Plasma Cell Gingivitis: Clinical Presentation, Histopathologic Correlation, and Therapeutic Challenges.

Background/Objectives: Plasma cell gingivitis (PCG) is a rare, benign, non-dental-plaque-induced inflammatory condition characterized by dense subepithelial infiltration of polyclonal plasma cells. Due to its nonspecific clinical presentation, PCG represents a diagnostic challenge. This case report aims to describe a clinical case of PCG, highlighting the diagnostic process, histopathological correlation, and therapeutic approach. Methods: A 57-year-old male presented with a polypoid, erythematous, and edematous gingival lesion in the anterior maxillary region, with spontaneous bleeding on probing. Following clinic assessment, an incisional biopsy was performed, alongside complete hematological and inflammatory profiling. Histological and immunohistochemical analyses revealed the presence of an inflammatory infiltrate. Results: Histological evaluation revealed spongiotic squamous epithelium characterized by a dense plasma cell infiltrate with a liquenoid pattern of CD3-positive T and CD20-positive B lymphocytes. A polytypic expression of kappa and lambda light chains was also detected. The patient underwent topical corticosteroid therapy, showing progressive clinical improvement and resolution of symptoms, although minor mucosal involvement persisted. Conclusions: PCG remains a rare and underdiagnosed condition requiring integration of clinical, hematological, and histopathological data for accurate diagnosis. While corticosteroids remain the first-line therapy, emerging treatments, including photobiomodulation, may offer future adjunctive strategies to improve outcomes and reduce recurrence.