Genioglossus Muscle Uptake on 18F-FDG PET/CT, Secondary to Hypoglossal Nerve Stimulation

A 59-year-old man with diffuse large B-cell lymphoma (DLBCL) underwent end-of-treatment 18F-FDG PET/CT demonstrating asymmetric linear uptake along the right tongue extending to the anterior hyoid bone without a CT correlate. His history included obstructive sleep apnea (OSA) refractory to CPAP, treated with a right hypoglossal nerve stimulator (HNS). The 18F-FDG PET/CT uptake was attributed to genioglossus muscle activation from neurostimulation. Increased 18F-FDG activity in head and neck muscles is known to occur with mastication, tongue biting, denervation, inflammation, and benign or malignant lesions. Genioglossus uptake related to HNS represents an important potential pitfall in oncologic PET/CT interpretation.