Extramedullary plasmacytoma of the Gingiva: A rare case report and clinical management.

Extramedullary plasmacytoma (EMP) of the gingiva is an exceptionally rare plasma cell neoplasm, posing significant diagnostic challenges due to its nonspecific clinical presentation and low incidence. This case report details a 67-year-old male presenting with a painless right maxillary gingival mass, initially mimicking benign hyperplasia. Diagnostic workup, including cone-beam computed tomography (CBCT), revealed osteolytic bone destruction and soft tissue expansion. Histopathological and immunohistochemical (IHC) analyses confirmed monoclonal plasma cell proliferation (CD38+, CD79a+, MUM-1+, κ-light chain restriction) with a markedly elevated Ki-67 index (80 %). Radical surgical resection achieved R0 margins, and adjuvant radiotherapy was deferred based on complete excision. The case highlights critical diagnostic considerations: EMP necessitates differentiation from chronic gingivitis, B-cell lymphomas, and head/neck malignancies, with immunohistochemistry (CD138, κ/λ restriction) and PET-CT serving as pivotal tools. The observed Ki-67 elevation aligns with evidence suggesting higher proliferative activity in EMP compared to solitary bone plasmacytomas, emphasizing the role of risk-adapted adjuvant therapy for tumors with Ki-67 > 50 %. Furthermore, κ-light chain predominance (>90 %) underscores clonal proliferation dynamics, while longitudinal surveillance for systemic progression to multiple myeloma remains imperative. This report advocates for early biopsy of atypical oral lesions, multidisciplinary collaboration, and lifelong monitoring to mitigate diagnostic delays and optimize outcomes. It underscores the importance of integrating molecular profiling (e.g., 1q21/MYC status) into prognostic models for this rare entity, ultimately guiding precision management strategies.