Chronic neutrophilic leukemia evolving from a myelodysplastic syndrome.

Chronic neutrophilic leukemia (CNL) is a rare hematologic disorder usually presenting with a persistent neutrophilia in the leukemoid range (WBC > 40-50 x 10(9)/1) and consisting largely of mature neutrophils. Patients have no obvious cause for an elevated white count and typically have an elevated leukocyte alkaline phosphatase score, hepatosplenomegaly, elevated vitamin B12 and are Philadelphia chromosome-negative. CNL has occasionally been associated with paraproteinemia or outright myeloma. Dysplastic features within the neutrophils in CNL have rarely been reported. We report the clinical, pathological and cytogenetic features of a case of CNL in an elderly white female initially diagnosed with refractory anemia with excess blasts, which subsequently progressed to CNL.