A rare, acute myeloid leukemia characterized by no significant myeloid maturation and more than 90% blast cells in the non-erythroid population. Various degrees of anemia, thrombocytopenia, or pancytopenia are present. Frequent clinical manifestations include fatigue, fever, bleeding disorders, and organomegaly, especially hepatosplenomegaly.

Inflammatory changes in the synovial membranes and articular structures with widespread fibrinoid degeneration of the collagen fibers in mesenchymal tissues, as well as atrophy and rarefaction of bony structures.