A case of myelodysplasia with eosinophilia having a translocation t(5;12) (q31;q13) restricted to myeloid cells but not involving eosinophils

A Novel IL3-ETV6 Fusion in Chronic Eosinophilic Leukemia Not Otherwise Specified With t(5; 12) (q31; p13): A Case Report and Literature Review

Chronic eosinophilic leukemia not otherwise specified (CEL-NOS) is classified as Myeloproliterative Neoplasms (MPN) and refers to chronic eosinophilic leukemia with some atypical recurrent genetic evidence(1). A rare fusion of ACSL6-ETV6 was previously identified in patients with the t(5;12) (q31; p13) karyotype(2). Here, we report a case of CEL-NOS with a translocation of t(5;12) (q31; p13) and identify IL3-ETV6 transcription, which has not been identified in hematologic diseases. In this patient, eosinophilia was observed. And compared with CEL-NOS patients without ETV6 fusion, a higher mRNA expression level of IL3 was found. After failing treatment with dasatinib, the patient was given hydroxyurea (HU). Subsequently his white blood cell (WBC) and eosinophils decreased significantly and remained in the normal range until publication. Due to the side effects, treatment with HU was replaced by PEG-interferon (PEG-IFN). What’s more, we summarized the case in our study and 21 patients with the karyotype of t(5; 12) (q31; p13) reported by other groups. It was found that most of them had similar clinical manifestations of eosinophilia and tyrosine kinase inhibitor (TKI) insensitivity. The ectopic mRNA expression of IL3 may be the main cause of eosinophilia, and HU and prednisone acetate (PAT), as well as IFN, were considered treatments for this group.

Eosinophilic disorders: molecular pathogenesis, new classification, and modern therapy

Before the 1990s, lack of evidence for a reactive cause of hypereosinophilia or chronic eosinophilic leukemia (e.g. presence of a clonal cytogenetic abnormality or increased blood or bone marrow blasts) resulted in diagnosticians characterizing such nebulous cases as 'idiopathic hypereosinophilic syndrome (HES)'. However, over the last decade, significant advances in our understanding of the molecular pathophysiology of eosinophilic disorders have shifted an increasing proportion of cases from this idiopathic HES 'pool' to genetically defined eosinophilic diseases with recurrent molecular abnormalities. The majority of these genetic lesions result in constitutively activated fusion tyrosine kinases, the phenotypic consequence of which is an eosinophilia-associated myeloid disorder. Most notable among these is the recent discovery of the cryptic FIP1L1-PDGFRA gene fusion in karyotypically normal patients with systemic mast cell disease with eosinophilia or idiopathic HES, redefining these diseases as clonal eosinophilias. Rearrangements involving PDGFRA and PDGFRB in eosinophilic chronic myeloproliferative disorders, and of fibroblast growth factor receptor 1 (FGFR1) in the 8p11 stem cell myeloproliferative syndrome constitute additional examples of specific genetic alterations linked to clonal eosinophilia. The identification of populations of aberrant T-lymphocytes secreting eosinophilopoietic cytokines such as interleukin-5 establish a pathophysiologic basis for cases of lymphocyte-mediated hypereosinophilia. This recent revival in understanding the biologic basis of eosinophilic disorders has permitted more genetic specificity in the classification of these diseases, and has translated into successful therapeutic approaches with targeted agents such as imatinib mesylate and recombinant anti-IL-5 antibody.

Targeted treatment of hypereosinophilic syndromes and chronic eosinophilic leukemias with imatinib mesylate

Idiopathic hypereosinophilic syndrome (HES) and chronic eosinophilia leukemia (CEL) represent the most recent additions to the list of molecularly defined chronic myeloproliferative disorders. Beginning with the observation that imatinib mesylate (Gleevec) could elicit rapid and complete hematologic remissions in a proportion of patients with HES, a reverse bedside-to-bench translational research effort led to the discovery of FIP1L1-PDGFRA, a novel fusion gene on chromosome 4q12 whose product is an imatinib-sensitive protein tyrosine kinase. FIP1L1-PDGFRA is the first description of a gain-of-function fusion gene derived from an interstitial chromosomal deletion rather than a reciprocal translocation. Empiric use of imatinib in HES and CEL provides a dramatic example of how the development of targeted therapeutics can provide tremendous insight into the molecular etiology of what appear to be a diverse and otherwise indecipherable collection of diseases. In this review, we discuss the role of imatinib in HES/CEL and other malignancies characterized by constitutively activated tyrosine kinases, and examine molecular features of the FIP1L1-PDGFRA fusion.

