Radiation recall myositis in pediatric Ewing sarcoma.

Radiation recall is a rare and poorly understood phenomenon, characterized by an acute inflammatory reaction within the previously irradiated area, triggered by a precipitating systemic agent. This reaction typically affects the skin, and radiation recall myositis in the absence of cutaneous involvement has rarely been described in the literature. In this report, we present two cases of radiation recall in pediatric Ewing sarcoma patients receiving successive proton radiotherapy and chemotherapy, with magnetic resonance imaging (MRI) of muscle edema within the prior radiation fields.