Chronic Neutrophilic Leukemia (CNL) is an extremely rare myeloproliferative disorder that presents diagnostic challenges for both pathologists and treating clinicians.
Because it is very rare, and because it is typically a diagnosis of exclusion, it is important for pathologists and hematologists to be familiar with CNL when approaching the patient with a myeloproliferative clinical picture.
The cause of CNL is unknown.
Chronic neutrophilic leukemia features persistent neutrophilia, increased white blood cell production in the bone marrow, and enlargement of the liver and spleen (hepatosplenomegaly). Pruritus, gout, and mucocutaneous bleeding are occasionally seen.
Chronic Neutrophilic Leukemia is a rare and difficult diagnosis of exclusion.
Until the first decade of this century, the treatment of CNL focused on disease control rather than cure. Once the disease progressed to a more aggressive leukemia, there was typically little chance of obtaining a long-lasting remission because of the older age of most patients as well as the acquisition of multiple cytogenetic abnormalities with a poor long-term outlook.