This is seen in immunosuppressed patients usually on steroids, azathioprine, or cytotoxic agents following transplantation or for leukaemia or lymphoma.

• 在免疫受到抑制的病人可发生此病，患者因移植、白血病或淋巴瘤而常应用激素、硫唑嘌呤或细胞毒类药物治疗者。