Pancreatic Metastasis Arising from a BRAFV600E-Positive Papillary Thyroid Cancer: The Role of Endoscopic Ultrasound-Guided Biopsy and Response to Sorafenib Therapy

Background: Lungs and bones are the most common sites for distant metastases from papillary thyroid cancer (PTC). Metastases to the pancreas are extremely rare. Here we present a man with pancreatic metastases from PTC, report our experience with sorafenib therapy, and discuss the role of endoscopic ultrasound (EUS)-guided biopsy in its diagnosis. Patient Findings: A 56-year-old man underwent total thyroidectomy, right-modified neck dissection, and radioactive iodine (RAI) remnant ablation for PTC at age 47 years (in 2002). Between 2002 and 2007, he had three more neck surgeries, two RAI therapies, and external beam radiotherapy for persistent and subsequently metastatic PTC. In 2008, a computed tomography/positron emission tomography (CT/PET) scan showed an 18F-fluorodeoxyglucose (FDG)-avid pancreatic focus. Magnetic resonance imaging (MRI) revealed a pancreatic nodule at the same location. An EUS-guided biopsy confirmed the diagnosis of pancreatic metastasis from PTC, and molecular studies showed positive BRAF V600E mutation. He was treated with sorafenib for 6 months. Although a lung CT scan done 2 months after initiation of sorafenib suggested stability of the disease, MRI studies done at 3 and 6 months showed clear progression with an increase in the size of the lung and pancreatic metastases. Subsequently, he developed liver, bone, and omental metastases. He died in July 2011, 9 years and 8 months after the initial diagnosis of PTC and 20 months after discovery of the pancreatic metastasis. Summary: A middle-aged man with PTC developed lung metastases despite multiple surgeries and RAI therapies. Seven years after the initial diagnosis, a pancreatic metastasis was accidentally discovered. Both the metastasis and the primary thyroid tumor are positive for BRAF V600E mutation. The lung and pancreatic metastases progressed while the patient was receiving sorafenib for 6 months, and the patient died 20 months after diagnosis of pancreatic metastasis. Conclusion: PTC rarely metastasizes to the pancreas. In this patient, an FDG PET scan and EUS-guided biopsy played important roles in the diagnosis. PTC metastases to the pancreas usually occur in otherwise advanced disease. In the patient presented here, sorafenib may have slowed disease progression but the overall utility of tyrosine kinase inhibitors in pancreatic metastases from PTC is not clear.