Добавил:
Upload Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз: Предмет: Файл:
Pediatric_Oncology_A_Comprehensive_Guide.pdf
Скачиваний:
23
Добавлен:
10.02.2016
Размер:
1.86 Mб
Скачать

44

T. Kühne

 

 

Myeloproliferative syndromes (MPS) are characterized by clonal proliferation patterns of hematological precursor cells with a tendency to develop acute leukemia. Cytopenias typically seen in myelodysplastic syndrome (MDS) are uncommon, as are dysplastic morphological features. Hence a pathogenesis different from MDS is suspected, which is an important reason to separate the discussion and classification of MPS from MDS

The new WHO classification of chronic myeloproliferative disorders also is for use in pediatric patients (please refer to Germing et al (2008), Vardiman (2010), Yin et al (2010))

WHO classification of chronic myeloproliferative disorders neoplasms

Chronic myelogenous leukemia (CML) – (Philadelphia chromosome, t(9;22)(q34;q11),

BCR/ABL-positive

Chronic neutrophilic leukemia (CNL)

Polycythemia vera

Primary myelofibrosis

Essential thrombocythemia

Chronic eosinophilic leukemia (CEL)

Myeloproliferative neoplasm, unclassifiable

5.1Juvenile Myelomonocytic Leukemia (JMML)

Belongs to myelodysplastic/myeloproliferative neoplasms

There are four diseases belonging to the category of myelodysplastic/myeloproliferative neoplasms: chronic myelomonocytic leukemia, atypical CML, BCR-ABL1 negative, juvenile myelomonocytic leukemia, and myelodysplastic/myeloproliferative neoplasm, unclassifiable

Was previously termed “juvenile chronic myelogenous leukemia” (JCML)

Morphological and cytogenetic relationship with CML is poor; however, there are similarities with chronic myelomonocytic leukemia (CMML)

Aggressive myeloproliferative disorder of the young child which can have some myelodysplastic features

The etiologic factors are all now shown to be specific genes that relate to RAS pathway signaling

5.1.1Clinical Manifestations

Paleness (69% of patients)

Fever (61% of patients)

Exanthema (39% of patients)

5 Myeloproliferative and Myelodysplastic/Myeloproliferative Neoplasms

45

 

 

Hepatosplenomegaly (more than 90% of patients)

Lymphadenopathy (75% of patients; Niemeyer et al. 1997)

5.1.2Laboratory Findings

Blood count: more than 10 × 109 leukocytes/l, more than 1 × 109 monocytes/l, low blast number except in accelerated phase

Bone marrow is hypercellular: less than 30% blasts except in accelerated phase

Cell cultures: spontaneous growth of granulocyte-macrophage precursors (colony- forming units – granulocyte-macrophage (CFU-GM)

Hemoglobin F (HbF) increased (disproportionate to age-related values) along with abnormal expression of small i antigen on RBCs

Clonalchromosomalaberrationsmostcommonincludemonosomy7anddel(7q). Philadelphia chromosome: t(9;22)-negative

5.1.3Natural History

Individual prognosis and time to disease progression are yet to be elucidated.

5.1.4Prognosis

Factors with prognostic significance:

Age: infants (less than 1 year old) have a higher chance of survival

Low platelet count (less than 100 × 109/l or less), increased HbF (more than

10–15%), more than 4% of blasts in peripheral blood, and more than 5% leuke- mic blasts in bone marrow appear to be associated with a poor prognosis

5.1.5Therapy

Therapy is controversial:

Scant data because of low patient numbers, i.e., there is no standard therapy. Neither mild nor intense chemotherapy, splenectomy, radiotherapy or cytokine treatment cure the disease or appear to improve outcomes

Allogeneic hematopoietic stem-cell transplantation is the only therapeutic option with the potential to increase survival

Although different agents with a potential effect have been studied (e.g., anti-RAS peptides as targets of specific immunotherapies, farnesylation inhibitors, inductors of apoptosis), no advantages of these treatments to the outcomes obtained with transplantation have been observed

Соседние файлы в предмете [НЕСОРТИРОВАННОЕ]