Acute Myeloid Leukemia: FLT3/NPM1

Abstract

A 74-year-old male was found to have pancytopenia with low vitamin B12 levels on routine physical exam with his primary care physician. He complained of increasing fatigue over the last several months, which he attributed to his advancing age, but otherwise felt well. The patient denied any other symptoms. Pertinent family history revealed that his father died of acute leukemia at the age of 66 and his mother died at age 78 with heart complications and possible chronic lymphocytic leukemia. His primary care physician attempted to treat him with vitamin B12 in an effort to address the low levels, but there was no response. For additional assessment of his pancytopenia, the patient was referred to a hematologist who ordered laboratory studies to evaluate his peripheral blood and bone marrow. A complete blood count (CBC) showed megaloblastic anemia, a critically low white blood cell count, and thrombocytopenia. Upon review of the peripheral smear, the pathologist noted moderate anisopoikilocytosis of the red cells and rare circulating blasts. On aspirate smear, an increase in blasts was identified comprising approximately 30% of total nucleated cells. Erythroid precursors were markedly decreased. The core biopsy of the bone marrow correlated with these findings and showed decreased marrow cellularity of approximately 10%. A patchy interstitial increase in blasts was noted, comprising approximately 20% of total nucleated cells. Megakaryocytes were also decreased. Flow cytometric analysis on bone marrow revealed a distinct population of cells, comprising 20% of the total sample which expressed CD13, CD33 (low density), CD34, CD38, CD117, HLA-DR, and CD 45 (low density).