Blastic plasmacytoid dendritic cell neoplasm is an aggressive and rare hematologic malignancy, exceptionally presented in children. This case reports an 11-year-old Peruvian boy, with a 2-year history of a purple-violate tumor in a leg, lymph node involvement, and histopathological study with immunohistochemistry: CD4+, CD56+, Tdt+, CD45+, TCL1+. An institutional treatment protocol for high-risk ALL was given. There was a diagnosis delay in a pediatric patient with a rare but very visible neoplasm in a low-middle income country. Despite this, the clinical course was of an indolent evolution. The institutional protocol was efficient to achieve complete oncological disease response.