Unusual site of metastasis detected with FDG PET/CT in a case of recurrent rectosigmoid cancer.

Metastatic colon cancers to the oral cavity are unusual, involving a majority of the mandible rather than the oral soft tissues. We describe a rare site of gingival metastasis in a case of rectosigmoid cancer. The patient was a 74-year-old woman who developed swelling and persistent bleeding of the right mandibular gingiva after tooth extraction. A PET/CT using 18F-FDG depicted multiple metastatic lesions in the neck, lung, abdominal wall, and mandibular gingiva. Histologic study of the gingival lesion confirmed the diagnosis of gingival metastasis from colon adenocarcinoma.