Abstract
Herpes zoster (HZ) is a viral infection caused by the reactivation of endogenous and latent varicella-zoster virus that remains dormant in the cranial nerve or dorsal root ganglia. HZ occurs in a portion of the general population, with a higher incidence observed in high-risk individuals. Patients with impaired immunity, including human immunodeficiency virus infection, organ transplantation, old age, and cancer-related treatments such as chemotherapy (CT) and radiotherapy (RT) were found more prone to HZ infection. We present a case of a 50-year-old patient who underwent a surgical excision of an invasive ductal carcinoma of the right breast. Following 15 fractions of RT, the patient presented with HZ appearing in the radiation field. The patient was treated successfully with Acyclovir, and RT was continued while on maintenance therapy with antiviral drugs. This case presents the importance of early diagnosis and the right choice of treatment in cancer patients and HZ due to the higher risk of complications and further development of the primary condition.