Disseminated intravascular coagulation in a patient with acute myeloid leukemia. Ultrastructural evidence of hypercoagulation in bone marrow.

The bone marrow of a 53-year-old woman with acute myeloid leukemia (AML) with disseminated intravascular coagulation was investigated by transmission electron microscopy. The patient had a preceding granulocytic sarcoma, and subclinical disseminated intravascular coagulation occurred concomitantly with the development of AML. Ultrastructural findings of the bone marrow at the onset of AML revealed the following: (1) The cytoplasm of the leukemic cells showed frequent fragmentation, resulting in the formation of abundant cytoplasmic fragments. (2) These cytoplasmic fragments were surrounded by abundant fibrin fibers, forming the fibrin-cytoplasmic fragment complex (FCF complex). (3) Slight fibrin deposition was seen around the leukemic cells and in the intercellular space of the bone marrow. Fibrin deposition in the bone marrow is thought to represent morphologic evidence of disseminated intravascular coagulation. The damage on the leukemic cell surface due to the cytoplasmic fragmentation seems to be closely related to the development of disseminated intravascular coagulation.