The following symptoms are typical ones which lead parents and doctors to test for JMML, though children with JMML may exhibit any combination of them:

• Pallor
• Fever
• Infection
• Bleeding
• Cough
• Poor weight gain
• Macular-papular (discolored but not raised, or small and raised but not containing pus), often red, skin rash
• Lymphadenopathy (enlarged lymph nodes)
• Moderate hepatomegaly (enlarged liver)
• Marked splenomegaly (enlarged spleen)
• Leukocytosis (high white blood cell count in blood)
• Absolute monocytosis (high monocyte count in blood)
• Anemia (low red blood cell count in blood)
• Thrombocytopenia (low platelet count in blood)

Children with JMML and Neurofibromatosis 1 (NF1) (about 14% of children with JMML are also clinically diagnosed with NF1, though up to 30% carry the NF1 gene mutation) may also exhibit any of the following symptoms associated with NF1 (in general, only young children with NF1 are at an increased risk of developing JMML):

• 6 or more café-au-lait (flat, coffee-colored) spots on the skin
• 2 or more neurofibromas (pea-size bumps that are noncancerous tumors) on or under the skin
• Plexiform neurofibromas (larger areas on skin that appear swollen)
• Optic glioma (a tumor on the optic nerve that affects vision)
• Freckles under the arms or in the groin
• 2 or more Lisch nodules (tiny tan or brown-colored spots on the iris of the eye)
• Various bone deformations including bowing of the legs below the knee, scoliosis (curvature of the spine), or thinning of the shin bone

For more information on NF1, see:
The Children’s Tumor Foundation website
The March of Dimes quick reference to the Neurofibromatoses

Children with JMML and Noonan’s Syndrome may also exhibit any of the following most-common symptoms associated with Noonan’s Syndrome:

• Congenital heart defects, in particular, pulmonic stenosis (a narrowing of the valve from the heart to the lungs)
• Undescended testicles in males
• Excess skin and low hair line on back of neck
• Widely set eyes
• Diamond-shaped eyebrows
• Ears that are low-set, backward-rotated, thick outer rim
• Deeply-grooved philtrum (upper lip line)
• Learning delays

For more information on Noonan’s Syndrome, see:
The Noonan Syndrome Support Group, Inc.

If you need help with some of the medical terms included in these pages, please use the NIH Medical Glossary.