A father brings his two-year-old daughter to your office for evaluation of a painful rash on her right upper extremity (pictured below)
What is the most likely diagnosis?
Herpes zoster results from reactivation of latent varicella-zoster virus 0fl.V), the virus that causes chickenpox.
Initial infection of a naive host by VZ.V causes chickenpox.
Upon resolution of this primary infection, immunity develops, and VZ.V retreats to the dorsal root ganglion of cutaneous sensory nerves where it remains in a latent state enjoying shelter from the immune system.
The factors that cause reactivation of latent VZ.V are unknown.
Classically, herpes zoster manifests clinically with a prodrome of neuropathic pain isolated unilaterally to one dermatome.
Subsequently, crops of grouped vesicles with underlying erythema erupt in that same dermatome accompanied by severe pain.