Clonal eosinophilic disorders and the hypereosinophilic syndrome

Eosinophilic mastitis mimicking a developing asymmetry

Eosinophilic mastitis is a very rare form of mastitis with few reported cases in the literature. This is a case of eosinophilic mastitis in a 48-year-old woman which presented as a screen detected right breast developing asymmetry. No sonographic abnormalities were visualized on diagnostic workup, and subsequent tomosynthesis-guided biopsy was performed. Knowledge of this rare entity is helpful in the radiologic-pathologic correlation, diagnosis, and clinical management of future cases.

A very rare case of eosinophilic mastitis

INTRODUCTION

Eosinophilic mastitis caused by eosinophil infiltration of the mammary gland is very rare. To date, no report has been published on treating patients with this disorder using anti-allergic drugs. Steroids are commonly used in these cases, but have greater burden.

PRESENTATION OF CASE

A 33-year-old woman presented to the author's clinic with a tumor and pain in the upper inner quadrant of the left breast. She underwent core needle biopsy (CNB) and was diagnosed with eosinophilic mastitis based on histopathological analysis. The serum eosinophil count at the time of biopsy increased to 1560/μL. She was administered 100 mg of suplatast tosilate (brand name: IPD capsule 100), an anti-allergic drug, 3 times daily after each meal. Thereafter, the patient's symptoms improved and her serum eosinophil count returned to normal after 4 months. To date, the patient has been recurrence-free for 3 years since the first presentation.

DISCUSSION

Organ damage induced by eosinophil infiltration was limited to the mammary gland and improved with anti-allergic drug administration.

CONCLUSION

This report presents the successful treatment of an isolated case of eosinophilic mastitis solely using anti-allergic drugs.

Systemic and Eosinophilic Lesions in Rats with Spontaneous Eosinophilia (mes Rats)

The mes rat is from an inbred mutant colony of rats with spontaneous eosinophilia. In order to investigate the pathogenesis of the mes rat, the histopathology and hematology for 76 mes rats were examined at several weeks of age. Tissue eosinophilia developed at 8 weeks of age when the blood eosinophil was 500 cells per microliter or more. Subsequently, eosinophilia progressed with age, and splenic eosinophilopoiesis and erythropoiesis appeared simultaneously. Many inflammatory lesions were induced after 10 weeks of age when the blood eosinophils became 1,000 cells per microliter or more. Gastroenteritis and mesenteric lymphadenitis were seen in 44 of 47 (94%) and 31 of 47 (66%) rats, respectively, after 10 weeks of age. Aortitis that deteriorated with age was found in 19 of 39 (49%) rats after 12 weeks of age. Hepatic fibrosis was found in four rats that exhibited severe eosinophilia and anemia. These results are comparable to the features of a hypereosinophilic syndrome in humans and other animals.

Eosinophilic cholecystitis with common bile duct stricture: a rare disease

Although the most common cause of cholecystitis is gallstones, other conditions may present as acute cholecystitis. We describe a case of eosinophilic cholecystitis with common bile duct stricture. A 36-year-old woman initially had generalised abdominal pain and peripheral eosinophilia. Diagnostic laparoscopy showed eosinophilic ascites and necrotic nodules on the posterior abdominal wall. She was treated with anthelminthics on presumption of toxacara infection based on borderline positivity of serological tests. She later presented with acute cholecystitis and had a cholecystectomy and choledocotomy. Day 9 T-tube cholangiogram showed irregular narrowing of the distal common bile duct. The patient's symptoms were improved with steroids and the T-tube was subsequently removed.

Hes1 upregulation contributes to the development of FIP1L1-PDGRA-positive leukemia in blast crisis

