Leukemoid reaction in malignant bone tumor patients - a retrospective, single-institution study.

BACKGROUND To the Authors' knowledge, the literature regarding leukemoid reaction in patients with malignant bone tumor is sparse, and most of patients with leukemoid reaction have poor prognosis. AIM To study the leukemoid reaction in malignant bone tumor patients. MATERIALS AND METHODS A total of 105 consecutive malignant bone tumor patients with a white blood cell count > 50,000/microL were retrospectively identified over a 4-years period (2007-2010). Those patients without a secondary cause of their leukocytosis were defined as having a paraneoplastic leukemoid reaction. RESULTS Three etiologies of the leukocytosis were found in those 105 patients: the major one was paraneoplastic leukemoid reaction which accounted for 56%; the second one was hematopoietic growth factors defect accounting for 30%; 14% patients were caused by infection and Tumor bone marrow involvement. The patients diagnosed with a paraneoplastic leukemoid reaction typically had neutrophil predominance (94.8%) and radiographic evidence of metastatic diseases (78%). They were clinically stable, but had a poor prognosis. 95% either died or were discharged to hospice within 12 weeks of their initial extreme leukocyte count. Both of the 2 (2%) patients who survived over 12 weeks received effective antineoplastic therapy. CONCLUSIONS Patients with typical paraneoplastic leukemoid reaction were clinically stable despite having large tumor burdens. However, clinical outcomes were poor unless receiving an effective antineoplastic treatment.