Supplementary Material for: Extramedullary Plasmacytoma of the Base of Tongue: A Case Report

Introduction:
Extramedullary plasmacytoma (EMP) is a rare plasma cell neoplasm typically arising outside the bone marrow. EMP involving the base of the tongue is particularly uncommon, posing diagnostic and therapeutic challenges due to its rarity and nonspecific presentation.
Case Presentation:
A 65-year-old male presented with progressive dysphagia, odynophagia, and significant weight loss. Biopsy of a tongue-base mass initially suggested a high-grade hematolymphoid neoplasm, subsequently confirmed as EMP on secondary pathology review. Positron emission tomography–computed tomography (PET/CT) imaging revealed localized fluorodeoxyglucose (FDG)-avid involvement of the tongue base and bilateral cervical lymph nodes. Bone marrow biopsy was negative for systemic disease. The patient was treated with definitive radiation therapy, resulting in complete clinical and radiologic resolution of disease on follow-up PET/CT three months post-treatment. Surveillance studies showed no progression to multiple myeloma.
Conclusion:
Clinicians should maintain a high index of suspicion for EMP in patients presenting with persistent oropharyngeal symptoms and atypical masses. Early recognition and definitive radiation therapy can lead to excellent outcomes and prevent progression to systemic disease.