Hypocellular acute myeloid leukemia: the Rochester (New York) experience

Fourteen patients with hypocellular acute leukemia (HAL) were reviewed. The median age was 72 years, with an equal male-to-female ratio. Severe granulocytopenia with marrow hypocellularity and increased marrow blasts and absence of physical findings were common features. The median peripheral blood blast count was 2%. All except 3 cases of erythroleukemia had marrow blast count that exceeded 30% of all nucleated marrow cells. All cases were classifiable with the FAB criteria. FAB classification revealed a preponderance of the M1 category followed by M2 and M6 types. The majority of blasts were type I and the median myeloperoxidase positivity was 14%. Immunophenotyping of bone marrow cells by flow cytometry in 9 cases showed expression of myeloid antigens (CD13, CD33); 6 cases also expressed CD34 antigen. Significant dysplasia involving erythroid and megakaryocytic lineages was seen in most of the cases. Trilineage dysplasia was observed in 5 cases. Median survival of the entire group was 10.5 months. Eleven patients underwent induction therapy consisting of daunorubicin and cytosine arabinoside +/- 6 thioguanine; 8 patients achieved complete remission (72.6%). Remission duration was 14.5 months. Three patients (27.4%) died secondary to infections during induction therapy. Higher frequencies of trilineage dysplasia and FAB M6 type together with low percentage of peripheral blasts and presence of antecedent hematologic disorders suggest that some of these cases might represent the hypocellular form of acute myeloid leukemia with trilineage dysplasia.