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

Abstract

Background: 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.

Case report: 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).

Conclusion: 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.

Keywords: Endoscopic ultrasound-guided fine needle aspiration; neoplasm metastasis; pancreatic neoplasms; thyroid cancer–papillary.

Figure 1.

(A) Endoscopic ultrasound showed a well-circumscribed cystic lesion measuring 4.0 × 2.8 cm in the uncinate process and a mural nodule (asterisk) measuring 2.6 × 2.2 cm. (B) A neoplastic thrombus (arrow) was partially obstructing the superior mesenteric vein. (C) The mural nodule was punctured by endoscopic ultrasound-guided biopsy (arrowhead).

Figure 2.

(A) Histologic findings of pancreatic metastasis from papillary thyroid carcinoma demonstrated a tumor consisting of cuboidal cells with irregular membrane, vacuolated cytoplasm, nuclear grooves, oval nuclei with granular chromatin, and no mitotic activity. A papillary arrangement and fibrovascular cores with pseudoinclusions were detected in the pancreatic tissue (hematoxylin and eosin stain, magnification ×400). Neoplastic cells showed intense immunoreactivity for (B) thyroglobulin (magnification ×200), (C) thyroid transcription factor 1 (magnification ×100), and (D) cytokeratin 7 (magnification ×100). Thyroglobulin and cytokeratin 7 were positive for membranous and cytoplasmic immunoreactivity. Thyroid transcription factor 1 indicates nuclear positivity.

Figure 3.

Contrast-enhanced axial abdominal computed tomography scan showed a 4.9 × 3.5 × 2.8-cm pancreatic cystic lesion in the uncinate process with a mural nodule in the cystic lumen (arrow).