure 1A). Dermoscopy re- vealed perifollicular hyperpigmentation on an erythematous background, with dilated follicular openings and structures suggestive for demodex tails (Figure 1B). Additionally, RCM confirmed the presence of demodex (Figure 1 C). Due to recent description of super high magnification dermoscopy pattern corresponding to demodex presence inside the hair follicle, we decided to further explore this rare case of pig- mented demodicosis (PD), highlighting the presence of white linear structures inside hair follicles (Figure 1 D) [1]. Treat- ment with topical ivermectin was suggested. Teaching Point PD diagnosis has been probably underestimated in the past due to a difficult differential diagnosis with lupus, contact dermatitis, idiopathic hyperpigmentation [2]. Hyperpig- mentation in PD has been associated to demodex, even if the pathogenesis has yet to be defined, as confirmed by 2 Image Letter | Dermatol Pract Concept. 2024;14(3):e2024164 the improvement of hyperpigmentation after ivermectin treatment. In conclusion, the clinical combination of hyperpigmen- tation, erythema and rough skin surface should rise the sus- picion of PD, that should be confirmed with the presence of demodex, revealed with non-invasive skin imaging in our case. Clinicians should be aware about this clinical entity and demodicosis should be added to the list of causes of facial hyperpigmentation. References 1. Cinotti E, Bertello M, Donelli C, et al. Super-high magnifi- cation dermoscopy can detect Demodex folliculorum. J Eur Acad Dermatol Venereol. 2023;37(1):e96-e97. DOI: 10.1111 /jdv.18496. PMID: 35964306. 2. Feuerman H, Atzmony L, Glick M, et al. Pigmented demodicidosis - an under-recognized cause of facial hyperpigmentation. Int J Dermatol. 2022;61(5):564-569. DOI: 10.1111/ijd.15992. PMID: 34897670. Figure 1. (A) Clinical picture in frontal view. (B) Dermoscopic picture showing dilated hair follicles (blue arrows) and demodex tails (green arrows). (C) Reflectance confocal microscopy highligting demodex inside the hair follicle (a detail in the upper white square), melanophages, vessels, bulbous projections (white star). (D) Super high magnification picture revealing demodex inside the hair follicle, faded structures, and vessels.