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.