Treatment of infantile fibrosarcoma associated to an abdominal aortic aneurysm with larotrectinib: a case report.

Infantile fibrosarcoma (IFS) is a rare pediatric tumor which often presents the ETV6-NTRK3 gene fusion. NTRK3 encodes the neurotrophin-3 growth factor receptor tyrosine kinase, a druggable therapeutic target. Selective tropomyosin receptor kinase (TRK) inhibitors, such as larotrectinib, have shown efficacy and safety in the treatment of IFS. We report a case of an abdominal IFS diagnosed in a newborn associated with an aortic aneurysm that was successfully treated with larotrectinib without relevant adverse effects.