Clinical symptoms
JMML presents with fever and respiratory symptoms

Physical findings
These include facial rash, lymphadenopathy, splenomegaly and bleeding problems, pharyngotonsillitis, and bronchiolitis

Hematologic Features

• Blood counts: Leukocytosis (usually <50x109/L); monocytosis in the peripheral blood, which exceeds 5x109/L, thrombocytopenia; presence of nucleated red cell on blood smear, and circulating immature myeloid cells and a few blasts.
  
  
• Bone marrow reveals increased cellularity with increased myeloid series, monocytes comprise 5-10% of myeloid cells with some blasts.
  
  
• Sixty-eight percent of JMML cases lack cytogenetic abnormality: Monosomy 7 is seen in 6%.
  
  
• Erythropoiesis of fetal characteristics:
  
  
  • Increased fetal hemoglobin level (> 10%)
    
    
  • Decreased HbA2
    
    
  • Increased levels of G6PD, phosphoglycerate kinase, and enolase in red blood cells.
    
    
  • Decreased I antigen expression
    
    
• Immunologic abnormalities:
  
  
  • Increased immunoglobulin levels
    
    
  • Increased incidence of ANA positivity
    
    
• Vitamin B12 levels are elevated.
  
  
• Lysozyme levels are increased in 70% of patients.
  
  

Clinical Criteria for Diagnosis of Juvenile Myelomonocytic Leukemia:

• Hepatosplenomegaly
  
  
• Lymphadenopathy
  
  
• Pallor
  
  
• Skin rash
  
  
• Absence of t (9;22)
  
  
• Bone marrow blasts less than 20%
  
  
• Peripheral blood monocytosis greater than 1x109/l and at least two of the following:
  
  
  • Spontaneous in vitro growth of granulocyte macrophage progenitors (CFU-GM)
    
    
  • HbF elevated for age
    
    
  • Peripheral blood myeloid precursors
    
    
  • Leukocyte count greater than 10x109/L
    
    
  • Chromosome abnormalities
    
    

Prognosis
The prognosis is poor. The median survival is less than 9 months.

Treatment
High dose of an alkylating agent, total-body irradiation, and BMT is the only treatment with potential for cure and is the treatment of choice when a suitable donor is available.

Chemotherapy is of limited value.

Temporary improvement in clinical status may be achieved with the use of VP16 alone, standard AML therapy, or treatment with 13-cis-retinoic acid (100 mg/m2/day for infants less than 1 year of age). Expected complete response from 13-cis-retinoic acid is 25%.