Pitfalls of Fluorine-18 Fluorodeoxy-D-Glucose Positron Emission Tomography in a Patient with Advanced Oral Cavity Cancer Treated by Radical Surgery with Adjuvant Radiotherapy: A Case Report

Abstract

Patients with advanced oral cavity cancer are primarily treated by surgery with adjuvant therapy. Such treatment often causes significant distortions of normal tissue and local inflammation, impairing accurate differentiation of recurrent tumor from normal post-treatment changes in conventional imaging modalities. Recently, 18F-2-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) has been advocated in assessing recurrent and residual oral cancers due to its high accuracy. Herein, we report a case with advanced buccal cancer who had received radical surgery and adjuvant radiotherapy but was suspected to have local recurrence in both CT and MRI studies performed 18 months after treatment. The corresponding FDG PET scan was also suggestive of tumor recurrence. Histopathological biopsy showed abscess formation only. And the lesion regressed completely in the follow-up PET/CT scan. The abscess was probably associated with poor wound healing and sinus track formation induced by adjuvant radiotherapy. We concluded that for advanced oral cancer patients who had received adjuvant radiotherapy, the chance of false positive PET result in local soft tissue should be watched out even years after treatment.