USMLE® Step 1 style questions USMLE
A 51-year-old woman comes to the office because of new fatigue and shortness of breath for a month. She has a history of breast cancer which was successfully treated with surgery, chemotherapy, and radiotherapy. Complete blood count shows a pancytopenia (decreased RBCs, WBCs, and platelets). A bone marrow biopsy shows hypercellular marrow. Which of the following is the most likely diagnosis?