[Mediastinal abscess due to Aspergillus in a patient with atypical chronic myeloid leukemia, BCR-ABL1-negative].

A 64-year-old male presented with a rapidly growing anterior mediastinal mass during the clinical course of atypical chronic myeloid leukemia. A needle biopsy performed for suspected myeloid sarcoma revealed the presence of Aspergillus abscess. Early diagnosis of mediastinal abscesses, which are associated with a high mortality rate, can prevent the progression of severity. Infectious abscesses should be considered for prompt qualitative diagnosis in patients with mediastinal masses. Thymoma, germ cell tumor, and malignant lymphoma are the most common anterior mediastinal tumors, whereas infectious abscesses should also be considered when myeloid sarcoma is suspected in patients with an underlying myeloid tumor.