A 12-month-old girl with a severe immune system disorder (HLH) triggered by Epstein-Barr virus developed a life-threatening fungal infection (mucormycosis) that spread throughout her digestive system. Despite aggressive treatment with multiple antifungal medications and emergency surgery, the infection caused her intestines to perforate, leading to her death. The case highlights the difficulty in recognizing fungal infections early in immunocompromised children and the need for heightened clinical awareness.