DOI: https://doi.org/10.36347/sjmcr.2026.v14i09.027

Pages: 2071-2074

Introduction: Extramedullary plasmacytomas (EMP) correspond to plasma cell tumor localizations outside the bone marrow. They can present as a localized solitary form or as a manifestation of systemic multiple myeloma [1]. Their mediastinal location remains exceptional [2]. Diagnosis is often challenging, particularly when conventional biological markers of multiple myeloma are absent. For localized forms, radiotherapy constitutes the reference therapeutic option [3]. We present a case of EMP developing in the anterior mediastinum and propose, through a literature analysis, a reflection on management strategies in radiation oncology. Case Report: A 32-year-old female patient, with no notable medical history, consulted for progressive onset of dry cough and dyspnea. Chest imaging revealed a large anterior mediastinal mass measuring 12.4 cm with displacement of mediastinal structures. Histological examination of CT-guided biopsy revealed morphological and immunohistochemical features consistent with a plasma cell neoplasm. Laboratory tests showed 2% plasma cells on bone marrow aspirate. The diagnosis of solitary mediastinal extramedullary plasmacytoma was retained. The patient was referred to a medical oncology department for discussion of therapeutic options. Conclusion: Radiotherapy plays a predominant role in the treatment of solitary EMP, with excellent local control rates [4]. Nevertheless, the distinction between solitary EMP and EMP associated with systemic multiple myeloma is fundamental, as it guides management toward radically different approaches [5]. Serum free light chain assay is an essential diagnostic tool, particularly when serum protein electrophoresis shows no abnormality [6].