title: Hypomegakaryocytic thrombocytopenia (HMT): an immune-mediated bone marrow failure characterized by an increased number of PNH-phenotype cells and high plasma thrombopoietin levels.
abstract: Patients with mild hypomegakaryocytic thrombocytopenia (HMT) that does not meet the diagnostic criteria for a definite disease entity may potentially progress to aplastic anaemia (AA) that is refractory to therapy. To clarify the clinical picture of HMT, we prospectively followed 25 HMT patients with white blood cell count >3·0 × 109/l, haemoglobin level >100 g/l and platelet count of <100·0 × 109/l in the absence of morphological and karyotypic abnormalities in the bone marrow. Glycosylphosphatidylinositol-anchored protein-deficient blood cells [paroxysmal nocturnal haemoglobinuria (PNH)-type cells] were detected in 7 of the 25 (28%) patients and elevated plasma thrombopoietin (TPO, also termed THPO) levels (>320 pg/ml) were observed in 11 (44%) patients. Five (four PNH+ and one PNH-) of six TPOhighpatients who were treated with ciclosporin (CsA) showed improvement. Among the 21 patients who were followed without treatment, thrombocytopenia progressed in four of ten TPOlowpatients and four of 11 TPOhighpatients. The 3-year failure-free survival rate of the CsA-treated TPOhighpatients (100%) was significantly higher than that of the untreated TPOhighpatients (20%). These results suggest that a significant population of HMT patients has an immune pathophysiology that is similar to AA and may be improved by early therapeutic intervention with CsA.
authors.affiliation: Department of Haematology, Kanazawa University Hospital, Kanazawa, Japan.
authors.forename: Chizuru
authors.initials: C
authors.lastname: Saito
authors.affiliation: Department of Haematology, Kanazawa University Hospital, Kanazawa, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Ishiyama
authors.affiliation: Division of Transfusion Medicine, Kanazawa University Hospital, Kanazawa, Japan.
authors.forename: Hirohito
authors.initials: H
authors.lastname: Yamazaki
authors.affiliation: Division of Transfusion Medicine, Kanazawa University Hospital, Kanazawa, Japan.|Cellular Transplantation Biology, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Zaimoku
authors.affiliation: Cellular Transplantation Biology, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan. snakao8205@staff.kanazawa-u.ac.jp.
authors.forename: Shinji
authors.initials: S
authors.lastname: Nakao
mesh_terms: D000328:Adult; D000368:Aged; D000741:Anemia, Aplastic / Q000175:diagnosis; D001853:Bone Marrow / Q000276:immunology / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006457:Hemoglobinuria, Paroxysmal / Q000175:diagnosis; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008297:Male; D008533:Megakaryocytes / Q000276:immunology / Q000473:pathology*; D008875:Middle Aged; D010641:Phenotype; D013921:Thrombocytopenia / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology* / Q000401:mortality; D013926:Thrombopoietin / Q000097:blood; D016896:Treatment Outcome
chemical_list: D007166:Immunosuppressive Agents; D013926:Thrombopoietin
keywords: PNH-type cells; ciclosporin; hypomegakaryocytic thrombocytopenia; thrombopoietin