congenital fibrosarcoma
A fibrosarcoma that occurs in infants. It shares identical morphologic features with adult fibrosarcoma but carries the t(12;15)(p13;q25) translocation that results in ETV6-NTRK3 gene fusion. It usually affects the superficial and deep soft tissues of the extremities. The prognosis is generally much more favorable than for adult fibrosarcoma, and it rarely metastasizes.