The 8p11 myeloproliferative syndrome (EMS), also called stem cell leukemia/lymphoma (SCLL), is a relatively rare condition characterized in its typical form by the occurrence, either simultaneously or sequentially, of a bcr/abl-negative myeloproliferative disorder and a lymphoma, usually a precursor T lymphoblastic lymphoma. The disease most often terminates in acute myeloid leukemia which is resistant to conventional chemotherapy. The defining cytogenetic abnormality, a translocation at the 8p11 locus, always involves the fibroblast growth factor 1 (FGFR1) gene. To date, eight partner genes have been identified in association with FGFR1 rearrangements. The most frequent FGFR1 translocation partner is the zinc finger gene ZNF198 located at 13q11. The t(8;13)(p11;q11) disrupts intron 8 of the FGFR1 gene and fuses proline-rich and zinc finger domains of the ZNF198 gene with the cytoplasmic tyrosine kinase domain of FGFR1. Oligomerization of the fusion protein occurs, with subsequent activation of downstream signal transduction pathways, culminating in neoplastic cell transformation. This review describes the historical development of the EMS/SCLL and outlines its cytogenetic abnormalities and molecular mechanisms with an illustrative case.