Decoding Pyrexia of Unknown Origin (PUO)! A patient with fever for >3 weeks, multiple negative investigations, and failed antibiotic courses. It's a classic PUO case. 🧩 The Golden Dictum: "PUO is more likely a Common Disease presenting Atypically, rather than a Rare Disease presenting Typically." 🔍 The Big 4 Categories to Investigate: Infections: Still the #1 cause (TB, Endocarditis, Abscesses). Note: As duration increases, likelihood of infection decreases. Malignancy: Lymphomas, Leukemia, RC