[Eosinophilic leukemia: a rare form of Philadelphia chromosome negative chronic myeloid leukemia?]

Eosinophil leukaemia is a rare and poorly defined entity characterized by neoplastic proliferation of eosinophil cell line. This form of the hypereosinophilic state is considered to be a variant form of CML, although as a diseases entity is not generally accepted. A history of a patients is reported, whose clinical course is thought to fulfill the requirements of eosinophil leukaemia. On the basis of the initial results (pathological lymphogram, eosinophilia, Ph-negativity) lymphogranulomatosis was suspected and explorative laparotomy was performed. However, only marked eosinophilic infiltration of the spleen was detected. After splenectomy his disease was stable without treatment for six months when his leukocytosis and eosinophilia increased. Despite the administration of hydroxyurea the leukocyte count exceeded 100 x 10(9)/l (eosinophil cells 70%), and the bone marrow revealed massive (80%) eosinophilic infiltration. Neither Ph-chromosome, nor cabl and bcr gen rearrangement were demonstrated, but the expression and amplification of c-myc oncogene indicated disease progression. Interferon therapy produced long-term clinical and haematological improvement, but blastic transformation was developed in the second year of his disease. Autopsy showed multiple organ involvement characteristic of CML, but no marked eosinophilic infiltration was found. The feature of this case suggest that eosinophil leukaemia might represent an uncommon form of Ph-negative CML.