Management of Mastocytosis and Mast Cell Activation in Children.

Mastocytosis is characterized by mast cell infiltration in various tissues and organs. More than half of the patients are children. Pediatric mastocytosis has several features that differentiate the disease from adult mastocytosis. Importantly, the disease, which usually starts in the first months of life or at birth, often shows a transient course with spontaneous resolution in adolescence. In most children, mastocytosis is limited to skin. Cutaneous involvement can present as maculopapular cutaneous mastocytosis, mostly with the polymorphic variant, cutaneous mastocytoma, or diffuse cutaneous mastocytosis. When children present with monomorphic maculopapular skin lesions, the variant typically seen in adults, this may indicate rare persistent disease until adulthood, often associated with systemic mastocytosis. Many pediatric patients suffer from symptoms of mast cell activation, ranging from pruritus to flushing and blistering. Children with cutaneous mastocytosis typically exhibit mutations in various regions of the KIT gene, whereas those with systemic disease predominantly carry KIT D816V. Diagnosis is mainly based on noninvasive measures, including skin inspection, elicitation of the Darier's sign, and analyses of the serum tryptase and KIT variant in blood. Treatment options encompass avoidance of triggers of mast cell activation, H1 and H2 antihistamines, cromolyn, and omalizumab. In children with systemic mastocytosis, tyrosine kinase inhibitors tailored to the specific KIT variant may be considered.