Desmoid type fibromatosis in pediatric and young adults from French databases: Clinical characteristics and initial outcome according to age

•Clinical DTF presentation is more aggressive in children than young adults.•DTF were larger in children.•DTF were more frequently located in the abdomen and mesentery in young adults.•Active Surveillance seems to be a valid first-line option preventing overtreatment.•Progression is linked to size and location (extremities and trunk), regardless of age.