[Megakaryocytic leukemia with thrombocytosis]

A 62-year-old man was admitted to our hospital with exertional dyspnea. On admission, neither hepatosplenomegaly nor lymphadenopathy were noted. Laboratory data revealed anemia (Hb, 4.8 g/dl), leukopenia (2,800 microliters) and a normal platelet count (21 X 10(4)/microliters). The immature blast cells in the peripheral blood were 15%, which increased to 32% during his clinical course. On cytochemical studies, the blast cells had no staining with peroxidase, alpha-naphthyl-butyrate esterase and PAS, although acid phosphatase was positive. More than 58% of the blasts were identified as being of megakaryocytic lineage by platelet peroxidase and by tests with monoclonal GP IIb/IIIa antibody. Bone marrow biopsy disclosed marked fibrosis. However, the patient constantly had normal counts of platelets ranging from 21 X 10(4) to 63 X 10(4)/microliters. This case provides evidence that the megakaryocytic leukemias can be categorized into two types, which are characterized by either undifferentiated or differentiated megakaryocytic leukemia cells.

Establishment of a human leukaemic cell line (CMK) with megakaryocytic characteristics from a Down's syndrome patient with acute megakaryoblastic leukaemia

A new megakaryoblastic cell line (CMK), which also exhibits erythroid and myeloid markers, was established from a Down's syndrome patient suffering from acute megakaryoblastic leukaemia. The CMK cells were found to be positive in reactions with anti-platelet antibodies (anti-glycoproteins IIb/IIIa and Ib, and Plt-1). Platelet peroxidase (PPO) reactivity was found to be associated with the nuclear envelope and the endoplasmic reticulum but not with the Golgi apparatus. Some cells possessed cytoplasmic granules with the characteristics of alpha-granules and demarcation membranes. Karyotyping revealed near-tetraploidy (modal chromosome number of 95; ranging 87-98) and a translocation der(17)t(11;17), also found in the original leukaemic cells, confirming that the cells were derived from the patient's malignant blasts. The CMK cells were also found to be positive in reaction with anti-glycophorin A antibody, as well as with anti-myeloid antibodies (MY4, MY7 and MY9). Treatment of CMK cells with phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) greatly enhanced the reactivity with anti-platelet antibodies, increased the number of cells in which cytoplasm was dissociated into numerous segments and suppressed the reactivity with anti-glycophorin A. The proliferation of CMK cells was stimulated by interleukin-3 (IL-3) and granulocyte-macrophage colony stimulation factor (GM-CSF). This cell line should be a useful tool for analysing the basis of the afferent association between megakaryoblastic leukaemia and Down's syndrome, as well as for further study of megakaryocytic differentiation.

[Fatal cerebral aspergillosis in acute megakaryoblastic leukemia]

A 13 year-old girl was diagnosed as having acute megakaryoblastic leukemia. A serious infectious syndrome appeared during the chemotherapy, not improved by broad spectrum antibiotic therapy. A pulmonary aspergillosis was diagnosed one month later by a second bronchoalveolar lavage. A treatment with Itraconazole, a new antifungal triazole, was started. Despite this treatment, the child died after 3 days. Death was due to multiple aspergillus abscesses disseminated in the brain leading to coma and transtentorial herniation. Autopsy confirmed the cerebral aspergillus abscesses and showed also the dramatic dissemination of aspergillosis in the body. Diagnosis and treatment to aspergillosis in immunosuppressed patients should be made early to improve prognosis.

Diagnosis and successful treatment of fusariosis in the compromised host

We present six cases of fusariosis caused by Fusarium solani that were diagnosed over a three-year period in 166 adult patients undergoing chemotherapy for acute leukemia. Necrotic skin lesions were evident in four patients, fungemia in three, and a deep cellulitis around a great toe nail at the time of a febrile illness in two. The mean minimal inhibitory concentration (MIC) of amphotericin B was 3.3 micrograms/mL and of miconazole, 5.3 micrograms/mL; all isolates were resistant to 5-fluorocytosine. All patients received amphotericin B (1.0-1.5 mg/kg per d) plus 5-fluorocytosine. In contrast to results found in the literature, five patients had resolution of their infections, and the one patient who died had necropsy evidence of disseminated fusariosis. Review of our cases and of the literature did not reveal a definitive source for the organism or its portal of entry. Fusarium spp. must be recognized as opportunistic pathogens that cause a potentially fatal infection in compromised patients.

