Nitroblue tetrazolium (NBT) test: criteria for false positivity and its use in practice.

The criteria for false positivity of the NBT test were described including absence of classical clinical signs of bacterial infection, negative blood (and, if necessary, other) cultures, and lack of response of antibacterial treatment as the basis for appreciation of positive NBT test result as false-positive. A case of acute lymphoblastic leukaemia with all the criteria being fulfilled was described.