Chronic eosinophilic leukaemia presenting with erythroderma, mild eosinophilia and hyper-IgE: clinical, immunological and cytogenetic features and therapeutic approach. A case report

Chronic myeloid leukemia: a type of MPN

This review article classifies chronic myeloid leukemia (CML) based on cytogenetic analyses and different mutations detected in CML patients. The use of advanced technologies, such as karyotyping, fluorescent in situ hybridization, and comparative genomic hybridization, has allowed us to study CML in detail and observe the different biochemical changes that occur in different CML types. This review also highlights the different types of receptor and signaling pathway mutations that occur in CML.

Eosinophilic myeloproliferative disorders

Despite recent attempts to define and classify patients with marked eosinophilia and features consistent with myeloproliferative disease, areas of controversy remain. These are particularly apparent in situations in which multiple lineages are involved in a clonal process and clinical manifestations are overlapping. Although the introduction of new molecular diagnostics and targeted therapies has begun to clarify the boundaries between some of these disorders, several questions remain with respect to the classification of patients with myeloproliferative hypereosinophilic syndrome (HES) of unknown etiology.

The hypereosinophilic syndromes: current concepts and treatments

The hypereosinophilic syndromes (HES) encompass a spectrum of diseases that have increased blood eosinophils and tissue damage in common. The clinical manifestations are protean and may involve any organ system, but especially the skin. Our understanding of these diseases has drastically changed over the past 15 years, along with new classifications that characterize patients with marked eosinophilia. One HES variant, myeloproliferative, is actually chronic eosinophilic leukaemia with a unique genetic marker, FIP1L1-PDGFRA. Such patients are well-controlled by administration of the kinase inhibitor, imatinib, and remissions appear durable with continued imatinib therapy. FIP1L1-PDGFRA is expressed in several cell lineages, thus explaining increases in neutrophils and mast cells in HES. The lymphocytic HES variant is associated with T-cell clones producing interleukin-5 (IL-5) and can evolve into lymphoma. While myeloproliferative and lymphocytic HES are well established and permit elimination of the term, idiopathic, to these varieties, most HES patients do not fall into these categories and are classified as complex (using the 2006 Workshop Report). A recent study showed that a monoclonal antibody to IL-5, mepolizumab, reduced glucocorticoid therapy in HES patients who did not possess the FIP1L1-PDGFRA mutation while controlling eosinophilia and preventing recurrence or progression of tissue damage. These advances augur well for continued progress in the understanding and treatment of HES.

Chronic eosinophilic leukemia: a case report and review of literature

Chronic Eosinophilic Leukemia (CEL) is a rare type of chronic myeloproliferative disorder of unknown etiology with no available true incidence. The vaguely overlapping clinico - pathological picture of CEL with idiopathic hypereosinophilic syndrome (IHES) often adds to the diagnostic confusion. An evidence of genetic clonality of eosinophils or an increase in blast cells in the blood or bone marrow is mandatory for diagnosis of CEL while no specific diagnostic tests exist for IHES; making it an entity of exclusion. Till date, CEL is a rarely reported entity in India. We add yet another case of eosinophilic leukemia along with review of available literature.

Treatment of hypereosinophilic syndromes with prednisone, hydroxyurea, and interferon

The hypereosinophilic syndromes continue to challenge our clinical acumen and skills. Prednisone, hydroxyurea, and interferon alpha 2b are three of the oldest agents that allow control of eosinophilia and its devastating clinical consequences. They still work. As our experience with them has grown, it has become evident that use of these agents in combination will control eosinophilia in most patients. Moreover, with time, the doses can frequently be reduced. Even with the advent of newer agents for treatment of hypereosinophilic syndromes, these three medications still afford an excellent, cost-effective avenue for disease management.

Advances in molecular diagnostics of myeloproliferative disorders

Incremental advances in the molecular pathogenesis of myeloproliferative disorders (MPDs) have had a substantial impact on clinical practice in terms of both diagnosis and treatment. An array of novel molecular methods are being developed and integrated into the current battery of tests for diagnosis and monitoring of treatment response. Primarily, subjective clinico-histologic approaches to diagnosis are being replaced by more objective semimolecular diagnostic algorithms. Furthermore, identification of disease-specific molecular markers has facilitated the development of small-molecule drugs for targeted therapy. This review provides an overview of MPDs with emphasis on molecular diagnostic tests and their incorporation into contemporary diagnostic and therapeutic algorithms.

