[A case of chronic neutrophilic leukemia with abnormal karyotype]

A 75-year-old man was admitted to our hospital because of leukocytosis and thrombocytosis. The peripheral blood showed RBC 403 x 10(4)/microliters, Hb 14.1 g/dl, PLT 91 x 10(4)/microliters, and WBC 48,000/microliters with a differential count of 24% band forms, 65% segmented forms and 11% others. The bone marrow aspiration revealed myeloid hyperplasia (94.4% myeloid series, 4.8% erythroid series and 0.8% others), and NAP score was consistently high. The serum level of lysozyme and vitamin B12 were elevated. There were no signs of infection or other malignancy. Cytogenetic study of bone marrow cells showed mosaic karyotypes of 46,XY/46,XY,t(7;16) (q22;q24). The Ph1 chromosome was not found. A diagnosis of chronic neutrophilic leukemia was made. Serial chromosomal analysis showed the coexistence of a clone with 46,XY,t(7;16) (q22;q24) and that with 46, XY.