[Acute or subacute myelofibrosis].

Nine patients were selected according to the following criteria: 1. Hematological findings consistent with the diagnosis of myelofibrosis with myeloid metaplasia (MMM), except for an excess of blasts in the blood and bone marrow; 2. No previous (silent) phase of MMM. 3. No PH1 chromosome, and 4. No identifiable cause of secondary myelofibrosis. These patients had either an acute or subacute myelofibrosis. The onset of such symptoms as fever, bone pain, hemorrhage and mild splenomegaly was rapid. Terminal acute leukemia or more often progressive bone marrow biopsy showing myelofibrosis with persistence of differentiated myeloid tissue, particularly megacaryocytes. Isotopic studies (59Fe and 51Cr) showed splenic erythroid metaplasia, poor bone marrow 59Fe uptake and increased peripheral red blood cell destruction. This study confirms that malignant myelosclerosis is a well-defined syndrome which must be distinguished from: a) Acute transformation of typical agnogenic myeloid metaplasia even though it was previously undiagnosed (4 cases of MMM illustrating this possibility have been reported); b) Acute myeloblastic leukemia with myelofibrosis; and c) Myelofibrosis secondary to lymphomatous or carcinomatous bone-marrow invasion (2 cases with acute myelofibrosis appearing long after appropriate treatment have been reported).