Criteria for the Regression of Pediatric Mastocytosis: A Long-Term Follow-Up

BACKGROUND: Mastocytosis is a neoplastic condition characterized by the accumulation of mast cells (MCs) in 1 or more organ. Adults tend to have persistent, systemic mastocytosis, whereas MC infiltration in children is usually limited to the skin and typically regresses after several years. Both adults and children could display mast cell activation symptoms (MCASs) due to MC mediator release. In more than 85% of both adult and pediatric cases, KIT mutations are present, with the KIT D816V mutation being present in most affected adults but in only half the affected children. OBJECTIVE: To identify the clinical, biological, and molecular factors associated with the regression of cutaneous mastocytosis (CM) in children, and to assess the correlation between MCASs and CM regression. METHODS: Patients having suffered from pediatric-onset mastocytosis for at least 8 years were included in a longitudinal cohort study. Clinical data, the baseline serum tryptase level, the KIT sequence, and the progression of MCASs and CM were recorded. RESULTS: CM regressed in 210 of the 272 included patients (77.2%; mean time to regression, 6.10 years). The rare cases of aggressive systemic mastocytosis were symptomatic from the outset. Congenital mastocytosis and the KIT D816V mutation were associated with CM regression (odds ratio, 0.48, P = .031, and 0.173, P = .031, respectively). Aggravation of MCASs over time was correlated with the persistence of skin lesions. However, the MCASs became more intense in 19% of the patients with MCASs at baseline and CM regression, justifying long-term follow-up in this setting. CONCLUSIONS: Our results open up new hypotheses with regard to the spontaneous regression of CM in pediatric patients. (C) 2020 American Academy of Allergy, Asthma & Immunology

Automated summary

The regression of cutaneous mastocytosis in pediatric patients is associated with congenital mastocytosis and the KIT D816V mutation. The worsening of MCASs over time is correlated with the persistence of skin lesions, but in 19% of patients with MCASs at baseline and CM regression, MCASs become more intense. Additional long-term follow-up in this setting is justified.