18F-FDG PET/CT manifestations of extra-adrenal retroperitoneal ganglioneuroma: a retrospective study of 21 cases.

OBJECTIVE

Current literature on the fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) features of retroperitoneal ganglioneuroma (GN) remains limited, consisting primarily of isolated case reports. This study therefore aimed to investigate its 18F-FDG PET/CT characteristics to improve recognition among nuclear medicine physicians. MATERIALS AND

METHODS

In this retrospective single-center study, 21 patients with pathologically confirmed extra-adrenal retroperitoneal GN who underwent 18F-FDG PET/CT imaging between December 2009 and June 2025 were enrolled. The clinical information, FDG imaging features, and pathological data of the patients were collected and analyzed.

RESULTS

The study cohort comprised 11 males and 10 females, with a mean age of 37.7 ± 15.4 years. On CT imaging, the lesions typically appeared isodense or hypodense relative to muscle. They were generally large, with a mean size of 9.6 ± 4.8 cm. The morphological presentation was irregular in 14 (66.7%) cases and regular in seven (33.3%) cases. The associated features included calcification (n = 10), fat component (n = 6), and cystic change (n = 1). Of the cases with calcification, four also had a concurrent fat component. None of the cases showed necrosis or hemorrhage. The median maximum standardized uptake value (SUVmax) for the cohort was 2.9 (IQR: 2.2–3.7), with a range from 1.6 to 8.3. Following FDR correction, only calcification showed a significant association with lesion size (p = 0.016, r = 0.800). Other associations with lesion size were also nonsignificant. The corresponding correlation coefficients were r = 0.533 for fat, r = 0.469 for vascular encasement, and r = 0.173 for morphology. Comprehensive analysis, including both univariate and multivariate methods, revealed that no clinicoradiologic and pathologic features served as a robust and independent predictor of SUVmax in this cohort (all p > 0.05).

CONCLUSION

On 18F-FDG PET/CT, GN typically presents as a large, solitary mass with mild-to-moderate FDG avidity. This modality may provide descriptive and supportive information for GN. Calcification is a characteristic feature of GN and is markedly associated with increased lesion size. No clinicoradiologic and pathologic features showed a significant association with SUVmax. These findings require confirmation in future large-scale prospective studies.