Invasive fungal infections (IFIs) are among the most severe complications in recipients of hematopoietic stem cell transplantation (HSCT) recipients and in patients with hematological malignancies. An increasing number of uncommon fungal infections have been reported in this era of antifungal prophylaxis. Coprinopsis cinerea is a rare pathogen that causes opportunistic infections in the immunocompromised patients, including HSCT recipients and is associated with very high mortality rates. Herein, we present a successfully treated pediatric HSCT patient with breakthrough pulmonary IFI caused by Coprinopsis cinerea despite posaconazole, prophylaxis using multidisciplinary approaches.