Varicella-Zoster virus encephalitis during standard induction chemotherapy for acute myeloid leukemia

We present two cases of acute myeloid leukemia (AML) who developed Varicella-Zoster Virus (VZV) encephalitis after completion of standard “3 + 7” induction remission chemotherapy. A 50-year-old patient developed disseminated cutaneous Herpes Zoster (HZ) 2 days after completion of induction chemotherapy for AML. The patient was treated with intravenous acyclovir 7 days and then orally. On the second day following intravenous acyclovir discontinuation confusion, cerebelar ataxia somnolescence and VZV encephalitis was diagnosed. The other 38-year-old patient developed neuroleukemia and VZV encephalitis without skin rash after completion of induction chemotherapy. In both patients the diagnosis was confirmed by polymerase chain reaction (PCR) for VZV DNA in serum and liquor. The first patient completely recovered after reinstitution of intravenous acyclovir while the other patient a month later. This is unusual presentation of VZV encephalitis occurring in a patient with AML after standard induction remission chemotherapy which implies the significance of early diagnosis and screening for viral infections in AML patients with unusual neurologic presentation even in absence of rash. The screening for viral infections should be performed because antiviral prophylaxis is not routinely recommended for AML during standard induction chemotherapy by most clinical guidelines.