If it appears unilaterally on the lower back, with clusters of papules and blisters, and the rash does not usually extend beyond the midline of the body, herpes zoster is more likely to be considered. Herpes zoster causes inflammation of the skin and the virus is latent in the body after the patient has had chickenpox, usually in the spinal ganglia or intracranial sensory ganglia, and can cause herpes zoster when the body’s immune system is weakened and the virus is reactivated.