A case of chronic myelomonocytic leukemia with severe eosinophilia having t(5;12)(q31;p13) with t(1;7)(q10;p10)

We describe an unusual case of chronic myelomonocytic leukemia with severe eosinophilia having t(5;12)(q31;p13) with t(1;7)(q10;p10). The eosinophilic proliferation was severe in peripheral blood and bone marrow, and they revealed marked dysplastic features. We performed fluorescence in situ hybridization (FISH) and immunohistochemistry to evaluate the clonality of eosinophils. The eosinophils were stained positively to platelet-derived growth factor receptor-beta. By FISH using chromosome 1 satellite probe and chromosome 1q telomere probe, the eosinophils were proved to belong to the malignant clone.

Molecular classification and pathogenesis of eosinophilic disorders: 2005 update

Use of the term "idiopathic hypereosinophilic syndrome (HES)" has highlighted our basic lack of understanding of the molecular pathophysiology of eosinophilic disorders. However, over the last 10 years, the study of hypereosinophilia has enjoyed a revival. This interest has been rekindled by two factors: (1) the development of increasingly sophisticated molecular biology techniques that have unmasked recurrent genetic abnormalities linked to eosinophilia, and (2) the successful application of targeted therapy with agents such as imatinib to treat eosinophilic diseases. To date, most of these recurrent molecular abnormalities have resulted in constitutively activated fusion tyrosine kinases whose phenotypic consequence is an eosinophilia-associated myeloid disorder. Most notable among these are rearrangements of platelet-derived growth factor receptors alpha and beta (PDGFRalpha, PDGFRbeta), which define a small subset of patients with eosinophilic chronic myeloproliferative disorders (MPDs) and/or overlap myelodysplastic syndrome/MPD syndromes, including chronic myelomonocytic leukemia. Discovery of the cryptic FIP1L1-PDGFRA gene fusion in cytogenetically normal patients with systemic mast cell disease with eosinophilia or idiopathic HES has redefined these diseases as clonal eosinophilias. A growing list of fibroblast growth factor receptor 1 fusion partners has similarly emerged in the 8p11 myeloproliferative syndromes, which are often characterized by elevated eosinophil counts. Herein the focus is on the molecular gains made in these MPD-type eosinophilias, and the classification and clinicopathological issues related to hypereosinophilic syndromes, including the lymphocyte variant. Success in establishing the molecular basis of a group of once seemingly heterogeneous diseases has now the laid the foundation for establishing a semi-molecular classification scheme of eosinophilic disorders.

Targeted treatment of hypereosinophilic syndromes and chronic eosinophilic leukemias with imatinib mesylate

Idiopathic hypereosinophilic syndrome (HES) and chronic eosinophilia leukemia (CEL) represent the most recent additions to the list of molecularly defined chronic myeloproliferative disorders. Beginning with the observation that imatinib mesylate (Gleevec) could elicit rapid and complete hematologic remissions in a proportion of patients with HES, a reverse bedside-to-bench translational research effort led to the discovery of FIP1L1-PDGFRA, a novel fusion gene on chromosome 4q12 whose product is an imatinib-sensitive protein tyrosine kinase. FIP1L1-PDGFRA is the first description of a gain-of-function fusion gene derived from an interstitial chromosomal deletion rather than a reciprocal translocation. Empiric use of imatinib in HES and CEL provides a dramatic example of how the development of targeted therapeutics can provide tremendous insight into the molecular etiology of what appear to be a diverse and otherwise indecipherable collection of diseases. In this review, we discuss the role of imatinib in HES/CEL and other malignancies characterized by constitutively activated tyrosine kinases, and examine molecular features of the FIP1L1-PDGFRA fusion.

Cloning of the t(1;5)(q23;q33) in a myeloproliferative disorder associated with eosinophilia: involvement of PDGFRB and response to imatinib

Eosinophilia is common in myeloproliferative disorders (MPDs) with abnormalities of chromosome band 5q31-33, including those that present with t(1;5)(q23;q33). With the development of rational drug therapy, characterization of the molecular targets for these translocations could guide treatment and affect patient survival. We cloned the t(1;5)(q23;q33) and showed that it fuses platelet-derived growth factor receptor beta (PDGFRB) to the coiled-coil domains of a novel partner protein, myomegalin. Using two-color interphase fluorescence in situ hybridization (FISH), we also demonstrated that the eosinophils are clonal in these disorders. Imatinib mesylate has recently been shown to be efficacious in MPDs with PDGFR activation. Therefore, following our molecular studies, we were able to redirect this patient's treatment. Although she had refractory and progressive disease, once imatinib was started, complete clinical and hematologic remission, as well as major cytogenetic response, was achieved. Given the therapeutic implications, our findings stress the need to aggressively investigate the molecular basis of these diseases, with emphasis on the PDGFR family.

