FDG PET characteristics of intraneural perineurioma: patient series.

backgroundIntraneural perineuriomas (INPs) are rare benign peripheral nerve sheath tumors with characteristic clinical and MRI features. Their 18F-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.