First Reported Coexistence of Plasma Cell Gingivitis and Multiple Sclerosis: A Case Report.

Background: Plasma cell gingivitis (PCG) is a rare, benign inflammatory condition of the oral mucosa characterized histologically by a dense plasmacytic infiltrate. Its etiology remains uncertain, with proposed triggers including allergens, infectious agents, and idiopathic immune reactions. Multiple sclerosis (MS), on the other hand, is a chronic autoimmune demyelinating disorder of the central nervous system that may indirectly influence oral health due to neurological impairment, altered immunity, or long-term medication use. However, the coexistence of PCG and MS is extremely rare, and to the best of our knowledge, no such association has been previously documented in the literature. This report describes a unique case of PCG occurring in a patient with long-standing, well-controlled MS. Case Presentation: A 26-year-old woman with a 9-year history of clinically stable and well-controlled MS presented with complaints of gingival pain and spontaneous bleeding. Clinical examination revealed diffuse erythematous and edematous gingiva involving both anterior and posterior segments. Routine hematologic and biochemical investigations were unremarkable. An incisional biopsy of the affected gingiva was performed, and histopathological analysis demonstrated a dense, polyclonal plasma cell infiltrate consistent with PCG. Based on these findings, a diagnosis of PCG was established. The patient was initiated on a corticosteroid mouthwash regimen, resulting in symptomatic improvement. No systemic manifestations or MS exacerbations were noted during the course of dental evaluation and treatment. The patient was followed for 6mounths after initiating corticosteroid mouthwash. During this period, she demonstrated significant improvement of gingival erythema, with evidence of relapse. Her MS also remained clinically stable throughout the follow-up. Conclusion: This case highlights the unusual coexistence of PCG and MS-an association that, to the best of our knowledge, has not previously been reported. While the relationship between the two conditions remains unclear, this observation raises the possibility of shared immunologic pathways or coincidental occurrence. Further studies are needed to explore potential connections and to guide clinicians in managing similar presentations.