Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2024;14(4):e2024275 1 Dermoscopy of Acquired Brachial Cutaneous Dyschromatosis (ABCD) Noemi Plozner1, Fulvio Antoniazzi2, Giuseppe Stinco1, Enzo Errichetti1 1 Institute of Dermatology, “Santa Maria della Misericordia” University Hospital, Udine, Italy 2 Institute of Pathology, Academic Hospital of Udine, Department of Medicine, University of Udine, Udine, Italy Citation: Plozner N, Errichetti E, Stinco G, Antoniazzi F. Dermoscopy of Acquired Brachial Cutaneous Dyschromatosis (ABCD). Dermatol Pract Concept. 2024;14(4):e2024275. DOI: https://doi.org/10.5826/dpc.1404a275 Accepted: July 21, 2024; Published: October 2024 Copyright: ©2024 Plozner 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: Enzo Errichetti, Professor, Institute of Dermatology, “Santa Maria della Misericordia” University Hospital, Piazzale Santa Maria della Misericordia, 15. 33100-Udine, Italy. Phone: (+39) 0432559822. E-mail: enzoerri@yahoo.it Case Presentation A 69-year-old man with a 3-year history of several asymp- tomatic symmetrical light brown hyper- and hypopigmented macules confined to both forearms presented for evaluation (Figure 1A); no other significant mucocutaneous lesions were evident. Past medical history included hypertension treated with calcium channel blockers (felodipine). The patient denied other health problems or other medication intake. Dermoscopic assessment showed dyschromatosis with hyperpigmented (brownish) and hypopigmented struc- tureless areas and linear vessels with reticular distribution (Figure 1B). Skin biopsy revealed minimal hyperkeratosis, epidermal atrophy and basal cell layer hyperpigmenta- tion, dermal edema, and solar elastosis of the superficial dermis, consistent with a diagnosis of acquired brachial cutaneous dyschromatosis (ABCD). Teaching Point ABCD is a newly described disorder presenting with chronic asymptomatic geographic-shaped/reticular gray-brown/ erythematous hypopigmented macules and/or patches of the dorsal aspect of the forearms. A possible correlation with anti- hypertensive medications (especially angiotensin- converting enzyme inhibitors, but also calcium channel blockers) and sun exposure damage has been hypothesized [1]. Dermoscopy examination can be helpful in assisting the diagnosis of ABCD by showing brownish structureless areas and linear vessels with reticular distribution histo- logically related to basal cell layer hyperpigmentation and dilated subpapillary vascular plexus visible through atro- phic epidermis. Such a dermoscopic pattern may come in handy to distinguish ABCD from its clinical mimickers, as they usually show different dermoscopic features, including 2 Image Letter | Dermatol Pract Concept. 2024;14(4):e2024275 extrafacial melasma, solar lentigos, macular amyloidosis, post- inflammatory hyperpigmentation, telangiectasia macu- laris eruptive perstans, poikiloderma of Civatte, essential progressive ascending telangiectasia, and poikilodermatous dermatomyositis [2]. References 1. Rongioletti F, Atzori L, Ferreli C. Acquired brachial cutaneous dyschromatosis. Clin Dermatol. 2021 Mar-Apr;39(2):199-201. DOI: 10.1016/j.clindermatol.2020.10.006. Epub 2020 Oct 16. PMID: 34272009. 2. Lallas A, Errichetti E, Ioannides D. Dermoscopy in General Dermatology. 1st ed. CRC Press. 2018. Figure 1. (A) Clinical examination shows several symmetrical light brown hyperpigmented and hypopigmented macules and telan- giectasia on both the forearms. (B) Dermoscopy reveals brownish unstructured areas and linear vessels with reticular distribution. (C) Minimal hyperkeratosis, slight epidermal atrophy and basal cell layer hyperpigmentation, dermal edema, and solar elastosis of the superficial dermis is evident on histology (H&E, ×40). (D) Detail of basal cell hyperpigmentation (H&E, ×150).