RT Journal Article
SR Electronic
T1 Azathioprine-induced pancytopenia with normal TPMT activity presenting with HSV oral ulcers
JF BMJ Case Reports
FD BMJ Publishing Group Ltd
SP bcr-2018-225209
DO 10.1136/bcr-2018-225209
VO 2018
A1 Caroline H Jensen
A1 John Tiu
A1 Jillian S Catalanotti
YR 2018
UL http://casereports.bmj.com/content/2018/bcr-2018-225209.abstract
AB A 65-year-old man with treatment-resistant psoriatic arthritis, hypertension, dyslipidaemia and benign prostatic hyperplasia (BPH) presented with herpes simplex virus (HSV) oral ulcers and a recent 15 lb weight loss due to reduced consumption. Five weeks previously, his methotrexate was tapered and he had begun taking azathioprine. The patient’s thiopurine S-methyltransferase (TPMT) activity level was normal prior to starting azathioprine. He was found to have pancytopenia with normal folate levels and azathioprine was discontinued. His pancytopenia worsened, with a nadir 8 days after stopping azathioprine, before returning to normal levels. His oral ulcers improved and he was able to tolerate solid food. This case illustrates that decreased TPMT activity is not the only risk factor for pancytopenia as an adverse reaction to azathioprine. Furthermore, HSV stomatitis may be the presenting symptom of pancytopenia. The timeline of improvement in cell counts illustrated in this patient has implications for the management of suspected azathioprine-induced pancytopenia.