Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2022;12(2):e2022053 1 Childhood Flexural Comedones Li-wen Zhang1, MD, Juan Wu2, Lu Zheng1, Tao Chen1 1 Department of Dermatovenereology, Chengdu Second People’s Hospital, Chengdu, Sichuan, China 2 Sexually Transmitted Disease Institute, Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China Citation: Zhang L, Wu J, Zheng L, Chen T. Childhood flexural comedones. Dermatol Pract Concept. 2022;12(2):e2022053. DOI: https://doi.org/10.5826/dpc.1202a53 Accepted: August 14, 2021; Published: April 2022 Copyright: ©2022 Zhang 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: Tao Chen, Department of Dermatovenereology, Chengdu Second People’s Hospital, 165 Caoshi Street, Chengdu 610017, Sichuan, China. E-mail: 13980427003@163.com Case Presentation A 20-year-old female complained of an asymptomatic papule on the left postauricular skin that occurred shortly after birth. The lesion presented a single papule with double- orifice comedones (Figure 1A). At the same site, previous skin lesion or inflammation were not observed. The dermoscopy manifested double-ended pseudo-comedones (Figure 1B). Childhood flexural comedones (CFC) with late diagnosis in adulthood was established. Teaching Point CFC usually occur in the skin folds including axilla, neck, cubital fossa, and perineum, and present as double open- ing comedones connected by a thin layer of the epidermis. Figure 1. (A) A single papule with double-orifice comedones on the left postauricular skin. (B) The dermoscopy manifested double-ended pseudo-comedon. 2 Image Letter | Dermatol Pract Concept. 2022;12(2):e2022053 The etiology hypotheses included potential precursors of hidradenitis suppurativa, friction, genetic background, and hamartomatous origin [1]. Histopathology showed typical open comedo with follicular plugging and infundibular dila- tation [2]. Three different dermoscopic patterns of CFC have been described including cuneiform comedo, multi- orifice comedo, and double-ended pseudo-comedones [1]. The dif- ferential diagnosis includes other diseases associated with comedones, such as nevus comedonicus, acne neonatorum, familial dyskeratotic comedones, and idiopathic dissemi- nated comedones. References 1. Piccolo V, Russo T, Silva Pereira C, Darlington MD, Argenziano G. Dermoscopy of childhood flexural comedones: description of 4 cases. Int J Dermatol. 2018; 57(3):e21–e23. DOI: 10.1111/ ijd.13894. PMID: 29318614. 2. Larralde M, Abad ME, Munoz AS, Luna P. Childhood flexural comedones: a new entity. Arch Dermatol. 2007;143(7): 909–911. DOI: 10.1001/archderm.143.7.909. PMID: 17638736.