Acquired Pelger-Huët anomaly in association with concomitant tacrolimus and fluconazole therapy following allogeneic bone marrow transplantation.

A 38-year-old Japanese woman with severe aplastic anemia received an allogeneic bone marrow transplant from her serologically HLA-identical father. Cyclosporine and methotrexate were administered to prevent graft-versus-host disease (GVHD). However, grade III acute GVHD developed on day 44, which was successfully treated with methylprednisolone and tacrolimus. Fluconazole therapy was started for oral candidiasis on day 112, but she complained of headache soon after. In addition to glycosuria and increased serum creatinine levels, Pelger-Huët anomaly of granulocytes was found in her blood, which disappeared after discontinuation of tacrolimus. Transient occurrence of Pelger-Huët cells may be associated with tacrolimus toxicity due to drug interaction with fluconazole.