Dermatology: Practical and Conceptual Dermatology Practical & Conceptual Letter | Dermatol Pract Concept. 2021; 11(3): e2021053. 1 Unilateral Linear Capillaritis Dermoscopic Examination: A Distinct Clinico-Histopathological Correlation Jayanti Singh1, Priyadarshini Sahu1, Surabhi Dayal1, Sant Prakash Kataria2 1 Department of Dermatology, Venereology and Leprology, Pt B D Sharma University of Health Sciences, Rohtak, Haryana, India 2 Department of Pathology, Pt B D Sharma University of Health Sciences, Rohtak, Haryana, India Running title: Unilateral Linear Capillaritis Dermoscopy Key words: Unilateral Linear Capillaritis, Dermoscopy, pigmented purpuric dermatosis Citation: Singh J, Sahu P, Dayal S, Kataria SP. Dermoscopy of Unilateral Linear Capillaritis: A Distinct Clinico-Histopathological Correlation. Dermatol Pract Concept. 2021; 11(3): e2021053. DOI: https://doi.org/10.5826/dpc.1103a53 Accepted: December 7, 2020; Published: July 8, 2021 Copyright: ©2021 Singh 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 authors and source are credited Funding: None Competing interests: None Authorship: All authors have contributed significantly to this publication Corresponding author: Surabhi Dayal, Senior Professor and Head of the Department (M.D), Department of Dermatology, Venereology and Leprology, Pt B D Sharma University of Health Sciences, Rohtak, Haryana, India. Email: surabhidayal7@gmail.com Introduction Unilateral linear capillaritis (ULC) is a rare variant of pig- mented purpuric dermatosis (PPD). It is characterized by unilateral, progressive, linear eruption of purpuric patches or macules. It is a benign condition and often resolves spon- taneously. To the best of our knowledge, ULC dermoscopic features have only been described in 1 case report. Herein, we attempted to compare the dermoscopic features of ULC with PPD and differentiate it from linear pityriasis rosea (PR). In the present case, we also found a few more dermoscopic features characterizing ULC, which have not been reported yet in the literature. To establish ULC dermoscopic features and differentiate it from other linear dermatoses, there is the need to present additional findings to enrich the current documentation. Case Report A 32-year-old male presented with mildly itchy erythematous rash covering the left side of the chest, arm and forearm. The rash was ongoing in the last 3-4 months. On cutaneous examination, there were multiple erythematous, slightly scaly round-to-oval patches, varying from 0.5-5 cm in size, associ- ated with coppery tinge, seen on the anterior part of left chest (not crossing the midline), flexor aspect of left upper limb and left palm (Figure 1). Other cutaneous and systemic examina- tions were normal. Routine investigations were within normal 2 Letter | Dermatol Pract Concept. 2021; 11(3): e2021053. ranges. Differential diagnosis of ULC and linear PR were considered. Dermoscopy was performed using DermLite IV at 10x magnification, and revealed coppery-red background, lin- ear white and red lines, red globules, red and brown dots, and scaling (Figure 2). On histopathological examination, the epi- Figure 1. Multiple linear erythematous, slightly scaly, patches seen on the anterior side of the left chest, flexor aspect of left upper limb and palm. Figure 2. Dermoscopy showing red globules (black arrow), red (red arrow) and brown dots (blue circle), scaling (blue arrow), linear white (green arrow) and red lines (blue circle) with coppery-red background (DermLite DL4, ×10, Polarized light). dermis appeared mildly atrophic with loss of dermal papillae and the basal layer showed focal vacuolization (Figure 3). Der- mis revealed edema, dense perivascular lymphocytic infiltrate, and extravasation of red blood cells (RBC). Based on these findings, diagnosis of ULC was made. The patient was treated conservatively, and he recovered within 2 weeks. Discussion Dermoscopy can be used for differentiating ULC from linear PR. On dermoscopy of PPD, coppery-red background due to lymphohistiocytic dermal infiltration, extravasated RBCs, and hemosiderin deposition is observed. Red dots and glob- ules represent extravasated RBCs and dilated blood vessels. Brown dots represent melanocytes in basal layer of epidermis and dermal melanophages in upper dermis. Scaling observed in our patient, might be due to the chronicity of the lesions. In PR, peripheral white scales and few red dots are seen in yellowish background [1]. Based on the clinical and dermoscopic findings we con- cluded that dermoscopic features of ULC are similar to the ones reported in PPD. In our case, scaling was an additional finding. Recently, a case report described dermoscopy of ULC. The authors observed dermoscopic features such as linear vessels, brown reticular lines, red dots, and clods with a brown-pigmented network [2]. In addition to these features, we also observed brown dots and linear white lines along dermatoglyphics secondary to scaling. To best of the authors’ knowledge, the dermoscopic features such as brown dots and scaling in ULC have not been reported in the literature yet. Thus, our findings could further help dermatologists in the diagnosis of ULC and differentiating it from linear PR, which Letter | Dermatol Pract Concept. 2021; 11(3): e2021053. 3 might preclude the need for invasive procedures such as skin biopsy for a benign and self-resolving condition. References: 1. Lallas, A. Kyrgidis, TG Tzellos et al. Accuracy of dermoscopic criteria for the diagnosis of psoriasis, dermatitis, lichen planus and pityriasis rosea. Br J Dermatol. 2012;166(6):1198-205. DOI: 10.1111/j.1365-2133.2012.10868.x. PMID: 22296226. 2. Kumar P, Desai C, Das A. Unilateral linear capillaritis. Indian Der- matol Online J [Epub ahead of print] [cited 2020 Oct 29]. Avail- able from: https://www.idoj.in/preprintarticle.asp?id=295477. DOI. 10.4103/idoj.IDOJ_649_19. Figure 3. Histopathological analysis showed mildly atrophic epider- mis with basal layer displaying focal vacuolization and dense peri- vascular lymphocytic infiltrate in the dermis.