Thyroid Metastasis From Caecal Adenocarcinoma.

The thyroid is a rare site of colorectal metastasis, comprising 0.1% of the surgical case series. A 62-year-old woman with caecal adenocarcinoma and previously surgically resected lung and liver metastases presented incidentally with a right thyroid nodule, which had grown and become symptomatic. Imaging revealed the nodule to have extracapsular spread, and cytology demonstrated metastatic adenocarcinoma. The patient underwent a technically challenging right thyroidectomy and neck dissection, with the final histopathological review demonstrating metastatic adenocarcinoma from a colorectal primary. The patient has subsequently undergone adjuvant radiotherapy. This case highlights an uncommon source of metastasis to the thyroid, which may aid clinicians to recognise and initiate treatment. It also highlights the technical challenges of performing surgery in such cases.