Rectal carcinoma metastatic to the thyroid gland.

Clinically evident metastases to the thyroid gland are rarely found antemortem. A case of a 59-year-old woman with a history of rectal carcinoma, who presented with low back pain and a mass in the right lobe of her thyroid gland, is presented. The tumour of the thyroid was found to be metastatic adenocarcinoma from her previous rectal cancer. Other synchronous metastases were noted in her lumbar spine and kidneys. The clinical finding of metastases to the thyroid gland is rare, particularly from a colorectal primary. One must consider, however, the possibility of a tumour of the thyroid gland representing a secondary malignancy in any patient with a prior history of cancer.