Nucl Med Mol Imaging.  2007 Oct;41(5):359-363.

Incidental Benign Parotid Lesions on FDG-PET: Prevalence and Clinico-pathologic Findings

  • 1Department of Nuclear Medicine, Seoul National University College of Medicien, Seoul National University Bundang Hospital, Korea.
  • 2Department of Pathology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seoul, Korea.


PURPOSE: Incidental parotid lesions on F-18 FDG-PET can mimic distant metastasis of underlying malignancy. The prevalence and the clinico-pathologic findings of PET positive parotid lesions have not been known. We investigated how often incidental parotid lesions are found on clinical FDG-PET studies and what the clinico-pathologic characteristics of those parotid lesions are in the present study.
We retrospectively reviewed 3,344 cases of FDG-PET which had been obtained in our hospital from May 2003 to Dec 2006. The indications of FDG-PET were: evaluation of known/suspected cancer (n=3,212) or screening of cancer in healthy subjects (n=132). Incidental parotid lesion on FDG-PET was defined as an un-expected FDG uptake in one of parotid glands which was not primary target lesion of current FDG-PET. FDG uptake was represented by maximum standardized uptake value (maxSUV). Final diagnosis was made by pathologic analysis or clinical follow-up assessment.
Fifteen (0.45% = 15/3,344) incidental parotid lesions were found and they were all benign lesions. The maxSUV ranged from 1.7 to 8.6 (mean+/-s.d.=3.7+/-1.9). Final diagnoses of the incidental parotid lesions were; Warthin's tumor (n=2), pleomorphic adenoma (n=1), other un-specified benign lesion (n=1), and benign lesions under bases of imaging studies (n=3) and of clinical follow-up (n=8).
All of incidentally found parotid lesions in clinical FDG-PET studies were confirmed as benign lesions with prevalence of 0.45%. Close follow up using PET or CT might be a reasonable approach for determining the nature of incidentally found parotid lesions.


FDG-PET; parotid gland; incidentaloma

MeSH Terms

Adenoma, Pleomorphic
Follow-Up Studies
Mass Screening
Neoplasm Metastasis
Parotid Gland
Retrospective Studies
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