Azathioprine-induced severe pancytopenia: A serious complication in a patient with normal TPMT activity

Abstract

Azathioprine is an immunomodulator commonly used in renal transplant recipients and to treat lupus erythematous, and inflammatory bowel disease, and as second-line therapy in cases of rheumatoid arthritis. Here, we present a case of non-segmental vitiligo treated with low-dose azathioprine developing life-threatening pancytopenia with febrile neutropenia and trephine biopsy-proven drug-induced myelosuppression. The patient needed broad-spectrum antibiotics and granulocyte colony-stimulating factor (G-CSF) support with intermittent transfusion of blood products to completely recover from myelosuppression. It took almost a month for the patient to completely recover from the cytotoxicity caused by azathioprine. Interestingly, the patient had normal thiopurine methyl transferase (TPMT) activity and wild-type TPMT allele. We tried to outline how these types of patients can be managed and to emphasize the need for continuous monitoring of blood counts in patients receiving azathioprine to prevent life-threatening cytopenia even with normal TPMT activity and wild-type TPMT allele.