This case report documents the first karyotypic, fluorescence in situ hybridization, and genetic analysis of an angiomatoid fibrous histiocytoma that arose and recurred in the arm of a 5.5-year-old girl. Complex rearrangements between chromosomes 2, 12, 16, and 17 were noted, as well as deletion in the long arm of chromosome 11. Flow cytometry revealed a normal cell population. The t(12;16) site was further investigated using reverse transcriptase-polymerase chain reaction. We found that the FUS (also known as TLS) gene from 16p11 combined with the ATF-1 gene from 12q13 to generate a chimeric FUS/ATF-1. The FUS gene is rearranged in the t(12;16)(q13;p11) that characterizes myxoid liposarcoma and in acute myeloid leukemia with t(16;21)(p11;q22), while the ATF-1 gene is rearranged in the t(12;22)(q13;q12) found recurrently in clear cell sarcomas (malignant melanoma of soft parts). Thus, the FUS/ATF-1 gene in angiomatoid fibrous histiocytoma is predicted to code for a protein that is very similar to the chimeric EWS/ATF-1 found in clear cell sarcoma.