Oral sirolimus for the treatment of juvenile xanthogranuloma: Report of two pediatric cases.

Juvenile xanthogranuloma (JXG) with extensive cutaneous or visceral organ involvement is often associated with high morbidity and treatment commonly involves surgical excision, radiotherapy, systemic steroids, or chemotherapy. Sirolimus, a mammalian target of rapamycin (mTOR) inhibitor, is an oral antitumor and immunosuppressive therapy used to treat various neoplastic disorders, including histiocytic disorders. We report two pediatric cases of JXG successfully treated with oral sirolimus monotherapy, and postulate that sirolimus may induce rapid disease resolution and long-term remission for patients with both skin-limited and multisystemic JXG. Our findings warrant further investigation of the relationship between the mTOR pathway and JXG.