Aplastic anemia secondary to azathioprine in systemic lupus erythematosus: report of a case with normal thiopurine S-methyltransferase enzyme activity and review of the literature.

Azathioprine-induced aplastic anemia and fatal myelosuppression is a rare occurrence in patients with systemic lupus erythematosus (SLE). We report a case of a 53-year-old female with a normal thiopurine S-methyltransferase (TPMT) level who developed aplastic anemia within 4 weeks of azathioprine initiation, resulting in death. Physicians should be vigilant in monitoring routine blood work when administering azathioprine, a relatively common drug, in patients with SLE.