The authors describe the case of a 3-year-old girl with acute lymphoblastic leukemia which was diagnosed several months after the appearance of the first symptoms. The delay can be attributed to the vague symptoms at onset in the form of a single laterocervical adenopathy which responded to antibiotic and antiphlogistic therapy, the total absence of any indicative hematological symptoms and the patient s persistent excellent general conditions. In the light of this unusual case, the authors stress the need to carry out invasive diagnostic tests on lymph node lesions that are often defined as aspecific given that they may occasionally disguise more severe lymphoproliferative diseases.