Nariyoshi Hoshikawa

ACUTE LEUKEMIA OF MEGAKARYOCYTE LINEAGE WITH TUMOR FORMATION: An Autopsy Case of Patient with Down's Syndrome

In this report we present the autopsy findings of acute megakaryoblastic leukemia with tumor formation in a 2‐year‐old female infant with Downs syndrome. Chromosomal analysis of blast cells revealed constitutional anomaly of trisomy 21 and two other related types of abnormal clones. Flow cytometric examination revealed blast cells expressing Ia‐like or HLA‐DR antigens. Postmortem examination showed extensive inffltration of leukemic cells in most of the examined organs, including the bone marrow with myelofibrosis. Tumor masses in the maxillary, frontal and femoral bones and the atria of the heart had undergone massive infiltration of atypical blast cells with an increase in the reticulin network. The final diagnosis was confirmed by ultrastructural cytochemistry of the platelet peroxidase reaction as well as by immunological staining utilizing anti‐platelet glycoprotein IIb/IIIa, anti‐platelet factor 4 and anti‐β‐thromboglobulin antibodies for the blast cells. It seems likely that platelet‐derived growth factor, secondary to an increase in the reticulin network, plays a major role in myelofibrosis of acute megakaryoblastic leukemia with tumor formation. ACTA PATHOL JPN 38: 193–207, 1988.

Four autopsy cases of acute viral myocarditis

SummaryFour autopsy cases of acute idiopathic myocarditis were studied by means of immunofluorescent techniques and electron microscopy. All patients died of acute cardiac failure of sudden onset 2–7 days after the appearance of common cold symptoms. Postmortem examination revealed eccentric cardiac hypertropy and pericarditis in all cases. Two of the four cases showed severe necrosis of the myocardium with infiltration by mononuclear cells. Coxsackie B virus antigens were detected in three cases and virus particles were demonstrated electron-microscopically in three cases.

STUDIES ON THE INITIAL REACTIVE SITES FOR PLATELET ACTIVATION

The binding sites for cationized ferritin or ferritin‐conjugated wheat germ agglutinin on the cell surface were studied on platelets before or after fixation in glutaraldehyde. The effects of neuraminidase on the binding sites were also demonstrated after fixation of the platelets. Changes in the binding sites and distribution pattern due to exposure to these ligands were further investigated in the unfixed platelets under a variety of conditions such as incubation time and medium. The fixed platelets incubated with either ligand showed an even and continuous distribution of particles on the cell surface. In the unfixed platelets, the ligands were rapidly moved and aggregated probably by lateral migration after binding to the cell surface. The ligands were also bound to the membrane surface and simultaneously appeared in the interior of the open canalicular system. As the binding sites were moved on the cell surface as well as into the open canalicular system, morphological changes suggestive of platelet secretion occurred. The binding sites of either ligand were redistributed on the platelet cell surface. Glycoprotein lb, thought to be the receptor site for wheat germ agglutinin on the cell surface, contains sialic acids that contribute to the negative charge of platelets. Therefore, glycoprotein lb may play an important role as the initial reactive site for thrombotic stimuli.