E2484. Pathological Outcome of Unexpected or Incidental Focal FDG Activity in the Parotid Gland on PET/CT Scans: A Reason for Follow-Up
  1. Christopher Florido; University of Illinois at Chicago Hospital
  2. Raya Jadaan; University of Illinois at Chicago Hospital
  3. Nael Khayyat; University of Illinois at Chicago Hospital
The aim of this study was to evaluate the significance of focal intense activity within the parotid glands in patients who had PET scans for variable diseases.

Materials and Methods:
We retrospectively reviewed the PET/CT scans of the last 5 years at our institution. After excluding primary parotid tumors, 113 patients were found to have focal increased metabolic activity within the parotid gland. There were 11 breast, 18 lung, 4 colorectal, 19 head and neck, 9 melanoma, 12 lymphoma and 12 renal cell cancers. There were 28 additional pathologies (Sarcoidosis, Rosa Dorfman, Neurofibromatosis, Histiocytosis, multiple myeloma). Only patients with tissue sample diagnosis were included in the study.

Out of 113 patients, 9 had tissue diagnosis. Out of these 9, 6 had metastasis from the primary tumor, others included histiocytosis, Warthin’s tumor and pleomorphic adenoma. The head and neck cancers had more metastasis to the parotid gland (33% more). The parotid gland was the only site of metastasis for the renal cell cancer patient.

Focal increased FDG metabolic activity in the parotid gland requires further investigation especially in head and neck malignancy as the results may change treatment plan as there could be unexpected metastasis.