FDG Uptake Extending From the Dorsal Root Ganglion to the Sciatic Nerve After Herpes Zoster

A woman in her 50s receiving paclitaxel, carboplatin, and pembrolizumab for recurrent cervical cancer developed herpes zoster and received antiviral therapy. 18F-FDG PET/CT performed 22 days after zoster onset, when the skin lesions had crusted, demonstrated continuous uptake extending from the left L5 dorsal root ganglion to the sciatic nerve. To our knowledge, this is the first reported case of FDG PET findings indicating ganglioneuritis extending from the dorsal root ganglion to a peripheral nerve after herpes zoster. Recognition of this pattern is important in patients receiving chemoimmunotherapy because it may mimic immune-related neuritis or perineural tumor spread.