The FIP1L1-PDGFRalpha fusion tyrosine kinase in hypereosinophilic syndrome and chronic eosinophilic leukemia: implications for diagnosis, classification, and management

Idiopathic hypereosinophilic syndrome (HES) and chronic eosinophilic leukemia (CEL) comprise a spectrum of indolent to aggressive diseases characterized by unexplained, persistent hypereosinophilia. These disorders have eluded a unique molecular explanation, and therapy has primarily been oriented toward palliation of symptoms related to organ involvement. Recent reports indicate that HES and CEL are imatinib-responsive malignancies, with rapid and complete hematologic remissions observed at lower doses than used in chronic myelogenous leukemia (CML). These BCR-ABL-negative cases lack activating mutations or abnormal fusions involving other known target genes of imatinib, implicating a novel tyrosine kinase in their pathogenesis. A bedside-to-benchtop translational research effort led to the identification of a constitutively activated fusion tyrosine kinase on chromosome 4q12, derived from an interstitial deletion, that fuses the platelet-derived growth factor receptor-alpha gene (PDGFRA) to an uncharacterized human gene FIP1-like-1 (FIP1L1). However, not all HES and CEL patients respond to imatinib, suggesting disease heterogeneity. Furthermore, approximately 40% of responding patients lack the FIP1L1-PDGFRA fusion, suggesting genetic heterogeneity. This review examines the current state of knowledge of HES and CEL and the implications of the FIP1L1-PDGFRA discovery on their diagnosis, classification, and management.

Chromosomal rearrangement in Down syndrome with acute myeloid leukemia

The incidence of acute leukemia in children with Down syndrome (DS) is high as compared to general population. Recent findings have demonstrated that DS children with acute myeloid leukemia (AML) have the highest event free survival rates with high dose cytosine arabinoside (Ara-C). We present 3 year-old DS female child with AML-M5, whose chromosomal analysis revealed constitutional t(21;21) alongwith del(5)(q31q33) and a unique translocation t(16;20)(q13;q12). After chemotherapy, child achieved complete clinical remission. Karyotype analysis of remission marrow showed disappearance of abnormal clone of der(20) t(16;20)(q13;q12), del(5q) indicating cytogenetic remission too. This case alongwith supportive literature indicate that pediatric DS-AML is a distinct biologic sub-group differs from that of non-DS-AML with respect to chemosensitivity.

Prevalence and clinical characteristics of myelodysplastic syndrome with bone marrow eosinophilia or basophilia

By retrospectively analyzing 288 patients with de novo myelodysplastic syndrome (MDS), we sought to determine the prevalence and clinical characteristics of bone marrow eosinophilia and basophilia that were detected at presentation. Bone marrow eosinophilia and basophilia were defined as a differential count of each cell type exceeding 5.0% and 1.0%, respectively. Of 288 patients with MDS, 36 (12.5%) fulfilled this criterion for bone marrow eosinophilia (MDS-Eos); 34 patients (11.8%) showed basophilia (MDS-Bas), and 11 (3.8%) satisfied both criteria (MDS-EosBas). The remaining 229 patients had neither eosinophilia nor basophilia in their bone marrow (MDS(-/-)) at presentation. Cytogenetic analysis was carried out on unstimulated bone marrow cells obtained from 264 patients. When the cytogenetic categorization of the IPSS (International Prognostic Scoring System) for MDS was applied, significantly higher numbers of MDS-Eos and MDS-Bas patients had chromosomal abnormalities carrying intermediate or poor prognosis, compared with the MDS(-/-) patients. Specific chromosomal abnormalities and complex karyotypes were associated with MDS-Eos and/or MDS-Bas. In accordance with these results, the overall survival rate was significantly lower, and the evolution to acute myelogenous leukemia (AML) occurred more frequently in the MDS-Eos and MDS-Bas than in the MDS(-/-) patients. Multivariate analysis demonstrated that bone marrow basophilia was an independent risk factor for evolution to AML. Our study indicates that bone marrow eosinophilia and basophilia in patients with MDS predict a poorer prognosis.

