Herpes zoster infection mimicking pelvic lymph node metastasis on FDG-PET/CT in a patient with cervical cancer.

Although 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) is an established method for the staging of malignancies, benign lesions (e.g, active inflammatory lesions) often show increased metabolic activity. Herpes zoster is the clinical manifestation of the activation and replication of dormant varicella-zoster virus (VZV) in individuals with decreased cell-mediated immunity. Although the diagnosis of herpes zoster is clinical, it is sometimes observed incidentally during imaging for another disease. We describe the case of a 67-year-old Japanese female patient diagnosed with cervical cancer in whom FDG-PET/CT revealed herpes zoster manifestations: hypermetabolic cutaneous lesions in the buttock and pelvic lymph node involvement. The resected lymph nodes showed no malignant lesions but revealed lymphoid follicle formation, probably related to viral infection. There has been no report comparing FDG-PET findings of lymph nodes with histologic findings; the present findings are compatible with a clinically VZV-induced inflammatory reaction in regional lymph nodes, which increased FDG accumulation. Active infection with VZV displays increased FDG uptake in regional lymph nodes and may lead to incorrect malignant disease management in oncology. Misdiagnoses can be avoided by a careful interpretation by experienced nuclear medicine physicians as well as proper clinical evaluation.