Azathioprine-induced anagen effluvium: report of an uncommon adverse effect

Abstract

Azathioprine is an immunosuppressant widely used in autoimmune dermatological conditions. It is a purine analogue and acts by inhibiting an enzyme involved in DNA synthesis, affecting cell proliferation. Adverse effects from this mechanism of action include bone marrow suppression, liver disorders, and, dermatologically, oral ulcers and a few reported cases of anagen effluvium. Some of these manifestations may be related to low levels of the enzyme thiopurine methyltransferase, which is responsible for inactivating purine metabolites. Anagen effluvium typically occurs in the first few weeks after starting azathioprine and is usually reversible upon discontinuation of the drug. We present the case of a 36-year-old female patient diagnosed with dry eye syndrome, treated with hydroxychloroquine and started on azathioprine 50mg/day, which resulted in agranulocytosis requiring hospitalization, and who subsequently developed diffuse hair loss 2 weeks after starting the immunosuppressant, without other associated predisposing factors, with a pattern suggestive of anagen effluvium, with a good clinical response after discontinuation of the immunosuppressant and treatment with topical and oral minoxidil, with rehairing one month after implementing the therapy, of particular interest due to the few reports published in the literature of anagen effluvium associated with the use of azathioprine and the rapid and excellent response to the discontinuation of azathioprine.