Acute Necrotizing Ulcerative Gingivitis Associated With Actinomyces Infection in an Immunocompetent Adolescent

Persistent ulcerative lesions of the oral mucosa are diagnostically challenging, particularly in otherwise immunocompetent adolescents. The differential diagnosis is broad, ranging from infectious and autoimmune conditions to paraneoplastic conditions. A 16-year-old male presented to our office with painful oral ulcers that developed 4 days after placement of lower dental braces. Initially attributed to mechanical trauma, the lesions rapidly worsened over the following week, involving the lateral tongue, gingiva, buccal mucosa, and hard palate (Figure 1), causing severe odynophagia that precluded oral intake. He was subsequently admitted to the hospital for pain management and nutritional support. Physical examination revealed multiple deep ulcerations with fibrinous bases and hemorrhagic crusting of the oral mucosa, without cutaneous or genital involvement. Bilateral cervical lymphadenopathy was present, but no other systemic symptoms were noted. Laboratory evaluation showed normal inflammatory markers. Herpes simplex virus (HSV) serology was positive for both immunoglobulin M (IgM) and immunoglobulin G (IgG), but repeated polymerase chain reactions (PCRs) for HSV-1 and HSV-2 from oral lesions were negative. Serologic testing for other viral pathogens and Mycoplasma pneumoniae was also negative. Removal of the dental braces did not result in clinical improvement. Despite multiple empirical therapies, including topical mouthwashes, antiviral agents, systemic corticosteroids, and colchicine, the patient's condition continued to deteriorate, with clinical resolution delayed for nearly 1 month until the definitive diagnosis was established. A biopsy with direct immunofluorescence revealed a linear deposition of C3 along the basement membrane. Given extensive necrotic lesions and poor oral hygiene secondary to pain, bacterial superinfection was suspected, raising consideration for a diagnosis of acute necrotizing ulcerative gingivitis (ANUG). Empirical antibiotic therapy with amoxicillin–clavulanic acid led to rapid and marked clinical improvement (Figure 2), with complete re-epithelialization of all lesions within 1 week. Histopathological examination demonstrated necrotizing inflammation with a dense polymorphous infiltrate and bacterial colonies consistent with Actinomyces spp. At follow-up, the patient remained asymptomatic 6 months later. ANUG is a rapidly progressive periodontal infection resulting from a synergistic interaction between pathogenic anaerobes and impaired host defenses [1, 2]. Although classically associated with malnutrition or human immunodeficiency virus (HIV), ANUG may also occur in immunocompetent individuals, under conditions of severe stress, tobacco use, or, as seen in our patient, mechanical triggers and secondary poor oral hygiene [2-4]. The clinical hallmarks of ANUG include ‘punched-out’ interdental papillae and a characteristic fetid odor [1]. Although the bacterial culture is not diagnostic, the disease is characterized by a polymicrobial infection dominated by Fusobacterium spp. and spirochetes, leading to epithelial necrosis and dense neutrophilic infiltration [3, 4]. Without appropriate treatment, lesions may extend to involve deeper periodontal tissues, resulting in necrotizing periodontitis and attachment loss [5]. Management primarily consists of gentle debridement and improvement of oral hygiene, including the use of antiseptic rinses such as chlorhexidine. Systemic antibiotic therapy is reserved for patients with severe disease, systemic symptoms, or immunosuppression [5]. Addressing behavioral and psychosocial factors, particularly smoking cessation and stress reduction, is essential for preventing recurrence. Although the incidence of ANUG has declined in developed settings, it should remain part of the differential diagnosis of oral ulcers in patients with recent trauma and secondary poor oral hygiene complicated by infection. In our case, we hypothesize that poor oral hygiene, secondary to pain caused by recent dental braces, favored the development of ANUG. Although this represents an exceptional presentation, we emphasize the importance of maintaining a broad differential diagnosis when evaluating necrotic oral lesions, including consideration of ANUG even in otherwise healthy adolescents, and of re-evaluating initial diagnoses when standard treatments fail. The authors have nothing to report. The patients in this manuscript have given written informed consent to the publication of their case details. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request. Please contact A.Aramburu Gonzalez at [email protected].