We have previously shown that elevated expression of Hairy enhancer of split 1 (Hes1) contributes to blast crisis transition in Bcr-Abl-positive chronic myelogenous leukemia. Here we investigate whether Hes1 is involved in the development of other myeloid neoplasms. Notably, Hes1 expression was elevated in only a few cases of 65 samples with different types of myeloid neoplasms. Interestingly, elevated expression of Hes1 was found in two of five samples of Fip1-like1 platelet-derived growth factor receptor-α (FIP1L1-PDGFA)-positive myeloid neoplasms associated with eosinophilia. Whereas FIP1L1-PDGFRα alone induced acute T-cell leukemia or myeloproliferative neoplasms in mouse bone marrow transplantation models, mice transplanted with bone marrow cells expressing both Hes1 and FIP1L1-PDGFRα developed acute leukemia characterized by an expansion of myeloid blasts and leukemic cells without eosinophilic granules. FIP1L1-PDGFRα conferred cytokine-independent growth to Hes1-transduced common myeloid progenitors, interleukin-3-dependent cells. Imatinib inhibited the growth of common myeloid progenitors expressing Hes1 with FIP1L1-PDGFRα, but not with imatinib-resistant FIP1L1-PDGFRα mutants harboring T674I or D842V. In contrast, ponatinib efficiently eradicated leukemic cells expressing Hes1 and the imatinib-resistant FLP1L1-PDGFRΑ mutant in vitro and in vivo. Thus, we have established mouse models of FIP1L1-PDGFRA-positive leukemia in myeloid blast crisis, which will help elucidate the pathogenesis of the disease and develop a new treatment for it.

Hypereosinophilia: more than meets the eye

INTRODUCTION

Eosinophilia has myriad causes and is occaisonally seen in association with malignancies. Acute myeloid leukemia presenting with eosinophilia has rarely been reported in children.

CASE

Authors herein present a case of a 5-year-old boy who presented with marked peripheral eosinophilia with symptoms of organ infiltration. Extensive work-up was needed before the diagnosis was established in this patient.

DISCUSSION

Through this case report, we want to emphasize that peripheral eosinophilia could be a dilemma challenging clinical skills and often needing vigorous perusal for the diagnosis.

Does hypereosinophilic syndrome precede common B acute lymphoblastic leukaemia in childhood? A case report

Hypereosinophilic syndrome (HES) and the association of hypereosinophilia with acute lymphoblastic leukaemia (ALL) are both rare in children. Some acute myelogenous leukaemias can present with eosinophilia, but the relationship between HES and ALL is not well known and is rarer than the relationship between HES and acute myelogenous leukaemia. Patients are diagnosed with HES when no cause is found to explain the eosinophilia leading to end organ damage. For this reason, it is recommended that patients presenting with hypereosinophilia be carefully assessed to exclude any malignant clonal proliferation. HES may present with severe clinical manifestations such as high leucocyte count, anaemia, thrombocytopaenia, hepatosplenomegaly or cardiac and neurological involvement, all of which are primarily features of myeloproliferative disorders. Some patients with HES can develop chronic eosinophilic leukaemia. Successful treatment of HES with agents used in chronic myeloid leukaemia supports the idea that HES can be a chronic myeloid disorder. There are few cases reporting an association between ALL and hypereosinophilia that precedes or is concomitant with ALL. Here we report the case of a 14-year-old girl who developed common B ALL 7 months after diagnosis and treatment of HES. Interestingly, eosinophilia was not concomitant with the diagnosis of ALL.

Eosinophilic Variant of Chronic Myeloid Leukemia with Vascular Complications

Eosinophilic variant of CML (eoCML) is a unique disease with a poor prognosis. Like the hypereosinophilic syndrome (HES), eoCML has no clinically identifiable reason for an increased eosinophil count in the peripheral blood. In contrast to HES, eoCML patients carry a distinct chromosomal abnormality. The bcr/abl fusion gene (Philadelphia chromosome) is the genetic basis of this clonal disease. Recently, eoCML has been separated from HES. Patients with eoCML frequently suffer organ damage including the heart and lungs. This damage is related to the release of eosinophilic granules in the blood, which results in fibrosis of the endothelial lining. We report a case of a peripheral vasculitis complicated by gangrene of the fingers in a patient with eoCML. Despite an almost complete response to CML treatment with Gleevac, combined with prednisone, aspirin and coumadin the patient sustained irreversible damage to the vascular lining of the distal arteries of the upper extremities.

