Lymphoblastic lymphoma (LBL) is a neoplasm of lymphoid precursors presenting usually as acute leukemia with bone marrow and peripheral blood involvement. Primary cutaneous involvement of LBL with a pre-B phenotype has to be considered an extremely uncommon occurrence, accounting for less than 1% of all non-Hodgkin lymphomas. A child with an LBL involving a single cutaneous manifestation of 6 months duration is presented. At the time of presentation, the lesion consisted of a rapidly enlarging deeply infiltrated tumor on the upper arm. Immunophenotypic analysis performed an paraffin-embedded and frozen tissue sections revealed 2 pre-B phenotype of the tumor cells. Similar results were obtained from lymph node and bone marrow biopsy specimens. After 26 months of polychemotherapy, the patient is currently in complete remission. We wish to add this case to the current literature of LBL with cutaneous involvement, emphasizing the importance of a correct diagnosis and the excellent response to the therapeutic regimen.