Lingual tonsillar metastasis from rectal carcinoma: a rare occurrence.

A 66-year-old man presenting with sacral pain 18 months after radical transabdominal resection of rectal mucinous adenocarcinoma underwent F-FDG PET/CT cancer surveillance. Detection of multiple nodules in lingual tonsil and left neck by imaging initially suggested tonsillar squamous carcinoma (as a second primary) with spread to cervical nodes, given the rarity with which rectal carcinoma metastasizes to the head and neck. Ultimately, the tonsillar neoplasm proved to be adenocarcinoma of colorectal origin based on its shared histologic features and compatible immunostaining profile.