Chronic myelocytic leukemia with features simulating myelofibrosis with myeloid metaplasia.

Abstract

Six patients with the typical clinical and hematologic features of chronic myelocytic leukemia plus characteristics of myelofibrosis with myeloid metaplasia are presented. These findings included (1) striking extramedullary hematopoiesis, exemplified by numerous red cell precursors and megakaryocytes, in the splenic aspirate in 4 patients, and in a subcutaneous mass and the left testis, respectively, in 2 patients; (2) marked fibrosis of the bone marrow on biopsy in 4 patients, first noted in 2 at the time of diagnosis of leukemia. Cytogenetic studies revealed the presence of the Philadelphia (Ph1) chromosome in 5 patients. Leukocyte alkaline phosphatase activity was initially absent and remained so in 5; in 2, activity rose from below normal and normal levels, respectively, to elevated levels during therapy. Demecolcin, a satisfactory therapeutic agent in typical CML, was more toxic for these 6 patients and was ineffective in reducing spleen size; busulfan was superior. The relation between CML and other myeloproliferative disorders is discussed and the authors concluded that in “overlap” cases neither karyotypic analysis nor estimates of LAP activity provides absolute diagnostic criteria.