Frequent varicella zoster reactivation associated with therapeutic use of arsenic trioxide: portents of an old scourge.

In 44 patients treated with arsenic trioxide (As2(O3)) for acute promyelocytic leukemia, 11 developed varicella zoster virus (VZV) reactivation (median 56 days [range 15-299]) after treatment. There was no preferential dermatome involvement or systemic spread. The actuarial risk of VZV reactivation at 1 year was 26%. No VZV reactivation occurred after the first year of initial treatment with As2(O3).