1, 4 Extreme leukocytosis represents a diagnostic dilemma because of the need to rule out such secondary causes as infections, newly developed hematologic malignancies, use of corticosteroids or hematopoietic growth factors, severe hemorrhage, and metastases to bone with necrosis. 1 To our knowledge, its frequency in patients with nonhematologic cancer remains unclear, having been reported to range from 1% to 4% in small case series. 1- 3 Nonclonally derived mature neutrophils usually drive the leukocytosis.

© 2009 American Cancer Society.Įxtreme leukocytosis in solid tumor patients, variably defined as a white blood cell (WBC) count ≥40,000/μL or 50,000/μL, has been reported in nearly all solid tumor types and is historically associated with poor outcomes.

However, clinical outcomes were poor unless effective antineoplastic treatment was received. Patients with paraneoplastic leukemoid reactions typically were clinically stable despite having large tumor burdens. Infection was an uncommon cause of extreme leukocytosis in patients with solid tumors. All of the 8 (10%) patients who survived>1 year received effective antineoplastic therapy.

The patients diagnosed with a paraneoplastic leukemoid reaction typically had neutrophil predominance (96%) and radiographic evidence of metastatic disease (78%), were clinically stable, and had a poor prognosis 78% either died or were discharged to hospice within 12 weeks of their initial extreme leukocyte count. The etiology of the leukocytosis was hematopoietic growth factors in 522 (69%) patients, infection in 112 (15%) patients, high-dose corticosteroids in 38 (5%) patients, newly diagnosed leukemia in 9 (1%) patients, and paraneoplastic leukemoid reaction in 77 (10%) patients. RESULTS:Ī total of 758 (20%) patients with solid tumors and extreme leukocytosis were identified. Those patients without a secondary cause of their leukocytosis were defined as having a paraneoplastic leukemoid reaction. METHODS:Ī total of 3770 consecutive solid tumor patients with a white blood cell count>40,000/μL were retrospectively identified over a 3-year period (2005-2008). To the authors' knowledge, the literature regarding extreme leukocytosis in solid tumor patients is sparse, consisting of a few case reports and small case series.

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