Breakthrough Candida guilliermondii (Meyerozyma guilliermondii) fungemia after cord blood transplantation for extranodal NK‐cell lymphoma with azole prophylaxis

: Fluconazole (FLCZ) is an azole antifungal agent and it has shown excellent clinical activities in suppressing fungemia with Candida albicans after hematopoietic stem cell transplantation. Increased administration of prophylactic FLCZ seems to have given rise to the relatively higher incidence of more resistant Candida non-albicans infection. We present a case with a rare breakthrough fungemia with C. guilliermondii after cord blood transplantation for Extranodal NK cell Lymphoma, nasal type (ENKL), during antifungal prophylaxis with FLCZ. High level of caution is needed for the breakthrough, especially after long-term azole administration.