Clonality in myeloproliferative disorders

The incidences of trisomy 8, trisomy 9 and D20S108 deletion in polycythaemia vera: an analysis of blood granulocytes using interphase fluorescence in situ hybridization

We have used interphase fluorescence in situ hybridization (IFISH) to detect trisomy 8, trisomy 9 and 20q deletion in circulating granulocytes from patients with polycythaemia vera (PV). Out of 64 PV patients, 15 (23%) exhibited an abnormality. Two patients had trisomy 9, three had trisomy 8 and 10 patients had hemizygous deletion of D20S108 (a locus in the 20q common deleted region). Aberrant nuclei ranged from 10% to 80% in these 15 cases. There was no correlation between the presence of a marker and sex, age, interval between presentation and IFISH analysis, neutrophil or platelet count or therapy. Conventional marrow cytogenetic karyotype results were available in 23 cases and there was concurrence between these and blood IFISH in 16 cases (13 normal and three with 20q/D20S108 deletion by both methods). Three patients with D20S108 deletion by IFISH were normal by previous marrow cytogenetic testing and four cases with 20q deletion by previous marrow cytogenetics had normal blood granulocytes according to IFISH. Thus, we confirm that trisomies 8 and 9 and deletion of 20q are diagnostically useful markers of PV. IFISH analysis of blood granulocytes is a practical method for detecting these markers, but as an adjunct to, not as a substitute for, conventional marrow cytogenetics.

5q- syndrome presenting chronic myeloproliferative disorders-like manifestation: a case report

A 28-year-old Japanese woman with suspected essential thrombocythemia (ET) had marked thrombocytosis, mild leukocytosis with normal neutrophil alkaline phosphatase activity, and no anemia. She was monitored without being given any medication. Eleven years later, complete blood counts showed no remarkable changes but some non-lobulated mononuclear megakaryocytes were found in the bone marrow. Cytogenetic analysis revealed deletion of the long arm of chromosome 5 (5q-). Subsequently, hemoglobin and platelet counts decreased gradually, splenomegaly appeared and progressed, after which myelofibrosis developed. Acute leukemia developed 16 years after the first documentation of thrombocytosis. 5q- syndrome is known to be a myelodysplastic syndrome (MDS) with unique clinical features and cases with this syndrome presenting with thrombocytosis of more than 1,000 x 10(9)/L but without anemia are rare. Furthermore, it is noteworthy that in this patient transition to acute leukemia occurred following development of myelofibrosis and marked splenomegaly, which are generally observed in blastic crises resulting from chronic myeloproliferative disorders (CMPD). The patient showed features indicative of CMPD rather than of MDS in spite of presenting with 5q- chromosomal abnormality. This case supports the concept of "mixed myelodysplastic and myeloproliferative syndromes" and suggests the possibility of the appearance of CMPD-like manifestations in 5q- syndrome.

Secondary myeloid/natural killer cell precursor acute leukemia following essential thrombocythemia

The de novo leukemic transformation of essential thrombocythemia is a rare event, and usually associated with previous treatments. We describe a patient who received treatments with nitrosourea for long-standing essential thrombocythemia and subsequently developed extramedullary tumors, tentatively diagnosed as lymphoblastic lymphoma. Combination chemotherapy was initially successful, but relapsed with marked bone marrow involvement. Surface marker analysis revealed that the tumor cells had CD5, CD7, CD33, CD34, and CD56 antigens but lacked other T-cell, and B-cell markers. Immunogenotypical studies revealed germline configurations for both T-cell receptors and immunoglobulin genes. These clinical and phenotypical features are consistent with a myeloid/natural killer cell precursor leukemia, a recently proposed distinct clinical entity. To our knowledge, this is the first report of secondary leukemia of myeloid/ natural killer cell precursor origin, and suggest that myeloid/natural killer cell precursor might be a potent target of therapy-related leukemia.

Transformation of essential thrombocythaemia to T cell acute lymphoblastic leukaemia

Leukaemic transformation of essential thrombocythaemia is a rare event and is usually associated with previous treatment with either alkylating agents or radioactive phosphorous. We describe a patient with essential thrombocythaemia who developed an acute leukaemia of T cell phenotype following hydroxyurea therapy. The T cell phenotype of the blasts suggests the target cell for leukaemic transformation was a pluripotential stem cell.

