CSF3 and neutropenia: Although rare, anti-B-cell therapies can cause acute or late-onset neutropenia.<h4>Methods</h4>We report a case of severe recurrent fluctuating neutropenia after ofatumumab treatment.<h4>Results</h4>We observed four recurrences even after pausing with ofatumumab and repeated granulocyte stimulating factor (G-CSF) treatment.