The diagnostic interface between histology and molecular tests in myeloproliferative disorders

PURPOSE OF REVIEW

The sighting of the Philadelphia chromosome in 1960, later shown to harbor the BCR-ABL mutation in chronic myeloid leukemia, is arguably the most seminal contribution to molecular oncology. In the decades that followed, other cytogenetic and molecular disease markers have been described and effectively incorporated into routine diagnostic tests. This review discusses how this process is unfolding in myeloproliferative disorders.

RECENT FINDINGS

In 2003, a karyotypically-occult FIP1L1-PDGFRA was reported in a subset of patients with blood eosinophilia and bone marrow mastocytosis; this mutation has since joined several other molecular markers for eosinophilic (e.g. PDGFRbeta- and FGFR1-rearrangements) and mast cell (e.g. KITD816V) disorders. In 2005, JAK2V617F was described in polycythemia vera and other BCR-ABL myeloproliferative disorders; the particular discovery has already had a major impact on current diagnostic approaches in polycythemia vera. These remarkable molecular discoveries are both redefining and reinforcing the diagnostic role of bone marrow histopathology.

SUMMARY

Recent progress in the molecular pathogenesis of myeloproliferative disorders calls for a paradigm shift in traditional diagnostics, which is based on subjective technologies or assignment to a 'consensus'-based ever-changing list of inclusionary and exclusionary criteria. Routine clinical practice might be better served by diagnostic algorithms that incorporate molecular disease markers, which complement histological impression.

Classification of chronic myeloid disorders: From Dameshek towards a semi-molecular system

Hematological malignancies are phenotypically organized into lymphoid and myeloid disorders, although such a distinction might not be precise from the standpoint of lineage clonality. In turn, myeloid malignancies are broadly categorized into either acute myeloid leukemia (AML) or chronic myeloid disorder (CMD), depending on the presence or absence, respectively, of AML-defining cytomorphologic and cytogenetic features. The CMD are traditionally classified by their morphologic appearances into discrete clinicopathologic entities based primarily on subjective technologies. It has now become evident that most CMD represent clonal stem cell processes where the primary oncogenic event has been characterized in certain instances; Bcr/Abl in chronic myeloid leukemia, FIP1L1-PDGFRA or c-kit(D816V) in systemic mastocytosis, rearrangements of PDGFRB in chronic eosinophilic leukemia, and rearrangements of FGFR1 in stem cell leukemia/lymphoma syndrome. In addition, Bcr/Abl-negative classic myeloproliferative disorders are characterized by recurrent JAK2(V617F) mutations, whereas other mutations affecting the RAS signaling pathway molecules have been associated with juvenile myelomonocytic leukemia. Such progress is paving the way for a transition from a histologic to a semi-molecular classification system that preserves conventional terminology, while incorporating new information on molecular pathogenesis.

Atypical myeloproliferative disorders: diagnosis and management

Myeloid disorders constitute a subgroup of hematological malignancies that is separate from lymphoid disorders. The World Health Organization system for classification of tumors of the hematopoietic system divides myeloid disorders into acute myeloid leukemia and chronic myeloid disorders based on the presence or absence, respectively, of acute myeloid leukemia--defining morphological and cytogenetic features including the presence of 20% or more myeloblasts in either the bone marrow or the peripheral blood. A recently proposed semimolecular classification system for chronic myeloid disorders recognizes 3 broad categories: the myelodysplastic syndrome, classic myeloproliferative disorders (MPD), and atypical MPD. Classic MPD includes polycythemia vera, essential thrombocythemia, myelofibrosis with myeloid metaplasia, and chronic myeloid leukemia. Both myelodysplastic syndrome and BCR/ABL-negative classic MPD were previously discussed as part of the current ongoing symposium on hematological malignancies. The current review focuses on the diagnosis and treatment of both molecularly defined and clinicopathologically assigned categories of atypical MPD: chronic myelomonocytic leukemia, juvenile myelomonocytic leukemia, chronic neutrophilic leukemia, chronic basophilic leukemia, chronic eosinophilic leukemia, idiopathic eosinophilia including hypereosinophilic syndrome, systemic mastocytosis, unclassified MPD, and eosinophilic/mast cell disorders associated with mutations of platelet-derived growth factor receptors alpha (PDGFRA) and beta (PDGFRB), FGFR1, and KIT.

