Hyperleukocytosis, an unusual paraneoplastic manifestation of lung cancer: Case report and review of literature.

Leukocytosis may be found in patients with lung cancer either at time of diagnosis or during the course of the disease. Though mild leukocytosis is common in lung cancer, hyperleukocytosis defined as total leukocyte count more than 100,000 is uncommon. We describe a 68-year-old chronic smoker who presented with osteolytic pelvic bone lesion and hyperleukocytosis, who on evaluation was found to have a primary lung cancer. Bone marrow aspiration and biopsy showed marked myeloid hyperplasia. Myeloid series comprised predominantly mature neutrophils and stab forms. Cytogenetic investigation showed a normal chromosome set (46, XY). Repeated cultures from blood, urine, and sputum were sterile. He was started on chemotherapy but had a progressive downhill course. In patient with lung cancer, leukocytosis can be due to infection, use of corticosteroid or hematopoetic growth factors, bone marrow involvement, or paraneoplastic manifestation. Paraneoplastic leukocytosis is associated with poor prognosis and aggressive disease.