Guidelines for an integrated diagnostic approach of chronic lymphoproliferative disorders in the routine laboratory of haematology in Belgium

This paper summarizes the minimal workout of chronic lymphoproliferative disorders in a routine laboratory of haematology as recommended by a team of experienced laboratory supervisors in Belgium, taking into account the specific organisation of healthcare in Belgium, the innovations in the field of molecular analyses and related reimbursement. The starting point was essentially based upon clinical and/or haematological indications and it is emphasized that conclusions should be drawn in close dialogue with the clinician and experts in cytogenetics and histopathology. Reports made in the laboratory should be based upon an integration of cytomorphological, immunophenotypical and molecular data. These guidelines are not intended to be used as universal 'diagnostic pathways', but should be useful in developing local diagnostic pathways. It is well understood that this consensus, being valid anno 2009, may rapidly change with new technologies being introduced and new targets discovered.

[Incidence and causes of hypereosinophilia (corrected) in the patients of a university hospital]

BACKGROUND

Eosinophilia may be associated with various primary and reactive conditions. The incidence and the causes of eosinophilia might have been changed according to the changes in the incidence of diseases such as cancer, chronic degenerative diseases, etc. We have conducted a retrospective study to investigate the incidence and causes of eosinophilia.

METHODS

Eosinophilia and hypereosinophilia were defined when absolute eosinophil count was greater than 500/microL and 1,500/microL, respectively. Patient's clinical records were reviewed to find out the underlying clinical conditions responsible for causes of hypereosinophilia. Conventional chromosomal analysis, reverse transcriptase PCR and FISH for gene rearrangement were performed to check the presence of clonal eosinophilia.

RESULTS

Out of 41,137 patients who had a hematology profile performed, 5,019 (12.2%) and 373 patients (0.9%) were found to have eosinophilia and hypereosinophilia, respectively. Among patients with hypereosinophilia, 227 patients (60.9%) had identifiable and/or possible causes. The major causes of hypereosinophilia were malignancy (35.2%), allergy and skin diseases (18.1%), infectious diseases (15.4%), hepatobiliary diseases (7.5%), bone marrow clonal diseases (6.6%) and parasite infections (6.6%). We also found a rare case of FIP1L1-PDGFRalpha positive chronic eosinophilic leukemia combined with light chain multiple myeloma.

CONCLUSIONS

We found a difference in the distribution of causes of hypereosinophilia in comparison with previous Korean studies, and the most common cause of hypereosinophilia in the current study was malignancy. A rare case of clonal eosinophilia (chronic eosinophilic leukemia) associated with multiple myeloma was confirmed using molecular studies.

Eosinophilic leukaemia in a cat

A 14-year-old female domestic shorthair cat was presented to Tehran University Veterinary Teaching Hospital for a persistent fever, anorexia, intermittent vomiting, weight loss and weakness. The main clinical signs were pale mucous membranes, dehydration and splenomegaly. The complete blood count and serum biochemistry tests revealed non-regenerative anaemia, thrombocytopenia and increased alkaline phosphatase (ALP) activity. An enzyme-linked immunosorbent assay (ELISA) test for feline leukaemia virus was negative. Blood film and bone marrow examination revealed a large number of immature eosinophils with variable sizes and numbers of faintly azurophilic granules. Cytochemical staining of blood film demonstrated 70% positive cells for ALP activity. Four percent CD34 positive cells were detected by flow cytometry. As eosinophilic leukaemia is difficult to identify by light microscopy, well-defined diagnostic criteria and the use of flow cytometry and cytochemical staining can improve the ability to correctly diagnose this type of leukaemia in cats.

Expressions of the VLA-4, LFA-1 and Mac-1 integrins in eosinophil migration in a case of chronic eosinophilic leukaemia

Migration of eosinophil (Eo) into tissues is a hallmark of chronic eosinophilic leukaemia (CEL), but the exact mechanism involved in cell migration is unknown. We report on a patient with CEL who presented high expressions of VLA-4, LFA-1 and Mac-1 integrins on the Eo surface, increased chemotaxis of Eo to eotaxin, decreased chemotaxis of Eo after inhibition of the cyclic guanosine monophosphate (cGMP), and a high level of intracellular cGMP. These findings suggest that an upregulation of expression of these integrins on Eo surface and a high intracellular level of cGMP may be involved in the increased Eo migration observed in our CEL patient. However, the definitive roles of these molecules in the proliferation and migration of Eo in CEL disease require wider confirmation by analysis of additional patients with the disease.

