Many conditions can cause a leukocytosis. The presence of certain findings may be an early warning sign for an underlying acute or chronic hematologic malignancy.

Patient selection: unexplained leukocytosis


B symptoms (associated with malignant lymphoma)

(1) unexplained loss of more than 10% of body weight in the 6 months before diagnosis

(2) unexplained fever with temperatures above 38°C

(3) drenching night sweats

(4) pruritis that is recurrent, generalized and otherwise unexplained and which ebbs and flows parallel to disease activity


Other symptoms:

(1) easy bruisability or bleeding tendency

(2) unexplained fatigue or weakness

(3) immunosuppression


Findings on physical exam:

(1) petechiae or bruises

(2) lymphadenopathy

(3) hepatosplenomegaly

(4) pallor


Laboratory findings:

(1) unexplained anemia

(2) thrombocytopenia or thrombocytosis

(3) immature/unidentified/atypical cells or blasts on peripheral blood smear

(4) persistent lymphocytosis, especially in an older adult

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