This case illustrates the diagnostic and therapeutic challenges posed by MRSA-positive sternoclavicular septic arthritis, especially when presenting with atypical features that mimic malignancy. Successful management required a multifaceted approach, including advanced imaging, precise diagnostics, embolization, and prolonged antibiotic therapy. The case underscores the critical need for thorough evaluation in atypical infections to differentiate from malignancies, highlighting the importance of tailored treatment strategies and interdisciplinary collaboration in achieving favorable outcomes. This unique presentation enriches medical literature and offers valuable insights into the complexity of diagnosing and treating rare infections in patients with multiple comorbidities.