Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2025;15(2):5642 1 Unusual Presentation of Hertoghe’s Sign and Its Trichoscopic Features Nino Khutsishvili1, Nino Lortkipanidze1, Salome Getsadze2 1 Department of Dermatology and Sexually Transmitted Diseases, David Tvildiani Medical University, Tbilisi, Georgia 2 Department of Dermatology, Petre Shotadze Tbilisi Medical Academy, Tbilisi, Georgia Citation: Khutsishvili N, Lortkipanidze N, Getsadze S. Unusual Presentation of Hertoghe’s Sign and Its Trichoscopic Features. Dermatol Pract Concept. 2025;15(2):5642. DOI: https://doi.org/10.5826/dpc.1502a5642 Accepted: April 4, 2025; Published: April 2025 Copyright: ©2025 Khutsishvili 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: Nino Khutsishvili, MD, David Tvildiani Medical University, 2/6 Ljubljana, 0159, Tbilisi, Georgia. ORCID ID: 0009-0009-7512-1169. E-mail: ninokhutsishvili87@yahoo.com Case Presentation A 21-year-old man with a history of late-onset atopic derma- titis at the age of 15 reported a prominent flare-up of the dis- ease for the past three months and noted eyebrow thinning during this period. In addition to the clinical signs character- istic of atopic dermatitis, physical examination revealed uni- lateral hair thinning involving the entire eyebrow (Figure 1). No shedding or complete hair loss was found in other parts of the body. The patient had no history of alopecia areata, seborrheic dermatitis, or infection. Despite the affected area being notably pruritic, he denied rubbing or scratching it. We performed laboratory tests to rule out hypothyroidism. Hair thinning limited to the lateral one-third of both eyebrows is known as Hertoghe’s sign. It is predominantly observed in atopic dermatitis and hypothyroidism [1]. There are no disease-specific trichoscopic features documented for this condition. In our case, trichoscopy of the affected eye- brow showed: decreased number of terminal hairs, diffuse erythema, scaling, monilethrix-like hairs, pili torti, hairs bro- ken at different lengths, black dots, micro-exclamation mark hairs, and empty hair follicles. Teaching Point If a physician encounters isolated loss of eyebrow as a stand- alone condition, it is essential to consider Hertoghe’s sign as a differential diagnosis, making a detailed description of all trichoscopic findings much more important. Our patient had an unusual presentation of this sign - unilateral hair thinning involving the entire eyebrow, rather than the typical presen- tation, which is limited to the lateral one-third [2]. 2 Image Letter | Dermatol Pract Concept. 2025;15(2):5642 References 1. Nguyen B, Hu JK, Tosti A. Eyebrow and Eyelash Alopecia: A Clinical Review. Am J Clin Dermatol. 2023;24(1):55-67. DOI: 10.1007/s40257-022-00729-5. PMID: 36183302. 2. Borzutzky A, Tejos-Bravo M, Venegas LF, Iturriaga C. Hertoghe’s Sign in Atopic Dermatitis. J Pediatr. 2020;226:299. DOI: 10.1016 /j.jpeds.2020.06.088. PMID: 32629013 Figure 1. (A) Significant difference in the number of hair shafts between the affected and unaffected eyebrows. (B,C,D) trichoscopic images of affected eyebrow: diffuse erythema, scaling (yellow ring), monilethrix-like hairs (black arrows), black dots (white rings), empty hair follicles (black rings), pili torti (green arrows), hairs broken at different lengths (green rings), micro-exclamation mark hair (blue arrow).