Paediatric mastocytosis: a systematic review of 1747 cases.

Paediatric mastocytosis was previously considered to be a benign and spontaneously regressing disease. However, this evolution is impossible to predict. To clarify the characteristics and course of paediatric mastocytosis, we performed a literature review of 1747 cases published between 1950 and April 2014. Lesions occurred before the age of 2 years in 90% of cases, and presented as urticaria pigmentosa (75% of cases), mastocytoma (20%) or diffuse cutaneous mastocytosis (5%). The male-to-female ratio was 1·4. KIT D816V mutation was detected in 34% of 215 tested patients. Clinical regression (complete or partial) occurred in 67% of cases and stabilization in 27%. However, the outcome was fatal in 2·9% of patients.