Amsacrine is safe in patients with ventricular ectopy

Amsacrine is an active antileukemic agent known to induce cardiac arrhythmias, although the incidence of these cardiac events is low. Rhythm abnormalities associated with amsacrine use include the development of fatal tachyarrhythmias, but this risk can be minimized by ensuring a normal serum potassium level prior to drug administration. Even though amsacrine has been given safely to patients with pre-existing supraventricular arrhythmias, its safety in patients with ventricular ectopy has not been addressed. We describe two patients who underwent treatment with amsacrine without developing life-threatening dysrhythmias and show that ventricular ectopy does not contraindicate therapy with this agent.

Dicentric chromosome in the bone marrow of a child with megakaryoblastic leukaemia and Down's syndrome

A two year old girl with Down's syndrome (constitutional karyotype: 47 + 21), presenting with pancytopenia, developed acute megakaryoblastic leukaemia (AMKL). Her bone marrow contained an abnormal clone with a novel dicentric chromosome derived from chromosomes 5 and 7 (karyotype 46, XX, -5, -7, +dic (5;7) (p 13; p 11.2), +21. This case provides further evidence for a connection between chromosome 21 and this unusual form of childhood leukaemia, and raises questions about the loss of short arm material from chromosomes 5 and 7 compared with the more usual monosomy or long arm loss.

Acute megakaryoblastic leukemia associated with mosaic Down's syndrome

There have been several reports of the association between Down's Syndrome and acute megakaryoblastic (M7) leukemia (AMKL). The diagnosis of this rare form of leukemia has been better delineated by the use of the platelet peroxidase reaction and the antifactor VIII antibody immunoperoxidase test. In the past, the prognosis of patients with a combination of Down's Syndrome and AMKL has been extremely poor, with a median survival of 6.9 months for 11 reported cases in the literature. The present report reviews the previously reported cases and describes a unique patient with mosaic Down's syndrome and AMKL with favorable response to therapy.

The c-sis gene expression in cells from a patient with acute megakaryoblastic leukemia and Down's syndrome

The c-sis gene expression in leukemia cells from a patient with acute megakaryoblastic leukemia and Down's syndrome was studied. The leukemia blasts were identified as megakaryoblasts by the platelet peroxidase reaction and the reactivity against antiplatelet monoclonal antibodies. Leukemia cells obtained from peripheral blood or bone marrow specimens before and after initiation of chemotherapy were analyzed for c-sis gene expression by the RNA-DNA dot blot hybridization. Although the level varied, the mRNA of the c-sis gene was detected in all megakaryoblastic leukemia cells obtained at different clinical stages. The c-sis mRNA level in cells obtained after relapse was higher than that obtained before the initiation of therapy. The 25S c-sis mRNA was detected in a megakaryoblastic leukemia cell line established from this patient. The role of the expression of the c-sis gene in acute megakaryoblastic leukemia cells is discussed.

Splenic rupture in acute megakaryoblastic leukemia

A 43-year-old man with pancytopenia and circulating blast cells was found to have acute megakaryoblastic leukemia. Bone marrow biopsy disclosed reticulin fibrosis with infiltration of blast cells. Cytogenic study showed 48,XY,+15,+18. The megakaryocytic origin of blast cells was confirmed by platelet peroxidase reaction at ultrastructural level. The spleen which had not been felt on admission increased in size rapidly and ruptured abruptly. This appears to be the first reported case of a splenic rupture associated with acute megakaryoblastic leukemia.

Osteolytic tumors in acute megakaryoblastic leukemia

A patient with soft tissue tumors and osteolytic bone lesions produced by acute megakaryoblastic leukemia is described. This appears to be the first report of this complication. The management and significance of this presentation are discussed.