Lomentospora prolificans is a rare filamentous fungus that causes invasive fungal disease (IFD) in immunocompromised patients with hematological malignancies, as well as hematopoietic cell or solid organ transplant recipients. A 75-year-old woman was diagnosed with acute myeloid leukemia, and started induction therapy with azacitidine and adjusted-dose venetoclax along with antifungal prophylaxis with fluconazole. On day 7, she became febrile and chest CT imaging showed multiple nodules in both lung fields, and the serum galactomannan antigen index became positive, indicating probable IFD. Anti-fungal therapy with liposomal amphotericin B was immediately initiated; however, the patient's condition rapidly deteriorated, and she died on day 15. L. prolificans was later identified in blood culture tests that had been repeatedly performed while she had been febrile. L. prolificans is generally resistant to most antifungal agents, which can make it fatal. As early definitive diagnosis is difficult, it may be appropriate to consider combination therapy when conventional anti-IFD therapy seems inadequate.
Keywords: Acute myeloid leukemia; Induction therapy; Invasive fungal disease; Lomentospora prolificans.