Herpes zoster of the nipple: rapid DNA-based diagnosis by the loop-mediated isothermal amplification method.

A 28-year-old Japanese man presented with grouped erosions and vesicles on an erythematous base affecting the right areola and the surrounding skin. A Tzanck smear from the vesicle revealed giant cells. An initial clinical diagnosis of mammary herpes simplex was considered but to explore the differential diagnosis, viral DNA was amplified by the loop-mediated isothermal amplification (LAMP) method. DNA replication was observed only in varicella zoster virus LAMP mixture, and this confirmed a diagnosis of herpes zoster. The patient was treated with 3000 mg of daily oral valacyclovir for seven days. After antiviral treatment, the lesion had healed and the pain had resolved completely.