Eosinophilia: secondary, clonal and idiopathic

Blood eosinophilia signifies either a cytokine-mediated reactive phenomenon (secondary) or an integral phenotype of an underlying haematological neoplasm (primary). Secondary eosinophilia is usually associated with parasitosis in Third World countries and allergic conditions in the West. Primary eosinophilia is operationally classified as being clonal or idiopathic, depending on the respective presence or absence of a molecular, cytogenetic or histological evidence for a myeloid malignancy. The current communication features a comprehensive clinical summary of both secondary and primary eosinophilic disorders with emphasis on recent developments in molecular pathogenesis and treatment.

The FIP1L1-PDGFRA fusion gene cooperates with IL-5 to induce murine hypereosinophilic syndrome (HES)/chronic eosinophilic leukemia (CEL)-like disease

Dysregulated tyrosine kinase activity by the Fip1-like1 (FIP1L1)-platelet-derived growth factor receptor alpha (PDGFRA) (F/P) fusion gene has been identified as a cause of clonal hypereosinophilic syndrome (HES), called F/P-positive chronic eosinophilic leukemia (CEL) in humans. However, transplantation of F/P-transduced hematopoietic stem cells/progenitors (F/P(+) HSCs/Ps) into mice results in a chronic myelogenous leukemia-like disease, which does not resemble HES. Because a subgroup of patients with HES show T-cell-dependent interleukin-5 (IL-5) overexpression, we determined if expression of the F/P fusion gene in the presence of transgenic T-cell IL-5 overexpression in mice induces HES-like disease. Mice that received a transplant of CD2-IL-5-transgenic F/P(+) HSC/Ps (IL-5Tg-F/P) developed intense leukocytosis, strikingly high eosinophilia, and eosinophilic infiltration of nonhematopoietic as well as hematopoietic tissues, a phenotype resembling human HES. The disease phenotype was transferable to secondary transplant recipients of a high cell dose, suggesting involvement of a short-term repopulating stem cell or an early myeloid progenitor. Induction of significant eosinophilia was specific for F/P since expression of another fusion oncogene, p210-BCR/ABL, in the presence of IL-5 overexpression was characterized by a significantly lower eosinophilia than IL-5Tg-F/P recipients. These results suggest that F/P is not sufficient to induce a HES/CEL-like disease but requires a second event associated with IL-5 overexpression.

Imatinib mesylate as a novel treatment option for hypereosinophilic syndrome: two case reports and a comprehensive review of the literature

Hypereosinophilic syndromes (HES) are a heterogenous group of rare disorders characterized by sustained and otherwise unexplained overproduction of eosinophils with organ involvement and consecutive dysfunction. Recent reports document the efficacy of imatinib mesylate in a large proportion of HES patients (65%). Rearrangements involving the platelet-derived growth factor receptor genes (PDGFRA and PDGFRB), both tyrosine kinase receptors, have been demonstrated to be pathogenetically linked to the dysregulated clonal overproduction of eosinophils. This refined hypothesis has been confirmed by the discovery of the novel FIP1L1-PDGFRA fusion gene, which is a gain-of-function gene on chromosome 4q12. Its product is an imatinib-sensitive tyrosine kinase, which can be found in a subset of patients with HES, particularly in those responding to treatment with imatinib mesylate. Here, we sum up recent knowledge of clinical features, pathophysiology and novel treatment aspects of HES by performing a comprehensive search of the available literature and report on 94 patients. We particularly address the issue of organ involvement and specific characteristics of the variable clinical pictures. In addition, two cases will be presented, which illustrate typical clinical scenarios and treatment outcome.

