KIT and systemic mastocytosis: Moreover, performing an abdominal ultrasound is also indicated, as organomegaly is a strong predictor of SM in children.Children with significant abnormalities in the complete blood count, organomegaly and a significantly elevated and/or rising serum tryptase level or other signs and symptoms suggesting the presence of advanced SM, or another systemic hematologic neoplasm, first require the determination of the KIT D816V mutation in PB using the sensitive allele-specific quantitative polymerase chain reaction (ASqPCR) [7,29,30,79].