Chronic myelocytic leukemia with eosinophilia, t(9;12)(q34;p13), and ETV6-ABL gene rearrangement: case report and review of the literature

Chronic myelocytic leukemia (CML) is a chronic myeloproliferative disorder characterized by cytogenetic or molecular evidence of Philadelphia (Ph) chromosome, t(9;22)(q34;q11). Mild to moderate eosinophilia is commonly seen in CML. However, eosinophilia as a dominant feature of CML is extremely rare. We describe a case of Ph(-) CML with eosinophilia. Loeffler endocarditis, and t(9;12)(q34;p13) that resulted in an ETV6-ABL gene rearrangement/fusion identified to the best of our knowledge, for the first time by using commercially available fluorescence in situ hybridization probes.

Response to imatinib mesylate in patients with chronic myeloproliferative diseases with rearrangements of the platelet-derived growth factor receptor beta

BACKGROUND

A small proportion of patients with chronic myeloproliferative diseases have constitutive activation of the gene for platelet-derived growth factor receptor beta (PDGFRB), which encodes a receptor tyrosine kinase. The gene is located on chromosome 5q33, and the activation is usually caused by a t(5;12)(q33;p13) translocation associated with an ETV6-PDGFRB fusion gene. The tyrosine kinase inhibitor imatinib mesylate specifically inhibits ABL, PDGFR, and KIT kinases and has impressive clinical efficacy in BCR-ABL-positive chronic myeloid leukemia.

METHODS

We treated four patients who had chronic myeloproliferative diseases and chromosomal translocations involving 5q33 with imatinib mesylate (400 mg daily). Three of the four patients presented with leukocytosis and eosinophilia; their leukemia cells carried the ETV6-PDGFRB fusion gene. The fourth patient had leukocytosis, eosinophilia, and a t(5;12) translocation involving PDGFRB and an unknown partner gene; he also had extensive raised, ulcerated skin lesions that had been present for a long time.

RESULTS

In all four patients, a normal blood count was achieved within four weeks after treatment began. In the patient with skin disease, the lesions began to resolve shortly after treatment began. The t(5;12) translocation was undetectable by 12 weeks in three patients and by 36 weeks in the fourth patient. In the three patients with the ETV6-PDGFRB fusion gene, the transcript level decreased, and in one patient, it became undetectable by 36 weeks. All responses were durable at 9 to 12 months of follow-up.

CONCLUSIONS

Imatinib mesylate induces durable responses in patients with chronic myeloproliferative diseases associated with activation of PDGFRB.

Asthma genetics

Asthma is the most common chronic childhood disease in developed nations and is a complex disease that has high social and economic costs. Asthma and its associated intermediate phenotypes are under a substantial degree of genetic control. Identifying the genes underlying asthma offers a means of better understanding its pathogenesis, with the promise of improving preventive strategies, diagnostic tools, and therapies. A number of chromosomal regions containing genes influencing asthma and atopy have been identified consistently by different groups, and a role for several candidate genes has been established.

Childhood myeloid leukaemias

Childhood myeloid leukaemias are a diverse collection of conditions. Although many are also seen in adults, some are peculiar to childhood. In childhood AML, as in adults, cytogenetic abnormalities are associated with specific clinical features and define prognostic groups. In infants under 1 year with AML, the incidence of 11q23 abnormalities is particularly high. The finding of identical 11q23 breakpoints in infant leukaemia as in therapy-related leukaemias suggests a role for in utero exposure to topoisomerase II inhibitors. There are a number of constitutional disorders that predispose children to develop AML, usually with a preceding myelodysplastic phase. Monosomy (or deletion of the long arm) of chromosome 7 is the most frequent chromosome abnormality in the bone marrow of such patients. Abnormalities of chromosome 7 are also common cytogenetic findings in all morphological subgroups of childhood myelodysplasia, either as a primary abnormality or associated with disease progression.

The relationship between the myelodysplastic syndromes and the myeloproliferative disorders

As a result of clonal evolution typical cases of one of the myelodysplastic syndromes may develop myeloproliferative features. Similarly, typical cases of one of the myeloproliferative disorders may develop dysplastic features, either as part of the natural history of the disease or as a result of exposure to mutagenic drugs or isotopes. There is also an important group of "overlap syndromes" in which cases, at presentation, have both dysplastic and proliferative features. Chronic myelomonocytic leukaemia and many cases of atypical chronic myeloid leukaemia, juvenile chronic myeloid leukaemia and the childhood monosomy 7 syndrome are "overlap syndromes". In addition, a significant minority of cases which fit the generally agreed criteria for a diagnosis of one of the myelodysplastic syndromes (refractory anaemia, refractory anaemia with ring sideroblasts or refractory anaemia with excess of blasts) also have thrombocytosis, neutrophilia, monocytosis, eosinophilia or basophilia.