Eosinophilic pneumonias

Eosinophilic pneumonias (EP) encompass a wide spectrum of lung diseases characterized by peripheral blood eosinophilia (>1 x 10(9) eosinophils/l) and/or alveolar eosinophilia (>25%). Blood eosinophilia may be lacking, as in the early phase of idiopathic acute EP, or in patients already taking oral corticosteroids. EP may present with varying severity, ranging from almost asymptomatic infiltrates to the acute respiratory distress syndrome necessitating mechanical ventilation. Possible causes of EP must be thoroughly investigated, especially drugs and the variety of parasitic infections (considering history of travel or residence in areas of endemic parasitic infection). However, chronic EP remains idiopathic in many cases. When present, extrathoracic manifestations lead to suspect Churg-Strauss syndrome (CSS) or the hypereosinophilic syndrome (HES), the prognosis of which is dominated by cardiac involvement. Apart from the treatment of specific causes when possible, corticosteroids remain the cornerstone of symptomatic treatment for eosinophilic disorders, usually with a dramatic response, but frequent relapses when tapering or after stopping the treatment. The adjunction of immunosuppressants to corticosteroids is necessary in patients with CSS and poor prognosis factors. Imatinib has recently proven effective in the treatment of the myeloproliferative variant of the HES.

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.

Neuropatia periférica e miosite na síndrome hipereosinofílica idiopática: relato de caso

Descrevemos um caso de síndrome hipereosinofílica idiopática, com manifestações clínicas de neuropatia periférica e sinais de miosite inflamatória. Trata-se de mulher de 20 anos de idade, que apresentou dificuldade progressiva para caminhar com quedas freqüentes e edema de membros inferiores até o nível do joelho, associado a parestesias e cãibras. O exame neurológico revelou hipotonia, arreflexia e redução da força e sensibilidade nos membros inferiores. O exame parasitológico de fezes foi negativo e o hemograma mostrou 24 % de eosinófilos (1848/mm³). Estudo eletrodiagnóstico mostrou comprometimento axonal sensitivo-motor nos nervos dos membros inferiores. A biópsia muscular mostrou discreta reação inflamatória perivascular e intersticial. Tratada com prednisona a paciente apresentou remissão dos sintomas em dois meses.

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.

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.

Eosinophilic leukemia associated with t(2;5)(p23;q31)

Chromosomal aberrations have been reported in most malignant hematopoietic disorders such as acute or chronic myeloid leukemia, acute lymphoid leukemia, and myelodysplastic syndromes. Eosinophilic leukemia is a rare hematologic malignancy difficult to distinguish from other forms of idiopathic hypereosinophilic syndrome, so that the diagnosis is often made by exclusion, unless cytogenetic abnormalities can be demonstrated in bone marrow cells. We describe a patient with eosinophilic leukemia whose cytogenetic study shows a t(2;5)(p23;q31). Initial data could suggest a clonal eosinophilia, with an hepatosplenomegaly, severe pancytopenia, and a high level of blood and medullar eosinophilia.

Allogeneic peripheral blood cell transplantation for hypereosinophilic syndrome with myelofibrosis

Patients with hypereosinophilic syndrome (HES) display a very heterogeneous clinical picture ranging from asymptomatic cases to very aggressive forms. We report a 38-year-old woman with progressive HES who developed severe myelofibrosis and was treated by allogeneic stem cell transplantation, using peripheral blood (PBSCT) instead of bone marrow as the source of progenitor cells, after conditioning with cytoxan and busulphan. To the best of our knowledge, this is the first case of HES with myelofibrosis treated with PBSCT. The patient remains alive 8 months post-PBSCT, and bone marrow fibrosis has significantly decreased following transplantation. Bone Marrow Transplantation (2000) 25, 217-218.

The role of thymus-dependent T cells in hexachlorobenzene-induced inflammatory skin and lung lesions

The involvement of thymus-dependent T cells in the inflammatory skin and lung lesions and spleen effects induced by hexachlorobenzene (HCB) was investigated by using genetically athymic and euthymic WAG/Rij rats and Brown Norway (BN) rats with or without depletion of T cells by adult thymectomy, lethal irradiation, and bone marrow reconstitution. Rats were exposed to diets with no supplementation or diets supplemented with 150 or 450 mg HCB per kg diet for 4 (BN) or 6 (WAG/Rij) weeks. Skin lesion development and body weight gains were assessed during exposure and spleen and liver weights as well as histopathologic changes in skin, lung, and spleen were assessed after exposure. Oral HCB exposure of athymic and euthymic rats of both rat strains resulted in a dose-dependent increase of relative liver weight at doses of 150 and 450 mg/kg HCB and increased relative spleen weights at a dose of 450 mg/kg. HCB exposure of both strains further resulted in inflammatory changes in skin, lungs, and splenic red pulp independent of the T cell status except for skin lesions in the BN strain. HCB-exposed T cell-competent BN rats showed faster skin lesion development than the T cell-depleted rats, although qualitatively and quantitatively similar skin pathology was observed at the end of the 4-week exposure in both groups. In the WAG/Rij strain skin lesions could not be comparatively assessed due to preexistent inflammatory skin pathology in the nude rats. This study showed that thymus-derived T cells are not required for the induction of skin and lung pathology and splenic changes by HCB and therefore it is suggested that HCB acts differently from many allergenic and autoimmunogenic low molecular weight compounds that trigger pathology via thymus-dependent mechanisms. A role for mononuclear phagocytes and, in BN rats, eosinophilic granulocytes, in the HCB-induced pathology is suggested since these cells were prominently present in the HCB-induced lesions.

