Facial Annular Lesions in a 28‐Year‐Old Man

A 28-year-old Dominican male, with no significant medical history, presented a 60-day history of asymptomatic facial lesions. These lesions, characterized by annular configurations, progressively increased in size and number. The patient denied any genital or lesions elsewhere on the body. Physical examination revealed multiple skin-colored papules, 3–5 mm in diameter, located on the midline of the forehead, bilateral cheeks, and anterior cervical region. Most of these papules were coalescent, forming various annular, spiral, or linear structures, all with a hyperpigmented base (Figures 1 and 2). Dermatoscopy showed no specific findings. No other lesions were observed on the rest of the body or mucous membranes. When questioned specifically, the patient denied previous infectious episodes, recent use of new medications or vaccines, or family members with similar symptoms. A blood test was performed to assess possible causes of facial annular lesions. At the same time, it was decided to perform empirical treatment as a diagnostic test. When questioned directly, he reported unprotected high-risk sexual activity more than 6 months prior, without noting genital lesions at that time. Screening for sexually transmitted infections (STIs) revealed a negative HIV ELISA and a Treponema pallidum serology (Venereal Disease Research Laboratory “VDRL”) titer of 1:128, with a positive MHA-TP (Microhemagglutination Treponema pallidum). Based on these findings, treatment with benzathine penicillin 2.4 M weekly for two doses was initiated. After treatment, the patient exhibited marked improvement of the lesions within 1-week posttreatment, with a noticeable reduction in the thickness of the lesions described, with persistent post-inflammatory hyperpigmentation during subsequent follow-up visits, and without any new recurrences. Syphilis is a chronic sexually transmitted infection, caused by Treponema pallidum, characterized by a diverse range of clinical manifestations, potentially involving multiple organs [1]. This disease progresses through stages of infectious activity, including primary, secondary, and tertiary syphilis, alternating with periods of latency [2]. Secondary syphilis represents the expression of hematogenous dissemination of the microorganism, with mucocutaneous lesions being the most common manifestation, typically presenting as a diffuse maculopapular exanthem on the trunk and extremities, frequently associated with palmoplantar involvement [3]. However, a broad spectrum of atypical cutaneous lesions can manifest in this infection, leading to its characterization as “the great imitator,” with presentations including nodular, annular, pustular, pyodermatous, photodistributed papulosquamous lesions, among others [4]. Annular secondary syphilis, as observed in our patient (Figures 1 and 2), is infrequent, with a prevalence between 5.7% and 13.6%, occurring mostly in children and patients with high phototypes [5, 6]. Within annular lesions, there are different variations that pose a greater diagnostic challenge, even being observed in congenital syphilis [6]. The reason for the great polymorphism of cutaneous lesions as a clinical expression of this infection is still unclear; however, it is thought that pro-inflammatory factors in the dermis, as well as in deeper vascular structures, are involved, generating processes of cutaneous ischemia [7]. These annular lesions are described from round or oval, slightly scaly papules to verrucous exophytic forms, which can be distributed in complete or incomplete rings, forming polycyclic, concentric or even gyrata-like patterns [8, 9]. These patterns can affect the scalp, perioral area, trunk, and perianal and genital regions, the latter being described as rare, however, there has been an increasing frequency observed [9, 10]. Considering the characteristics of these lesions, it is necessary to make a differential diagnosis with other annular lesions, such as granuloma annulare, annular lichen planus, annular psoriasis, scabies, or dermatophytosis [4]. This case is distinctive due to the number of facial lesions, which were abundant and well-defined, both uncommon phenotypic characteristics in these patients. Therefore, it is important to consider secondary syphilis as part of the differential diagnosis of facial annular lesions, to have adequate study and the correct treatment, considering the effective and rapid response to the use of antibiotics. Maximiliano Maass, Paula Giacaman, and Ester Santander conceptualized the case report and contributed to its design. Maximiliano Maass collected the clinical data, including patient history, dermatological findings, and pictures. Maximiliano Maass and Angelo González drafted the initial manuscript. Maximiliano Maass and Angelo González reviewed and revised the content for accuracy, clarity and ensured its scientific integrity. All authors have reviewed and approved the final version of the manuscript for submission and agree to be accountable for all aspects of the work. This study did not receive any specific grant from funding agencies in the public, commercial, or non-profit sectors. The patient in this manuscript has given written informed consent for participation in the study and the use of their deidentified, anonymized, aggregated data and their case details (including photographs) for publication. The authors declare no conflicts of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.