Familial eosinophilia maps to the cytokine gene cluster on human chromosomal region 5q31-q33

Familial eosinophilia (FE) is an autosomal dominant disorder characterized by peripheral hypereosinophilia of unidentifiable cause with or without other organ involvement. To localize the gene for FE, we performed a genomewide search in a large U.S. kindred, using 312 different polymorphic markers. Seventeen affected subjects, 28 unaffected bloodline relatives, and 8 spouses were genotyped. The initial linkage results from the genome scan provided evidence for linkage on chromosome 5q31-q33. Additional genotyping of genetic markers located in this specific region demonstrated significant evidence that the FE locus is situated between the chromosome 5q markers D5S642 and D5S816 (multipoint LOD score of 6.49). Notably, this region contains the cytokine gene cluster, which includes three genes-namely, those for interleukin (IL)-3, IL-5, and granulocyte/macrophage colony-stimulating factor (GM-CSF)-whose products play important roles in the development and proliferation of eosinophils. These three cytokine genes were screened for potential disease-specific mutations by resequencing of a subgroup of individuals from the present kindred. No functional sequence polymorphisms were found within the promoter, the exons, or the introns of any of these genes or within the IL-3/GM-CSF enhancer, suggesting that the primary defect in FE is not caused by a mutation in any one of these genes but, rather, is caused by another gene in the area.

Fusion of the Platelet-Derived Growth Factor Receptor β to a Novel Gene CEV14 in Acute Myelogenous Leukemia After Clonal Evolution

Chromosomal translocations involving band 5q31-35 occur in several hematologic disorders. A clone with a t(5; 14)(q33; q32) translocation appeared at the relapse phase in a patient with acute myelogenous leukemia who exhibited a sole chromosomal translocation, t(7; 11), at initial diagnosis. After the appearance of this clone, the leukemia progressed with marked eosinophilia, and combination chemotherapy was ineffective. Southern blot analysis showed a rearrangement of the platelet-derived growth factor receptor β (PDGFRβ) gene at 5q33 which was not observed at initial diagnosis. This translocation resulted in a chimeric transcript fusing the PDGFRβ gene on 5q33 with a novel gene, CEV14, located at 14q32. Expression of the 5′ region of the PDGFRβ cDNA, upstream of the breakpoint, was not detected. However, the 3′ region of PDGFRβ, which was transcribed as part of the CEV14-PDGFRβ fusion gene, was detected. A partial cDNA for a novel gene, CEV14, includes a leucine zipper motif and putative thyroid hormone receptor interacting domain and is expressed in a wide range of tissues. The expression of a CEV14-PDGFRβ fusion gene in association with aggressive leukemia progression suggests that this protein has oncogenic potential.

Fusion of the Platelet-Derived Growth Factor Receptor β to a Novel Gene CEV14 in Acute Myelogenous Leukemia After Clonal Evolution

Chromosomal translocations involving band 5q31-35 occur in several hematologic disorders. A clone with a t(5; 14)(q33; q32) translocation appeared at the relapse phase in a patient with acute myelogenous leukemia who exhibited a sole chromosomal translocation, t(7; 11), at initial diagnosis. After the appearance of this clone, the leukemia progressed with marked eosinophilia, and combination chemotherapy was ineffective. Southern blot analysis showed a rearrangement of the platelet-derived growth factor receptor β (PDGFRβ) gene at 5q33 which was not observed at initial diagnosis. This translocation resulted in a chimeric transcript fusing the PDGFRβ gene on 5q33 with a novel gene, CEV14, located at 14q32. Expression of the 5′ region of the PDGFRβ cDNA, upstream of the breakpoint, was not detected. However, the 3′ region of PDGFRβ, which was transcribed as part of the CEV14-PDGFRβ fusion gene, was detected. A partial cDNA for a novel gene, CEV14, includes a leucine zipper motif and putative thyroid hormone receptor interacting domain and is expressed in a wide range of tissues. The expression of a CEV14-PDGFRβ fusion gene in association with aggressive leukemia progression suggests that this protein has oncogenic potential.