The JAK2V617F tyrosine kinase mutation in myeloproliferative disorders: status report and immediate implications for disease classification and diagnosis

Janus kinase 2 (JAK2) is a cytoplasmic protein-tyrosine kinase that catalyzes the transfer of the gamma-phosphate group of adenosine triphosphate to the hydroxyl groups of specific tyrosine residues in signal transduction molecules. JAK2 mediates signaling downstream of cytokine receptors after ligand-induced autophosphorylation of both receptor and enzyme. The main downstream effectors of JAK2 are a family of transcription factors known as signal transducers and activators of transcription (STAT) proteins. The myeloproliferative disorders (MPD), a subgroup of myeloid malignancies, are clonal stem cell diseases characterized by an expansion of morphologically mature granulocyte, erythroid, megakaryocyte, or monocyte lineage cells. Among the traditionally classified MPD, the disease-causing mutation has been delineated, thus far, for only chronic myeloid leukemia (ie, bcr/abl). In the past 3 months, 7 different studies have Independently described a close association between an activating JAK2 mutation (JAK2V617F) and the classic bcr/abi-negative MPD (ie, polycythemia vera, essential thrombocythemia, myelofibrosis with myeloid metaplasia) as well as the less frequent occurrence of the same mutation in both atypical MPD and the myelodysplastic syndrome. The particular finding is consistent with previous observations that have implicated the JAK/STAT signal transduction pathway in the pathogenesis of bcr/abl-negative MPD, Including the phenotype of growth factor independence and/or hypersensitivity. The current article summarizes this new information and discusses its implications for both classification and diagnosis of MPD.

Life-threatening erythroderma: diagnosing and treating the “red man”

Exfoliative erythroderma, or diffuse erythema and scaling of the skin, may be the morphologic presentation of a variety of cutaneous and systemic diseases. Establishing the diagnosis of the underlying disease is often difficult and, not uncommonly, erythroderma is classified as idiopathic. Several cases are presented to demonstrate the diversity of presentation of this disease. Laboratory findings are typically unhelpful in establishing the etiology of erythroderma. Clinical data combined with multiple skin biopsies over time are necessary. Systemic complications of erythroderma include infection, fluid and electrolyte imbalances, thermoregulatory disturbance, high output cardiac failure, and acute respiratory distress syndrome. The initial approach to the management of erythroderma of any etiology includes attention to nutrition, fluid and electrolyte replacement, and the institution of gentle local skin care measures. Oatmeal baths and wet dressings to weeping or crusted sites should be followed by application of bland emollients and low-potency topical corticosteroids. Systemic dermatologic therapy may be required to maintain improvement achieved with local measures or to control erythroderma refractory to local measures. The prognosis of erythroderma is dependent on the underlying etiology.

Blood eosinophilia: a new paradigm in disease classification, diagnosis, and treatment

Acquired blood eosinophilia is considered either a primary or a secondary phenomenon. Causes of secondary (ie, reactive) eosinophilia include tissue-invasive parasitosis, allergic or inflammatory conditions, and malignancies in which eosinophils are not considered part of the neoplastic process. Primary eosinophilia is classified operationally into 2 categories: clonal and idiopathic. Clonal eosinophilia stipulates the presence of either cytogenetic evidence or bone marrow histological evidence of an otherwise classified hematologic malignancy such as acute leukemia or a chronic myeloid disorder. Idiopathic eosinophilia is a diagnosis of exclusion (ie, not secondary or clonal). Hypereosinophilic syndrome is a subcategory of idiopathic eosinophilia; diagnosis requires documentation of both sustained eosinophilia (absolute eosinophil count > or = 1500 cells/microL for at least 6 months) and target organ damage (eg, involvement of the heart, lung, skin, or nerve tissue). Genetic mutations involving the platelet-derived growth factor receptor genes (PDGFR-alpha and PDGFR-beta) have been pathogenetically linked to clonal eosinophilia, and their presence predicts treatment response to imatinib. Accordingly, cytogenetic and/or molecular investigations for the presence of an imatinib-sensitive molecular target should accompany current evaluation for primary eosinophilia. In the absence of such a drug target, specific treatment is dictated by the underlying hematologic malignancy in cases of clonal eosinophilia; however, the initial treatment of choice for symptomatic patients with hypereosinophilic syndrome is prednisone and/or interferon alfa.

