| Summary points: | A 23-year-old male is admitted to hospital because of leukocytosis discovered on routine medical examination. The case report describes the physical examination; laboratory findings; whole body CT; blood, urine, and sputum cultures; bone marrow aspiration; chromosome analysis; treatment; and outcome. The authors review the criteria necessary for the diagnosis of chronic neutrophilic leukaemia, prognosis, and treatment options. |