A 56 years old man has painful rashes over his right upper eyelid and forehead for the last 48 hours. He underwent chemotherapy for Non-Hodgkin's lymphoma one year ago. His temperature is 98° F, blood pressure 138/76 mm Hg and pulse is 80/ minute. Examination shows no other abnormalities. Which of the following is the most likely diagnosis -
Impetigo
Herpes zoster
Pyoderma gangrenosum
Erysipelas