Dermatology: Practical and Conceptual Letter | Dermatol Pract Concept 2020;10(4):2020075 1 Dermatology Practical & Conceptual Introduction Pigmented purpuric lichenoid dermatitis of Gougerot and Blum is an uncommon variant of pigmented purpuric derma- tosis (PPD) characterized by confluent purpuric papules and plaques on the legs [1]. The overlap of the clinical features of the subtypes of PPD usually hinders its diagnosis. Case Presentation A 32-year-old black male, born in a West African coun- try, reported the development of multiple asymptomatic brown-to-violaceous plaques on the legs in the previous 2 months. He was diagnosed with human immunodeficiency virus (HIV) type 1 infection 9 years before but had bad com- pliance with highly active antiretroviral treatment (HAART). One month before noticing the development of skin lesions, HAART was reinitiated with emtricitabine, tenofovir and dolutegravir. At the time of presentation, CD4+ lymphocyte count was 870 cells/mm3 and viral load was 22 copies/mL. Se- rologies for syphilis and hepatitis B and C virus were negative. On skin examination, the patient had multiple red-brown nummular plaques with an oval-to-irregular outline on the legs (Figure 1). The lesions measured 1 to 3 cm in diameter, had a lighter central area, and were surrounded by a narrow erythematous-violaceous border. Dermoscopy revealed a diffuse coppery-red structureless background permeated by a brownish-to-gray network with ill-defined borders and a polymorphic pearly white central area with polygonal-to-oval red and gray dots, globules, and patches (Figure 2). Histopathologic examination revealed a dense band-like lymphocytic infiltrate in the upper dermis, endothelial cell swelling and extravasation of red blood cells with hemosid- erin inside of macrophages. There was no visible vessel wall damage (Figure 3). Dermoscopy of Pigmented Purpuric Lichenoid Dermatitis of Gougerot and Blum in an HIV-infected Patient Pedro Miguel Garrido1, Pablo Espinosa-Lara1, Marta Aguado-Lobo1, Luís Soares-Almeida1,2,3, João Borges-Costa1,2,3,4 1 Dermatology Department, Centro Hospitalar Universitário Lisboa Norte, EPE (CHULN), Lisbon, Portugal 2 Dermatology University Clinic, Faculty of Medicine, University of Lisbon, Portugal 3 Dermatology Research Unit, Instituto de Medicina Molecular, University of Lisbon, Portugal 4 Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa, Lisbon, Portugal Key words: dermoscopy, pigmented purpuric dermatosis, pigmented purpuric lichenoid dermatitis of Gougerot and Blum, human immunodeficiency virus Citation: Garrido PM, Espinosa-Lara P, Aguado-Lobo M, Soares-Almeida L, Borges-Costa J. Dermoscopy of pigmented purpuric lichenoid dermatitis of Gougerot and Blum in an HIV-infected patient. Dermatol Pract Concept. 2020;10(4):e2020075. DOI: https://doi.org/10.5826/dpc.1004a75 Accepted: April 21, 2020; Published: October 26, 2020 Copyright: ©2020 Garrido et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License BY-NC-4.0, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: None. Competing interests: The authors have no conflicts of interest to disclose. Authorship: All authors have contributed significantly to this publication. Corresponding author: Pedro Miguel Garrido, MD, Centro Hospitalar Lisboa Norte EPE, Av. Prof. Egas Moniz, Lisboa 1649-035, Portugal. Email: pedro.mi.garrido@gmail.com 2 Letter | Dermatol Pract Concept 2020;10(4):2020075 Figure 1. Clinical findings: red-brown nummular plaques with a lighter central area surrounded by a narrow erythematous-vio- laceous border on the legs. Figure 2. Dermoscopic findings: diffuse coppery-red structureless background (black star) permeated by a brownish-to-gray network with ill-defined borders and a polymorphic pearly white central area (red star) with polygonal-to-oval red and gray dots (blue and yellow star, respectively), red globules (green arrow) and patches. Figure 3. Histopathologic findings. (A) Dense band-like lympho- cytic infiltrate in the upper dermis and increased number of dilated blood vessels. (B) Endothelial cell swelling and extravasation of red blood cells with hemosiderin inside of macrophages. (C) Hemosid- erin deposition in the upper dermis. (A,B) H&E stain; original mag- nifications ×40, ×100. (C) Perls Prussian blue iron stain; original magnification ×40). A B C Letter | Dermatol Pract Concept 2020;10(4):2020075 3 hypertension, diabetes mellitus, and autoimmune diseases [1]. Although the etiology of PPD remains unknown, previ- ous reports suport a role for cell-mediated immunity on its pathogenesis [1]. In this case, skin lesions developed after initiation of HAART, alongside viral suppression and immu- nity improvement. Pigmented purpuric lichenoid dermatitis of Gougerot and Blum may therefore be a consequence of the immunity imbalance associated with the immune recon- stitution inflammatory syndrome. References 1. Kim DH, Seo SH, Ahn HH, Kye YC, Choi JE. Characteris- tics and clinical manifestations of pigmented purpuric der- matosis. Ann Dermatol. 2015;27(4):404–410. DOI: 10.5021/ ad.2015.27.4.404. PMID: 26273156. 2. Park MY, Shim WH, Kim JM, et al. Dermoscopic finding in pig- mented purpuric lichenoid dermatosis of Gougerot-Blum: a use- ful tool for clinical diagnosis. Ann Dermatol. 2018;30(2):245– 247. DOI: 10.5021/ad.2018.30.2.245. PMID: 29606831. Conclusions The clinical diagnosis of pigmented purpuric lichenoid der- matitis of Gougerot and Blum is challenging, as this derma- tosis can closely resemble Kaposi sarcoma—an important differential diagnosis in HIV patients like ours—cutaneous vasculitis, and other PPDs, particularly lichen aureus. Der- moscopy is a noninvasive technique that may increase ac- curacy in the differential diagnosis. One previous report de- scribed its dermoscopic findings [2]. In comparison, our case stands out because of the coppery-red structureless back- ground and the pearly white central area. The differences in the clinical presentation and dermoscopic findings correlate with the variability in histopathologic features: the presence of a coppery-red structureless background results from the lichenoid infiltrate and the extravasation of red blood cells with hemosiderin deposition in macrophages; the pearly white central area is explained by the increased number of hemosiderin-laden macrophages on the dermis. PPD has been associated with many conditions, such as