1. Prepared by Abigayle Norwood and Reviewed by Sean Zhang MD PhD

An adult patient with a medical history of polycystic kidney disease status post kidney transplantation presented to the emergency department with cough, abdominal pain, and loose stools for approximately 2 weeks. Upon admission, they had a high fever (Tmax 102.6°F) and work up revealed pancytopenia and a positive Clostridioides difficile toxin B gene by nucleic acid testing. The patient's diarrhea improved with oral vancomycin. The cough was treated with loratadine.

The patient continued to spike intermittent fevers throughout their admission. They were started on broad-spectrum antimicrobials and a further infectious work up was initiated. Imaging studies revealed a lung nodule, hilar lymphadenopathy, and splenomegaly. Microbiology studies were significant for an elevated 1,3-beta-d-glucan and galactomannan. The fever ultimately improved and the patient was discharged on voriconazole with plans for outpatient follow-up of the lung nodule.

Two weeks later, a fungal culture of the patient's blood collected during hospitalization grew the filamentous organism pictured below. The microscopic features are most concerning for which of the following fungus?