Leukostasis in Chronic Lymphocytic Leukemia.

BACKGROUND Chronic lymphocytic leukemia (CLL) is a mature B cell lymphocytic neoplasm that has an indolent clinical course. Therefore, not all patients with CLL require treatment at the time of diagnosis. Hyperleukocytosis (white blood cell count, >100×10⁹/L) is present in a large proportion of patients with CLL. However, symptomatic hyperleukocytosis (leukostasis) is an extremely uncommon presentation of CLL. Leukostasis frequently presents with the clinical manifestation of respiratory, neurological, or renal system problems. This is secondary to the decreased tissue perfusion due to the intravascular accumulation of large aggregates of leukemic cells. Leukostasis is a medical emergency requiring intensive care unit (ICU) admission and its management includes aggressive hydration, prevention and treatment of tumor lysis syndrome, cytoreduction, and leukapheresis. CASE REPORT We report a case of a 77-year-old woman with a long history of untreated CLL who presented with respiratory symptoms with hyperleukocytosis. Her condition rapidly deteriorated, requiring intubation. She required induction chemotherapy with chlorambucil as well as 2 sessions of leukapheresis, to which she responded well. In most reported leukostasis cases in the literature, the white blood cell (WBC) count was >1000×10⁹/L. We present a case of a patient with leukostasis with WBC count 524×10⁹/L who responded to chlorambucil and leukapheresis, with good recovery. CONCLUSIONS Leukostasis, although extremely rare, is a life-threatening complication in patients with CLL. It should be strongly considered in the differential diagnosis of patients with CLL who present with hyperleukocytosis and acute pulmonary symptoms. Clinicians should be aware of this medical emergency, as delayed treatment can increase morbidity and mortality.