Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2025;15(1):5046 1 Keratosis Lichenoides Chronica Successfully Treated with Doxycycline: A Therapeutic Option for a Rare Dermatologic Condition Paula Dall’Oglio Furlan1, Martín Vásquez Zuloaga1, Cristhian Muñoz1, Danielle Quintella1, Tullia Cuzzi1, Marcus Trovó1 1 Institute of Dermatology Professor Rubem David Azulay, PUC - Rio, Brazil Citation: Dall’Oglio Furlan P, Vásquez Zuloaga M, Muñoz C, Quintella D, Cuzzi T, Trovó M. Keratosis Lichenoides Chronica Successfully Treated With Doxycycline: A Therapeutic Option for a Rare Dermatologic Condition. Dermatol Pract Concept. 2025;15(1):5046. DOI: https://doi.org/10.5826/dpc.1501a5046 Accepted: April 30, 2024; Published: July 2024 Copyright: © Dall’Oglio Furlan 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: Martín Vásquez Zuloaga. Address: Rua Santa Luzia 206 Centro, Rio de Janeiro, Brasil. CEP 20020-022. E-mail: martinalfonsovz@gmail.com Case Presentation A 29-year-old woman with no medical or family history presented with an 11-year history of skin lesions. Physical examination revealed linearly distributed plaques with a verrucous crusted lichenified surface on the extensor and flexor areas of the forearms and lower limbs (Figure 1A). The patient reported scaling and bleeding erosions on her lips. Blood tests were normal. A skin biopsy was conducted, revealing hyperkeratosis accompanied by parakeratosis, irregular acanthosis, focal hyper-granulosis, and vacuolar degeneration of the basal layer. Additionally, a dermal in- flammatory infiltrate nearly obscured the dermo-epidermal junction (Figure 1B). Based on the clinical presentation and histopathologic findings, the diagnosis of keratosis lichenoi- des chronica was established. She underwent phototherapy 3 times a week for 1 year without improvement. Subse- quently, she received doxycycline 100 mg twice daily for 3 months, resulting in significant improvement, character- ized by thinning of the previous skin lesions and absence of new lesions (Figure 1C). Teaching Point Keratosis lichenoides chronica, also known as Nekam dis- ease, is a rare acquired chronic dermatosis typically affecting young individuals between 20 and 50 years of age, involv- ing the skin and mucous membranes [1]. One of the distinc- tive features and significant challenges of this disease is its resistance to available treatments. Evidence is limited but suggests that phototherapy and systemic retinoids (mostly acitretin), either alone or in combination, are the most ef- fective treatments [2]. Systemic antibiotics have shown little to no consistent improvement; therefore, we present a case demonstrating a favorable response in order to consider it as a therapeutic option for this rare entity. 2 Image Letter | Dermatol Pract Concept. 2025;15(1):5046 References 1. Martins LC, Horne M, Moreira Júnior DN, Follador I, Almeida VR. Keratosis lichenoides chronica--case report. An Bras Dermatol. 2011 Jul-Aug;86(4 Suppl 1):S148-S151. DOI: 10.1590 /s0365-05962011000700039. PMID: 22068797. Figure 1. (A) Pre-treatment: Hyperkeratotic brown-violet plaques with mild scaling ob- served in the antecubital region. Additionally, hematic erythematous-violet crusted plaques were noted on the lips. (B) Histopathology: Hyperkeratosis with parakeratosis, irregular acanthosis, focal hyper-granulosis, and vacuolar alteration of the basal layer. The inflam- matory infiltrate in the upper dermis comprised lymphocytes, macrophages, and a few neu- trophils (H&E, ×10). (C) Post-treatment: Hyper-pigmented macules and plaques present on prior lesions accompanied by residual scaling. Notably, the lesions on the lips have resolved. 2. Pistoni F, Peroni A, Colato C, Schena D, Girolomoni G. Keratosis lichenoides chronica: Case-based review of treatment options.  J Dermatolog Treat. 2016;27(4):383-388. DOI:10.3109/095466 34.2015.1115818. PMID: 26652284.