PANCREAS METASTASES FROM PAPILLARY THYROID CARCINOMA: A REVIEW OF THE LITERATURE.

Objective: Although locoregional metastases occur in 5 to 10% of patients with papillary thyroid cancer (PTC), distant metastases are rare, especially to the pancreas. Here we review the literature regarding metastases to the pancreas from PTC and present an illustrative patient.

Methods: The literature search was performed through using the PubMed database. The information regarding our illustrative case was obtained from the medical records of our institution.

Results: Since 1991, 11 cases of pancreas metastases of PTC have been reported. The average age at diagnosis was 55.3 years. There were 8 males and 3 females. Three had classic PTC histology, 2 had tall cell variant, and 2 had follicular variant. Four had T4 tumors, and 2 had T3 tumors. Seven had thyroid cancer spread to regional lymph nodes. One had distant metastasis. Pancreas metastases were diagnosed from 1 month to 13 years after primary PTC was detected; the average was 7 years. Our patient was an 84-year-old female diagnosed with PTC with a BRAFV600E mutation following total thyroidectomy. A whole-body scan after radioactive iodine (RAI) remnant ablation was negative for metastases. A pancreatic tumor was identified 2 years later on a fluorodeoxyglucose (FDG)-positron emission tomography (PET) scan. A biopsy of the tumor was histologically similar to PTC and positive for thyroglobulin, thyroid transcription factor-1, and the BRAFV600E mutation.

Conclusion: The biological reasons why PTCs metastasize to the pancreas remain to be elucidated. Older patients with non-RAI avid, FDG-PET-positive metastases, and symptoms of pancreatitis are at increased risk of this rare entity.

Abbreviations: FDG = fluorodeoxyglucose FNA = fine-need aspiration PTC = papillary thyroid cancer RAI = radioactive iodine Tg = thyroglobulin TgAb = antithyroglobulin antibodies TNM = tumor-node-metastasis.