An otherwise healthy 36-year-old Caucasian man presented to the emergency department with a two-day history of fever, nausea, and headache. He was taking ibuprofen for four weeks because of lower back pain. On physical examination, there was nuchal rigidity and fever. Laboratory testing revealed an elevated C-reactive protein of 162 mg/ml, haemoglobin of 9.1 mmol/l, thrombocytes of 258 x 109/l, lymphocytes of 0.7x 109/l and 0.0 x 109/l neutrophilic, eosinophilic, and basophilic granulocytes in the peripheral blood. There was no previous granulocytes count known to be conducted. A lumbar puncture was performed and the spinal fluid revealed low glucose and 1 leucocyte/mm3 . Subsequently, a presumptive diagnosis of meningitis was made and treatment with meropenem initiated. The next day, a bone marrow biopsy was done (figures 1 and 2).