A 70-year-old man developed a serious lung condition caused by a fungal infection (Schizophyllum commune) that resulted in dangerous mucus buildup and asthma attacks despite standard treatments. When traditional medications failed, doctors tried a newer biologic drug called mepolizumab that targets immune cells causing inflammation. The treatment successfully cleared the mucus, improved breathing, and allowed the patient to stop taking steroid medications while remaining symptom-free for over two years.