# Late Pancreatic Metastasis From Papillary Thyroid Carcinoma Diagnosed by Endoscopic Ultrasound-Guided Tissue Acquisition

## TL;DR

A patient with papillary thyroid cancer developed a rare pancreatic metastasis 11 years after treatment, diagnosed via endoscopic ultrasound and managed with radiotherapy.

## Contribution

This case highlights the rare occurrence of pancreatic metastasis from thyroid cancer and the diagnostic utility of endoscopic ultrasound-guided biopsy.

## Key findings

- Pancreatic metastasis from papillary thyroid carcinoma was diagnosed 11 years after initial treatment.
- Endoscopic ultrasound-guided biopsy confirmed metastasis using thyroglobulin and thyroid transcription factor 1 markers.
- The patient was treated with stereotactic body radiotherapy due to non-iodine-avid tumor characteristics.

## Abstract

Papillary thyroid carcinoma, the most common differentiated thyroid cancer, has an indolent clinical course and a good prognosis. Metastases to the gastrointestinal tract account for <1% of all distant metastases, and the pancreas is an extremely rare site for metastasis from thyroid cancer.

We report the case of a patient who developed a pancreatic metastasis from a classic variant papillary thyroid carcinoma 11 years after total thyroidectomy, cervical lymphadenectomy, and radioactive iodine ablation. The patient experienced increased thyroglobulin levels, and abdominal computed tomography scan revealed a lesion in the uncinate process of the pancreas. Tissue samples obtained by endoscopic ultrasound-guided biopsy were positive for thyroglobulin and thyroid transcription factor 1. Because the patient was not a candidate for surgery, the metastatic lesion was not iodine-avid, and tyrosine kinase inhibitors could not be offered because of tumor-related symptoms, the patient was treated with stereotactic body radiotherapy only. The patient died almost 2 years after the diagnosis of metastatic papillary thyroid carcinoma to the pancreas (13 years after total thyroidectomy for the primary cancer).

If pancreatic lesions are discovered during regular follow-up of patients who have previously been treated for papillary thyroid carcinoma, pancreatic metastasis must be considered, and imaging procedures other than whole-body iodine scintigraphy are required. Histopathology and iodine avidity will define the best therapeutic strategy. Radioactive iodine ablation should be considered for iodine-avid metastases, and surgery or tyrosine kinase inhibitors are promising options for non-iodine–avid lesions.