Clonality of Isolated Eosinophils in the Hypereosinophilic Syndrome

The idiopathic hypereosinophilic syndrome (IHES) is a rare disorder characterized by unexplained, persistent eosinophilia associated with multiple organ dysfunction due to eosinophilic tissue infiltration. In the absence of karyotypic abnormalities, there is no specific test to detect clonal eosinophilia in IHES. Analysis of X-chromosome inactivation patterns can be used to determine whether proliferative disorders are clonal in origin. Methylation of HpaII andHha I sites near the polymorphic trinucleotide repeat of the human androgen receptor gene (HUMARA) has been shown to correlate with X-inactivation. In this study, we have used the polymerase chain reaction (PCR) with nested primers to analyze X-inactivation patterns of the HUMARA loci in purified eosinophils from female patients with eosinophilia. Peripheral blood eosinophils were isolated by their autofluoresence using flow cytometric sorting. Eosinophils purified from a female patient presenting with IHES were found to show a clonal pattern of X-inactivation. Eosinophil-depleted leukocytes from this patient were polyclonal by HUMARA analysis, thus excluding skewedness of random X-inactivation. After corticosteroid suppression of her blood eosinophilia, a clonal population of eosinophils could no longer be detected in purified eosinophils. In contrast, eosinophils purified from a patient with Churg-Strauss syndrome and from six patients with reactive eosinophilias attributed to allergy, parasitic infection, or drug reaction showed a polyclonal pattern of X-inactivation by HUMARA analysis. The finding of clonal eosinophilia in a patient presenting with IHES indicates that such patients may have, in reality, a low-grade clonal disorder that can be distinguished from reactive eosinophilias by HUMARA analysis. Further, the method described can be used to monitor disease progression.

Clonality of Isolated Eosinophils in the Hypereosinophilic Syndrome

The idiopathic hypereosinophilic syndrome (IHES) is a rare disorder characterized by unexplained, persistent eosinophilia associated with multiple organ dysfunction due to eosinophilic tissue infiltration. In the absence of karyotypic abnormalities, there is no specific test to detect clonal eosinophilia in IHES. Analysis of X-chromosome inactivation patterns can be used to determine whether proliferative disorders are clonal in origin. Methylation of HpaII andHha I sites near the polymorphic trinucleotide repeat of the human androgen receptor gene (HUMARA) has been shown to correlate with X-inactivation. In this study, we have used the polymerase chain reaction (PCR) with nested primers to analyze X-inactivation patterns of the HUMARA loci in purified eosinophils from female patients with eosinophilia. Peripheral blood eosinophils were isolated by their autofluoresence using flow cytometric sorting. Eosinophils purified from a female patient presenting with IHES were found to show a clonal pattern of X-inactivation. Eosinophil-depleted leukocytes from this patient were polyclonal by HUMARA analysis, thus excluding skewedness of random X-inactivation. After corticosteroid suppression of her blood eosinophilia, a clonal population of eosinophils could no longer be detected in purified eosinophils. In contrast, eosinophils purified from a patient with Churg-Strauss syndrome and from six patients with reactive eosinophilias attributed to allergy, parasitic infection, or drug reaction showed a polyclonal pattern of X-inactivation by HUMARA analysis. The finding of clonal eosinophilia in a patient presenting with IHES indicates that such patients may have, in reality, a low-grade clonal disorder that can be distinguished from reactive eosinophilias by HUMARA analysis. Further, the method described can be used to monitor disease progression.