A 42-year-old woman who had dermatomyositis developed reticulum cell sarcoma of the vulva after five months of azathioprine therapy. Experimental and clinical studies have demonstrated an increased incidence of reticulosarcoma with azathioprine treatment. It is postulated that the reticulum cell sarcoma was caused by the azathioprine and that immunosuppressive treatment in nonfatal disorders may involve an increased risk of developing a malignant tumor.
Wishart J. Reticulosarcoma of Vulva Complicating Azathioprine-Treated Dermatomyositis. Arch Dermatol. 1973;108(4):563-564. doi:10.1001/archderm.1973.01620250047015