Tacrolimus is an immunosuppressant that inhibits T-cell production by blocking the enzyme calcineurin. It is often prescribed after (kidney) transplants to prevent donor organ rejection. In addition to affecting lymphocytes, the drug can also cause dysplasia in neutrophilic granulocytes.

In this patient, who underwent kidney transplantation, neutrophilic granulocytes are seen with highly abnormal nuclear structure and chromatin.