Blastic plasmacytoid dendritic cell neoplasm arising from clonal hematopoiesis

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare subtype of myeloid neoplasm. Clonal evolution in the development of BPDCN remains to be elucidated. In the present study, we examined clonal evolution in a case of BPDCN by analyzing the distribution of gene mutations in tumor cells and non-tumor blood cells. The p.D1129fs and p.K1005fs TET2 mutations, p.P95H SRSF2 mutation, and p.L287fs NPM1 mutation were identified in a skin tumor at diagnosis and peripheral blood mononuclear cells at relapse. Notably, the p.D1129fs TET2 and p.L287fs NPM1 mutations were observed only in tumor cells, while the p.K1005fs TET2 and p.P95H SRSF2 mutations were found in both tumor cells and non-tumor blood cells. Recent genetic studies have suggested that some blood cancers may originate from clonal hematopoiesis, harboring somatic mutations. In the present case, the data suggest that BPDCN originated from clonal hematopoiesis with the p.K1005fs TET2 and p.P95H SRSF2 mutations via acquisition of the additional p.D1129fs TET2 and p.L287fs NPM1 mutations.