[Acute myelofibrosis: apropos of a case with immunocytochemical and ultrastructural studies]

We report a case of acute myelofibrosis. This is a rare myeloproliferative disorder characterized by pancytopenia, minimal or absent anisopoikilocytosis, bone marrow fibrosis with hyperplasia and immaturity of the three main cellular lines with megakaryocyte predominance, absence of splenomegaly and rapidly fatal course. We discuss its relationship with acute megakaryocytic leukemia, as its blast elements correspond to megakaryocytes when ultrastructural and antifactor VIII immunoperoxidase techniques are used; these techniques disclose alpha granules and cell demarcating membranes.