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Myelodysplasia

 

 

 

Juvenile Myelomonocytic Leukemia (JMML)

 

This is a chronic myeloproliferative disorder

Rare disorder - about 4/million annual incidence in North America

Affects young children (over 95% of cases diagnosed before age 4)

15% of cases associated with Neurofibromatosis type 1

 

Children usually present with:

  • Splenomegaly
  • Lymphadenopathy
  • Skin rash

 

Peripheral blood:

Immature myeloid precursors (myelocytes, promyelocytes, and myeloblasts) present in the peripheral blood:

  • Leucocytosis - elevated white blood cell count > 13 x 109/L (corrected for nucleated red blood cells)
  • Monocytosis (absolute monocyte count > 1 x 109/L - corrected)
  • Thrombocytosis (variable degree of left shift)
  • Circulating nucleated red blood cells
  • Usually have elevation of fetal hemoglobin (HbF)

 

Bone Marrow:

  • Hypercellular marrow with mildly increased M:E ratio (typically 5:1)
  • < 30% blasts

No Ph chromosome is ever present on cytogenetic assessment

 

Therapy:

  • Intensive chemotherapy alone and trans retinoic do not give a durable remission
  • Complete remissions have only been achieved with stem cell transplantation

 

Below is the image from Nature at : www.nature.com/.../v21/n5/fig_tab/2404596f1.html

Bone marrow aspirate in Juvenile Myelomonocytic Leukemia (JMML):

Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author

Morphology of JMML. Bone marrow smears were stained with May–Grünwald-Giemsa and shown at 1000-fold magnification. Bd=band, Bl=myelomonoblast, Eb=erythroblast, Mc=myelocyte, Mo=monocyte, Pm=promyelocyte, Se=segmented neutrophylic granulocyte.

 

External Links:

Juvenile Myelomonocytic Leukemia at the National Cancer Institute

The JMML Foundation

 

 

 

 

 

 

 

 

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