[Pseudohemopathy caused by rhabdomyosarcoma]

A 26-year-old male with a primary rhabdomyosarcoma of maxillary sinus is reported. The tumor was initially mistaken for an anaplastic Ki-1 positive anaplastic lymphoma in the histological preparation, owing to its high indifferentiation degree. After a smear study it was categorized as IEA, and chemotherapy of CHOP type was started; after two courses, local telecobalt therapy was given. After this was completed, the disease showed a progression, involving the bone marrow and resulting in clinical and cytological features consistent with acute leukemia. At that time we saw the patient for the first time. He is presently in complete remission after having started polychemotherapy of CVADIC type. After a commentary on the major study steps that led to the diagnosis, the crucial role of electron microscopy and, particularly, immunocytology for the correct identification of anaplastic tumors is emphasized.