Thought the disease is seen far more often in adults, children can also have systemic mastocytosis (SM), explains a recent review published in The Journal of Allergy and Clinical Immunology: In Practice.
SM in children is rare; most children with mastocytosis have the form that affects only the skin, called cutaneous mastocytosis (CM). The review’s authors noted that it’s not known how many children have SM, the form of mastocytosis that affects both the skin and organs inside the body.
Most children with SM have specific skin symptoms: small, uniform reddish-brown spots or bumps on their back, belly or limbs. Therefore, diagnosis usually begins with a careful skin exam.
A blood test for a protein called tryptase can help: levels above 20 ng/mL may suggest SM. Like adults, many children with SM carry a specific genetic mutation called KIT D816V, so doctors may also measure how much of this mutation appears in the blood. Rising tryptase levels or increasing amounts of KIT D816V — especially when skin spots worsen — should raise concern for SM.
An abdominal ultrasound is often helpful, because enlarged organs can be a sign of SM.
Read more about SM testing and diagnosis
Among children diagnosed with SM, the most common type is indolent SM, which usually progresses slowly. Very rarely, children may develop more serious forms, including aggressive SM, mast cell leukemia or SM that occurs together with other blood cancers like acute myeloid leukemia.
Bone-related issues such as osteopenia or osteoporosis, which are frequently seen in adults with SM, “are uncommon in pediatric patients, but may also be underdiagnosed,” the researchers said.
To treat children with SM, doctors use medicines called tyrosine kinase inhibitors that are tailored to the child’s specific KIT gene variant.
Children with widespread skin disease, very high tryptase levels, severe symptoms, or a history of anaphylaxis are usually prescribed an epinephrine autoinjector for safety.
Most children with mastocytosis — even those with SM — have a good long-term outlook, the researchers said.
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