Renal tuberculosis (TB), an underrecognized form of extrapulmonary TB, often presents with nonspecific symptoms and challenging diagnosis and, therefore, it is difficult to diagnose. The subtle clinical manifestations and the absence of typical pulmonary signs frequently delay recognition and treatment. A 66-year-old man with type 2 diabetes mellitus and a cortical cyst in the left kidney presented to the emergency room with fatigue, anorexia, weight loss, and intermittent fever. Image exams revealed a large left renal cystic lesion initially suggestive of a cystic nephroma, which is a benign lesion. Ultrasound-guided aspiration and drainage of the lesion, followed by microbiological evaluation, identified co-infection with