A Case Report of the Atypical Presentation of Multiple Myeloma Manifesting as a Sternal Mass

The diagnosis of multiple myeloma (MM) is made based on the presence of either marrow clonal plasma cells > 10% or an extramedullary or bony plasmacytoma confirmed by biopsy. Additionally, at least one of the SLiM (sixty years, light chain ratio, magnetic resonance imaging)-CRAB (calcium elevation, renal insufficiency, anemia, and bone lesions) myeloma-defining events must be present. MM typically presents with symptoms such as fatigue due to anemia, kidney failure, hypercalcemia, and bone pain. It is uncommon, though, for MM to manifest as a single bone mass. We report the case of a 65-year-old male who did not fit the criteria for solitary bone plasmacytoma and presented with an unusual sternal tumor. The patient was diagnosed with MM despite not having any of the traditional symptoms such as low back pain, weight loss, anemia, or hypercalcemia. The diagnosis was based on a bone marrow examination, which showed 50% plasma cells. Radiation therapy and systemic chemotherapy were then used to treat him. The patient's symptoms, radiological findings, and biopsy results are described in detail, emphasizing the difficulty and intricacy of correctly diagnosing this uncommon manifestation of MM. This case highlights the need for a comprehensive and multidisciplinary strategy to diagnose and treat atypical presentations of MM, making sure that all possible diagnostic pathways are investigated in order to achieve accurate and timely diagnosis and treatment.