Incidental [18F]FDG-avid focuses in parotid glands on PET/CT

Abstract

Background The number of unexpected focal [18F]FDG-avid findings (incidentalomas) within the parotid gland (PGI) continues to increase with the expanding use of PET/CT scanning. The prevalence of malignancy in PGIs is uncertain and appropriate management is unsettled. Aims We aimed to explore the underlying pathologies associated with PGI. Materials and methods A retrospective review of all patients with parotid gland incidentaloma(s) treated at the Ear-Nose-Throat Department, Aarhus University Hospital, Denmark in the period 2012–2021, was performed. Results In total, 94 patients with one (n = 86) or two (n = 8) PGI(s) were included. In patients with one PGI, 72 (84%) focuses were benign, two (2%) focuses were malignant (both malignant melanoma metastases), and 12 (14%) focuses were undiagnosed. In patients with two PGIs, all 12 lesions with pathological examinations were benign (4 PGIs were undiagnosed). The median SUVmax found in benign lesions was higher (12.0) compared to malignant lesions (5.5) (p = .043). Conclusions and significance The prevalence of malignancy was low (2/94, 2.4%) in PGIs. Based on our findings, PGI in patients without a history of parotid malignancy, who undergo PET/CT scanning for reasons other than head and neck cancer (including malignant melanoma), may be managed similarly to patients with asymptomatic parotid gland tumors.