Mosaic Li–Fraumeni syndrome in acute lymphoblastic leukemia

Li–Fraumeni syndrome (LFS) is a rare autosomal dominant tumor predisposition syndrome with high penetrance. The pathogenesis of the syndrome involves germline pathogenic variants in the TP53 gene. The spectrum of cancers in LFS predominantly includes solid tumors, with hematologic malignancies occurring in only 4% of cancer diagnoses. Most patients have a family history of the disease, however, in 10–20% of cases, germline variants are de novo . The introduction of next generation sequencing into clinical practice has made it possible to describe rare cases of mosaic LFS syndrome in some patients with solid tumors. This article presents the first described clinical case of mosaic LFS in a patient with hematologic malignancy. This case demonstrates how detailed molecular genetic testing using modern diagnostic techniques can determine the true origin of a pathogenic variant in the TP53 gene. The results of treatment show that, despite existing therapeutic options, patients with hematologic malignancies and LFS, including mosaic LFS, represent a challenging therapeutic group requiring the development of specialized treatment protocols.