Modern diagnosis and treatment of primary eosinophilia

The recent discovery of an eosinophilia-specific, imatinib-sensitive, karyotypically occult but fluorescence in situ hybridization-apparent molecular lesion in a subset of patients with blood eosinophilia has transformed the diagnostic as well as treatment approach to eosinophilic disorders. Primary (i.e. nonreactive) eosinophilia is considered either "clonal" or "idiopathic" based on the presence or absence, respectively, of either a molecular or bone marrow histological evidence for a myeloid neoplasm. Clonal eosinophilia might accompany a spectrum of clinicopathological entities, the minority of whom are molecularly characterized; Fip1-like-1-platelet-derived growth factor receptor alpha (FIP1L1-PDGFRA(+)) systemic mastocytosis, platelet-derived growth factor receptor beta (PDGFRB)-rearranged atypical myeloproliferative disorder, chronic myeloid leukemia, and the 8p11 syndrome that is associated with fibroblast growth factor receptor 1 (FGFR1) rearrangement. Hypereosinophilic syndrome (HES) is a subcategory of idiopathic eosinophilia and is characterized by an absolute eosinophil count of > or =1.5 x 10(9)/l for at least 6 months as well as eosinophil-mediated tissue damage. At present, a working diagnosis of primary eosinophilia mandates a bone marrow examination, karyotype analysis, and additional molecular studies in order to provide the patient with accurate prognostic information as well as select appropriate therapy. For example, the presence of either PDGFRA or PDGFRB mutations warrants the use of imatinib in clonal eosinophilia. In HES, prednisone, hydroxyurea, and interferon-alpha constitute first-line therapy, whereas imatinib, cladribine, and monoclonal antibodies to either interleukin-5 (mepolizumab) or CD52 (alemtuzumab) are considered investigational. Allogeneic transplantation offers a viable treatment option for drug-refractory cases.

Interferon treatment for hypereosinophilic syndromes and systemic mastocytosis

Hypereosinophilic syndromes (HES) and systemic mastocytosis (SMCD) are heterogeneous disorders with clinical symptoms from local and remote effects of excessive proliferation of eosinophils and mast cells, respectively. Interferon alpha (IFN-alpha), alone or in combination with other medications, can be a useful, and at times life-saving, treatment for patients with HES. Receptors for IFN-alpha are present on eosinophils, and clinical benefits are due to its effect on eosinophil proliferation, migration, activation, and survival. These effects are likely mediated through multiple pathways including, but not limited to, inhibition of eosinophil colony-forming cells, upregulation of IFN-gamma synthesis, and inhibition of production of eosinophil-active cytokines by T cells, mast cells, and mononuclear cells. IFN-alpha has been life-saving for patients with intractable HES that were resistant to prednisone, hydroxyurea, and other agents. Resistance to the eosinopenic effect of IFN-alpha does not develop and the dose of IFN-alpha necessary to maintain control of eosinophilia often decreases with time. The combination of IFN-alpha and hydroxyurea is very useful and allows dosage reduction of IFN-alpha and better control of hypereosinophilia than with either agent alone. The efficacy of IFN-alpha for treatment of SMCD has been more difficult to establish, with both favorable and unfavorable results reported. The disparate results may have resulted from the small number of patients with SMCD treated with IFN-alpha, the use of various criteria for a "successful" treatment outcome, short duration of treatment and follow-up, and the use of modest dosages. In reported series, side effects from IFN-alpha have frequently been dose-limiting. IFN-alpha improves many of the clinical symptoms of SMCD including dermatological, hematological, gastrointestinal, and systemic symptoms associated with histamine release. IFN-alpha has a beneficial effect on skeletal symptoms because of its ability to increase bone density and reduce painful episodes from vertebral fractures. No consistent improvement in bone marrow infiltration by mast cells has been demonstrated except in a recent study employing high dosages of IFN-alpha. A beneficial effect from the combination of IFN-alpha and prednisone has been reported for several patients, suggesting that combined use of these two medications may provide synergism in treatment outcomes.

Blood eosinophilia: a new paradigm in disease classification, diagnosis, and treatment

