Chronic neutrophilic leukemia (CNL) is a very rare myeloproliferative neoplasm (MPN) of elderly characterized by sustained neutophilic leucocytosis (>25000/cumm). Considering its rare entity, herein we report a case of CNL in an 80year old man who presented with dyspnoea, pleurisy and PUO. Persistent neutrophilic leukocytosis in a case of PUO in an elderly patient similar to this case can lead to a mistaken underdiagnosis. Suspicion is therefore required, to diagnose a case as CNL, if a patient presents with sustained neutrophilic leukocytosis without any underlying cause, not responding to higher antibiotics.
CNL, MPN, PUO, Sustained neutrophilic leukocytosis.