Clonal eosinophilic disorders and the hypereosinophilic syndrome

An increase in the blood eosinophil count may occur in a number of disease states including allergies, parasitic infections, vascular disease and as a reaction to the presence of malignant tumours. This article defines those disorders that are not purely reactive, and describes in detail the diagnosis and features of clonal eosinophilic disorders and the hypereosinophilic syndrome. The clonal disorders that are associated with eosinophilia are discussed, in particular the acute and chronic eosinophilic leukaemias and clonal eosinophilias in association with acute myeloid leukaemia, myeloproliferative disorders and myelodysplastic syndromes. Whether eosinophilia is produced by a clonal or reactive disorder, the end result can often be the same, i.e. end organ damage produced by sustained hypereosinophilia in the presence of eosinophil activation. When no cause for the eosinophilia leading to the end organ damage is found, this disease is termed 'idiopathic hypereosinophilic syndrome'. Its pathogenesis, clinical features and management are discussed with particular reference to the possibility of it being a T-cell-associated disorder.

Diagnostic and prognostic significance of cytogenetics in adult primary myelodysplastic syndromes

Cytogenetic analysis has proven to be a mandatory part of the diagnosis of myelodysplastic syndromes (MDS) as well as a major indicator for predicting clinical course and outcome. This review concentrates on the cytogenetic classifications, the incidence and types of chromosome defects and the prognostic significance of the karyotype in adult primary MDS. Two cytogenetic classifications are currently used: one is based on the karyotype complexity (normal, single, double or complex defects), the other on clonal status (all metaphases normal, abnormal or admixture of normal and abnormal clones). Chromosome abnormalities are of both numerical and structural types. Aside from the 5q-syndrome, no specific clinico-cytogenetic entity has been reported. However, several distinct clinical and cellular features have been identified that correlate with the presence of specific chromosome defects such as inv(3)/t(3;3), +6, t(5;12), del(17p) and del(20q). The presence of complex defects is associated with reduced survival and a high risk of leukemic transformation. Among single defects, specific abnormalities may define distinct prognostic groups. Patients with del(5q) as a sole chromosome defect and a refractory anemia without excess of blasts have a favourable prognosis. For patients with trisomy 8 or monosomy 7 there may be distinct types of clinical evolution. Most patients with the 3q21q26 syndrome have a short survival. The presence of two chromosome defects may constitute an independent cytogenetic entity probably associated with relative poor prognosis. Karyotypic evolution generally represents a poor risk factor. The combination of cytogenetics with clinical and hematological features has proven to provide for a better prediction of patients' survival, leukemic transformation and response to treatment. Several scoring systems have been developed. They have to be improved by the study of new patients according to strict clinical and cytogenetic criteria and by the addition of newly recognized prognostic indicators such as histopathological features and molecular genetic mutations.

Myelodysplastic syndrome with t(5;12)(q31;p12-p13) and eosinophilia: a pediatric case with review of literature

PURPOSE

Myelodysplastic syndrome with chromosomal translocation t(5;12)(q31-33;p12-13) and eosinophilia is a new entity recently described. Nine cases have been described in adults. We report the first pediatric case with a long follow-up (7 years).

PATIENTS AND METHODS

An 8-year-old girl presented with hyperleukocytosis, eosinophilia, and no clinical symptoms. Bone marrow investigations revealed myeloid hyperplasia and clonal chromosomal translocation t(5;12)(q31;p12-13). No treatment was prescribed, but 4 years later the white blood cell count reached 144 X 10(9)/L with immature myeloid cells and splenic enlargement. Hydroxyurea chemotherapy led to a hematopoietic remission. The patient is now 16 years old and well, >7 years after the initial diagnosis.

RESULTS

The association: myelodysplastic syndrome, eosinophilia and translocation t(5;12)(q31-33;p12-13), seems to be a specific hematologic disorder. Study of cases previously reported in the literature shows the most important characteristics of this disease. However, there are still a number of questions about the disease itself (especially its treatment) and the significance of the chromosomal abnormalities.

CONCLUSION

This case seems to be the first report of the disease in a child and has had the longest follow-up. Other data should be collected to improve our knowledge of this hematopoietic disorder.

Translocation t(5;12)(q31-q33;p12-p13): a non-random translocation associated with a myeloid disorder with eosinophilia

A t(5;12)(q33;p13) translocation has been detected in two patients with myeloid disorder and eosinophilia. Six other patients with haematological disease with eosinophilia with similar translocation have been published previously. The existence of a new entity, a myeloproliferative disorder with eosinophilia and t(5;12) (q31-q33;p12-p13), is suggested by the results of the present study.