Acquired blood eosinophilia is considered either a primary or a secondary phenomenon. Causes of secondary (ie, reactive) eosinophilia include tissue-invasive parasitosis, allergic or inflammatory conditions, and malignancies in which eosinophils are not considered part of the neoplastic process. Primary eosinophilia is classified operationally into 2 categories: clonal and idiopathic. Clonal eosinophilia stipulates the presence of either cytogenetic evidence or bone marrow histological evidence of an otherwise classified hematologic malignancy such as acute leukemia or a chronic myeloid disorder. Idiopathic eosinophilia is a diagnosis of exclusion (ie, not secondary or clonal). Hypereosinophilic syndrome is a subcategory of idiopathic eosinophilia; diagnosis requires documentation of both sustained eosinophilia (absolute eosinophil count > or = 1500 cells/microL for at least 6 months) and target organ damage (eg, involvement of the heart, lung, skin, or nerve tissue). Genetic mutations involving the platelet-derived growth factor receptor genes (PDGFR-alpha and PDGFR-beta) have been pathogenetically linked to clonal eosinophilia, and their presence predicts treatment response to imatinib. Accordingly, cytogenetic and/or molecular investigations for the presence of an imatinib-sensitive molecular target should accompany current evaluation for primary eosinophilia. In the absence of such a drug target, specific treatment is dictated by the underlying hematologic malignancy in cases of clonal eosinophilia; however, the initial treatment of choice for symptomatic patients with hypereosinophilic syndrome is prednisone and/or interferon alfa.

Imatinib Therapy in Clonal Eosinophilic Disorders, Including Systemic Mastocytosis

Primary (nonreactive) eosinophilia is operationally classified as either a "clonal" or an "idiopathic" process. Clonal eosinophilia stipulates the presence of cytogenetic, molecular, or bone marrow histologic evidence of acute leukemia or a chronic myeloid disorder. Idiopathic eosinophilia is a diagnosis of exclusion that is made after ruling out both "secondary" (reactive) and clonal eosinophilia. Hypereosinophilic syndrome is a subclass of idiopathic eosinophilia that requires the documentation of both sustained eosinophilia (> or = 1500/microL for at least 6 months) and target-organ damage. A series of novel observations in the last 5 years have warranted a refined approach to the diagnosis as well as the treatment of clonal eosinophilic disorders, including systemic mastocytosis. At the center of these new developments are mutations involving the platelet-derived growth factor receptor genes (PDGFRA and PDGFRB), which have been pathogenetically linked to clonal eosinophilia, and their presence predicts complete as well as durable treatment responses to imatinib mesylate. The bone marrow histologic phenotype of these imatinib-sensitive eosinophilic disorders includes systemic mastocytosis, chronic eosinophilic leukemia, chronic myelomonocytic leukemia, and atypical chronic myeloproliferative disorder.

Imatinib targets other than bcr/abl and their clinical relevance in myeloid disorders

Imatinib mesylate is a small molecule drug that in vitro inhibits the Abelson (Abl), Arg (abl-related gene), stem cell factor receptor (Kit), and platelet-derived growth factor receptor A and B (PDGFRA and PDGFRB) tyrosine kinases. The drug has acquired therapeutic relevance because of similar inhibitory activity against certain activating mutations of these molecular targets. The archetypical disease in this regard is chronic myeloid leukemia, where abl is constitutively activated by fusion with the bcr gene (bcr/abl). Similarly, the drug has now been shown to display equally impressive therapeutic activity in eosinophilia-associated chronic myeloproliferative disorders that are characterized by activating mutations of either the PDGFRB or the PDGFRA gene. The former usually results from translocations involving chromosome 5q31-33, and the latter usually results from an interstitial deletion involving chromosome 4q12 (FIP1L1-PDGFRA). In contrast, imatinib is ineffective, in vitro and in vivo, against the mastocytosis-associated c-kit D816V mutation. However, wild-type and other c-kit mutations might be vulnerable to the drug, as has been the case in gastrointestinal stomal cell tumors. Imatinib is considered investigational for the treatment of hematologic malignancies without a defined molecular drug target, such as polycythemia vera, myelofibrosis with myeloid metaplasia, and acute myeloid leukemia.

Myeloproliferative disorders with translocations of chromosome 5q31-35: role of the platelet-derived growth factor receptor Beta

Acquired reciprocal chromosomal translocations that involve chromosome bands 5q31-33 are associated with a significant minority of patients with BCR-ABL-negative chronic myeloid leukemias. The most common abnormality is the t(5;12)(q33;p13), which fuses the ETV6/TEL gene to the platelet-derived growth factor receptor-beta (PDGFRB), a receptor tyrosine kinase that maps to 5q33. PDGFRB is disrupted by other translocations and to date four additional partner genes (H4, HIP1, CEV14 and Rab5) have been reported. Clinically, most patients present with a myeloproliferative disorder (MPD) with eosinophilia, eosinophilic leukemia or chronic myelomonocytic leukemia and thus fall into the broader category of myeloproliferative disorders/myelodysplastic syndromes (MPD/MDS). With the advent of targeted signal transduction therapy, patients with rearrangement of PDGFRB might be better classified as a distinct subgroup of MPD/MDS.