A 41-year-old man with diabetes developed a serious lung infection caused by mucormycosis, a rare and dangerous fungus. Doctors diagnosed the infection using liquid-based cytology, a technique that examines fluid from the lungs under a microscope, which proved more effective than traditional methods. Treatment with antifungal medications helped stabilize the patient’s condition, and he remained healthy during an eight-month follow-up. This case highlights how advanced diagnostic techniques can help doctors quickly identify and treat severe fungal infections.