Identification of latent myeloproliferative disease in patients with Budd-Chiari syndrome using X-chromosome inactivation patterns and in vitro erythroid colony formation

Some patients with an early or latent myeloproliferative disorder (MPD) present with Budd-Chiari syndrome (BCS, hepatic vein thrombosis). Cell culture analysis of erythroid progenitors (BFU-E) can be used to discriminate primary from secondary MPD and examination of X-chromosome inactivation (in females) can be used to demonstrate clonality in neoplastic tissues. The present study used these techniques to examine whether a group of 7 female patients who presented with BCS had evidence to support a diagnosis of MPD. Unilateral X-inactivation and therefore clonality can be studied in females heterozygous for X-linked restriction fragment length polymorphisms (RFLP) by differences in methylation between active and inactive chromosomes. Probes for two polymorphic loci, phosphoglycerate kinase (PGK, at Xq13.3 [BstX1 RFLP]) and M27 beta (an anonymous locus DXS255 at Xp11.22 [Pst1 RFLP]) were used to study methylation patterns. All 7 patients were heterozygous using M27 beta and 2/7 were also heterozygous using the PGK probe. Polyclonal patterns of X-inactivation in granulocytes were demonstrated in 3/7, a skewed/monoclonal pattern in 1/7 and aberrant patterns in 3/7 using M27 beta. Two patients who had aberrant patterns of X inactivation with M27 beta demonstrated a skewed/monoclonal pattern with PGK. The results of BFU-E growth patterns and clonality were entirely concordant in 5/6 patients. Thus X-chromosome inactivation patterns, in conjunction with erythroid colony studies, can be used to assist in the diagnosis of an underlying MPD in BCS.

Activated phenotype in neutrophils and monocytes from patients with primary proliferative polycythaemia

AIM

To investigate whether monocytes and neutrophils from patients with primary proliferative polycythaemia (PPP) exhibit increased expression of markers of cell activation and, if so, whether they are associated with the phagocytic activity of these cells and concentrations of circulating cytokines.

METHODS

Expression of CD11b, CD14, CD18, and CD64 on monocytes and neutrophils was assessed by flow cytometry. Phagocytosis was analysed using immunoglobulin opsonised Escherichia coli. Serum concentrations of granulocyte colony stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF) and macrophage CSF (M-CSF) were determined by bioassays, and interferon-gamma (IFN-gamma) by enzyme linked immunosorbent assay (ELISA).

RESULTS

Patients with PPP (n = 18), when compared with normal subjects (n = 10), had increased percentages of CD64+ monocytes (52% v 36%) and neutrophils (42% v 11%) and of CD14+ neutrophils (36% v 18%). Monocytes from patients with PPP exhibited increased expression of CD64 (47 v 26) and of CD11b (65 v 36). These abnormalities were not found in patients with secondary (n = 8) or apparent (n = 13) polycythaemia. The percentage of neutrophils undergoing phagocytosis was higher in patients with PPP (mean 64%; n = 6) than in normal subjects (mean 42%; n = 5). G-CSF, GM-CSF and IFN-gamma concentrations in patients' serum samples were comparable with normal; M-CSF was not detected in any of the samples. There was no correlation between cytokine concentrations and the expression of CD11b, CD14, CD18, and CD64 on patients' phagocytes.

CONCLUSIONS

Increased expression of CD11b and CD64 by monocytes, increased percentages of CD14+ and CD64+ neutrophils and the high phagocytic activity of neutrophils suggests that these cells are activated in vivo in patients with PPP. The phenotypic changes of PPP phagocytes were not associated with increased concentrations of circulating cytokines and probably reflect intrinsic abnormalities within the neoplastic PPP clone.

A new myeloproliferative syndrome

We report here two cases of a previously undescribed myeloproliferative disorder. Both were young adult males who presented with generalized lymphadenopathy, splenomegaly, leukocytosis, polycythemia, and persistent thrombocytopenia. The leukocyte alkaline phosphatase (LAP) score was low in both cases, and the bone marrow was hypercellular without dysplasia or fibrosis, but lacked the Philadelphia chromosome, BCR gene rearrangement, or other karyotypic abnormalities. The clinical course was indolent in each case. One patient died from an unusual "blast crisis" after 12 years, while the second patient remains in a complete hematologic remission on hydroxyurea and alpha interferon 4 years from diagnosis. Interestingly, changes in therapy in this patient have consistently resulted in precise and concerted fluctuations in his blood counts, with the red and white cells cycling together and the platelets and mean corpuscular volume (MCV) changing concomitantly but in the opposite direction. This unique myeloproliferative disorder is distinguishable from all previously described forms of chronic myeloid leukemia and other myeloproliferative syndromes.