This study aims to describe immunophenotypic studies at diagnosis and follow up of a pediatric patient with leukemic phase of ALK+ anaplastic large cell lymphoma (ALCL) by multiparametric flow cytometry (MFC). An 8-color MFC combination of antibodies allowed to identify neoplastic cells in concentrations until 0.02% during minimal residual disease (MRD) monitoring. Immunophenotypic shifts occurred in key markers as CD30, CD7, CD2 and CD5, however neoplastic cells were clearly discriminated from normal populations. MFC can be a useful tool for ALCL diagnosis and MRD monitoring and may support therapeutic decisions.