This 58-year-old patient, recently diagnosed with secondary syphilis, presents with this painful skin eruption. The patient completed syphilis treatment, and his RPR titer decreased by four-fold, indicating successful treatment. No new medications, and HIV was negative. A review of system was otherwise unremarkable, denied recent upper respiratory illness, constitutional symptoms or sick contacts. Based on the clinical images, which of the following diagnostic tests is the most sensitive?

A. Tzanck smear (TS)

B. Viral culture

C. Polymerase chain reaction (PCR)

D. Direct fluorescent antibody (DFA)

E. Varicella zoster IgG

To find out the correct answer and read the explanation, click here. 

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