Abstract
2716
Introduction: 1. To evaluate spectrum of characteristic imaging findings and patterns of FDG uptake of parotid lesions on 18F-FDG PET/CT.
2. To correlate 18F-FDG PET/CT findings with other imaging modalities.
Methods: 18F-FDG PET/CT is routinely performed to detect, stage and evaluate treatment response for many solid cancers. Many nonmalignant pathologies of parotid gland may demonstrate FDG avidity, many of which may be confused with metastatic disease by those unfamiliar with these entities. No absolute SUV cut off can reliably differentiate benign from malignant lesions. Additional ultrasound, contrast CT and/or MRI correlation is helpful in better characterization of these lesions.
Results: We present a case based pictorial review highlighting the spectrum of benign and malignant FDG avid parotid lesions. With varying degree of FDG avidity. The spectrum of cases includes metastatic parotid lesions (from melanoma, colonic adenocarcinoma, lung adenocarcinoma, foot sarcoma), Warthin tumor, B cell lymphoma, follicular lymphoma, adenocarcinoma, salivary duct carcinoma, basal cell carcinoma, extra medullary multiple myeloma, acute myeloid leukemia, sialoliths, sialo adenitis, parotid abscess, parotitis in HIV, and epidermal inclusion cyst. Occasionally non-pathological uptake such as diffuse parotid uptake in patients on chemotherapy, non-specific prominent physiologic uptake or asymmetric uptake secondary to atrophy or surgical absence of contralateral parotid may appear abnormal.
Conclusions: 18F-FDG PET/CT is prone to many pitfalls and incidental findings in parotid gland because of nonspecific mechanism of FDG. The presented PET/CT based pictorial review with multimodality correlation raises awareness and strengthens the judgment of the reading physician.