Non-Inflammatory Nevus Comedonicus

Mauricio Salas-Garza¹ , Pablo Martínez-Fernández² , Julio Salas-Alanis³ , María G Moreno-Treviño¹ , Raúl Rubio-Moreno¹ , Augusto Salinas-Flores² , Gerardo Rivera-Silva^2*

¹Debra Foundation Mexico, Monterrey, NL, Mexico

²Academic Department, Faculty of Medicine, University of Monterrey, Monterrey, NL, Mexico

³Debra Foundation Mexico, Monterrey, NL, Mexico

⁴Department of Dermatology, PREPA No 15, Autonomous University of Nuevo Leon, Monterrey, NL, Mexico

*Correspondence author: Gerardo Rivera Silva, MD, PhD, 2Academic Department, Faculty of Medicine, University of Monterrey, Monterrey, NL, Mexico;
Email: gerardo.rivera@udem.edu

Citation: Salas-Garza M, et al. Non-Inflammatory Nevus Comedonicus. J Dermatol Res. 2026;7(2):1-2.

Copyright: © 2026 The Authors. Published by Athenaeum Scientific Publishers.

This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
License URL: https://creativecommons.org/licenses/by/4.0/

A 17-year-old male presented with a 12-year history of asymptomatic keratotic lesions involving the left anterior and posterior chest. According to the patient and his parents, the lesions first appeared at 5 years of age as a small cluster of dark follicular plugs over the left pectoral region and progressively extended in a unilateral linear pattern without pain, pruritus, discharge, recurrent infections or bleeding. The patient sought medical attention because of cosmetic concerns. His medical and family histories were unremarkable.

Dermatological examination revealed multiple grouped dilated follicular openings containing adherent black keratin plugs arranged in a unilateral segmental distribution over the left hemithorax (Fig. 1). The lesions respected the midline and followed the lines of Blaschko. Hair growth was preserved and the remainder of the examination was normal. Dermoscopy demonstrated enlarged follicular openings filled with homogeneous dark brown to black keratin plugs without vascular structures or inflammatory changes (Fig. 1), supporting the diagnosis of non-inflammatory nevus comedonicus. The patient was treated with topical adapalene 0.1% gel and emollients, resulting in partial reduction of keratin plugging after three months, although the distribution of the lesions remained unchanged.

Nevus comedonicus is a rare hamartomatous malformation of the pilosebaceous unit characterized by grouped keratin-filled dilated follicular ostia resembling open comedones. It usually develops at birth or during childhood, may follow the lines of Blaschko and has been associated with postzygotic NEK9 mutations, supporting a mosaic pathogenesis [1]. Dermoscopy is a useful non-invasive diagnostic tool, whereas histopathology typically demonstrates markedly dilated follicular infundibulum filled with laminated keratin and rudimentary hair structures [2]. The main differential diagnoses include acne comedones, porokeratotic eccrine ostial and dermal duct nevus, sebaceous nevus and inflammatory epidermal nevi. Treatment is mainly cosmetic and includes topical retinoids, keratolytics, systemic retinoids, laser therapy or surgical excision, although recurrence is common [2,3].

Keywords: Asymptomatic Keratotic Lesions; Dermoscopy; Non-Inflammatory Nevus Comedonicus

Figure 1: A, B: General appearance of the skin lesions; C: Dermoscopy (polarized mode, ×10) revealed enlarged follicular openings with dark brown to black keratin plugs, consistent with non-inflammatory nevus comedonicus.

Conflict of Interest

The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Funding Statement

This research did not receive any specific grant from funding agencies in the public, commercial or non-profit sectors.

Acknowledgement

The authors have no acknowledgments to declare.

Data Availability Statement

The data supporting the findings of this study are available from the corresponding author upon reasonable request.

Ethical Statement

The project did not meet the definition of human subject research under the preview of the IRB according to federal regulations and therefore was exempt.

Informed Consent Statement

Informed consent for publication was obtained from the patient involved in this study, as documented in the manuscript.

Authors’ Contributions

All authors have contributed equally to this work and have reviewed and approved the final manuscript for publication.

References

1. Torchia D. Nevus comedonicus syndrome: A systematic review of the literature. Pediatr Dermatol. 2021;38(2):359-63.
2. Albalawi OM, Alharthi MS, Alharbi AA, Alghamdi AA. Nevus comedonicus: A case report with the histological findings and brief review of the literature. Int J Surg Case Rep. 2023;105:108021.
3. Sadhukhan S. Dermoscopy of nevus comedonicus. J Cutan Med Surg. 2024;28(6):618.