The activation antigen CD30 (Ki-1) which is expressed by the lymphocytes T and B is related to the "nerve growth factor" (NFGR) like the receptor of the "tumor necrosis factor" (TNF) and is expressed in the group of large-cell anaplastic lymphoma (ACLC) and Hodgkin's lymphoma and in non-Hodgkin's lymphoma and within the T cells of infectious Mononucleosis. We describe a case of a 18 year-old who contracted Acute Infectious Mononucleosis showing lateral cervical lympho adenopathy. The histologic examination was suggestive for a large-cell anaplastic lymphoma with the antigen CD30, expressed by severa atypical immunoblasts. The remarkable immunoblastic proliferation with Reed-Sternberg-like cells, in milieu polymorphous inflammatory cells present in the course of Infectious Mononucleosis, can simulate large cell anaplastic lymphoma, as well as Hodgkins disease and non-Hodgkins lymphoma. The diagnosis for Infectious Mononucleosis is usually clinical and serological but in cases of cervical lymphnode biopsy a differential diagnosis must be done with positive lymphoma CD30. The criteria to differentiate histologically the Infectious Mononucleosis with large cell anaplastic lymphoma and non-Hodgkin s lymphoma are discussed. Finally, the relationship between Infectious Mononucleosis and lymphoproliferative disease Epstein-Barr virus related is examined.