A mediastinal vasculogenic mesenchymal tumor and subsequent acute megakaryoblastic leukemia sharing a PTEN mutation: evidence of a common clonal origin —A Case Report

Background: Vasculogenic mesenchymal tumor (VMT) is a newly proposed vascular neoplasm that can develop in association with a mediastinal germ cell tumor (GCT), most commonly a yolk sac tumor, following chemotherapy. Levy et al defined VMT as an expansion of mesenchymal cells forming atypical vasculature, which did not meet the diagnostic criteria for angiosarcoma in several points, exceeding one low-power (4× objective) microscopic field. Additionally, Levy reported that the presence of VMT was associated with a high risk of developing hematological malignancies during the clinical course. Only a few reports have demonstrated genetic association between GCT and VMT, and genetic evidence linking VMT, and subsequent hematologic malignancies remains unclear.

Case description: We report herein a case of VMT associated with a mGCT that was retrospectively diagnosed, as VMT had not been established nosologically at the time of the initial diagnosis. Shortly after the VMT was excised, the patient experienced the development of acute megakaryoblastic leukemia (AMKL). The patient had a fatal outcome. Genetic analysis revealed that the VMT and leukemia shared a PTEN mutation, suggesting a common, clonal origin.

Conclusions: This case highlights VMT as an underrecognized entity which carries the risk of subsequent leukemia development and points to a genetic relationship between it and AMKL.