Amrami, Abigail B.

BACKGROUND Intraneural perineuriomas (INPs) are rare benign peripheral nerve sheath tumors with characteristic clinical and MRI features. Their 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) appearance has not been characterized in a patient series. The authors evaluated FDG uptake patterns in INP. OBSERVATIONS The authors retrospectively reviewed that data of patients with confirmed INP who had MRI and FDG PET studies that included the affected nerve. Eight patients were included (5 male and 3 female; mean age 30.8 years, range 16–61 years). All lesions showed mildly increased FDG uptake relative to the contralateral nerve (lesion maximum standardized uptake value [SUVmax]: mean 1.5, median 1.2, range 1.1–3.5; contralateral nerve SUVmax: mean 0.9, median 0.9, range 0.8–1.0) and skeletal muscle background (SUVmean: mean 0.8, range 0.5–0.9). Six patients had denervation edema and/or fatty atrophy, without appreciably increased FDG uptake in the affected musculature. No additional abnormal hypermetabolic foci were identified. LESSONS INPs generally demonstrate low-level FDG uptake. PET is best regarded as a complementary test when already available or when metabolic characterization may refine the differential diagnosis; unexpectedly high uptake should prompt reconsideration of the diagnosis or additional evaluation. https://thejns.org/doi/10.3171/CASE26698