Pancreatic Metastasis of Papillary Thyroid Carcinoma Diagnosed by Endoscopic Ultrasound and Fine-Needle Aspiration

Abstract

Introduction: The National Cancer Institute estimates that in 2012 the new number of new thyroid cancer cases reported will be approximately 56,000 with 1,780 expected deaths. There are four distinct subtypes of thyroid cancer: papillary, follicular, medullary, and anaplastic, with papillary being the most common subtype. Associated metastatic disease appears in about 5% of these patients with the most common site of metastasis being the lung and bone. Metastatic disease to the pancreas is extremely rare, with only a few cases reported. Case Report: A 61-year-old female, with a history of papillary thyroid carcinoma treated by thyroidectomy and radioiodine ablation (RAI), presents for evaluation for persistent elevation of her thyroglobulin level. A positron emission tomography scan revealed a 3-cm heterogeneously enhancing lesion in the body of the pancreas. At time of presentation the patient denied any jaundice, abdominal pain, nausea, vomiting, back pain, or weight loss. On physical examination the patient was anicteric, with no abdominal tenderness or masses. Patient underwent an endoscopic ultrasound (EUS) for further evaluation revealing a round, hypoechoic well-defined mass in the pancreatic body, approximately 3.6 x 3.4 cm. The pancreatic duct, upstream from the lesion, was dilated to 5 mm. Fine needle aspiration of the mass using a trans-gastric approach was performed. Immunohistochemical staining showed the neoplastic cells to be positive for TTF-1, thyroglobulin, CK19, and CK7. CK20, monoclonal CEA, and the neuroendocrine markers were negative. CA 19-9 was focally positive. Cytology was positive for the presence of malignant cells and findings were consistent with metastatic thyroid carcinoma to the pancreas. Discussion: This case illustrates a very rare presentation of metastatic disease. For diagnosis, EUS is now recognized as the most sensitive tests for the detection of both primary and metastatic lesions of the pancreas. Also observed in our case is the utilization of EUS-FNA with sensitivity for detecting malignancy ranging from 75-90%. This technique is superior to that of CT-guided FNA as well as endoscopic retrograde pancreatography (ERP). Our case highlights the utility of EUS, EUS-FNA, and immunohistochemical staining to obtain a tissue diagnosis in suspected pancreatic metastasis.