Initial Report of an Intradural Extramedullary Metastasis of a Pancreatic Neuroendocrine Tumor to the Cervical Spine: A Case Report and Review of the Literature

Background

Pancreatic neuroendocrine tumors (pNETs) are known to frequently metastasize to the liver and lymphatics; however, metastasis to the spine is exceedingly rare. We report the first case of an intradural, extramedullary pNET metastasis to the upper cervical spine.

Case Description

A 75-year-old Hispanic male patient with history of stage IV pNET with metastasis to the liver and lymph nodes and new-onset lymphadenopathy seen on CT of the chest was found on positron emission tomography scan to have a lesion in the cervical spine. The patient was neurologically intact on physical examination, yet given the patient's medical history, magnetic resonance imaging of the cervical spine was performed, revealing a right-sided intradural, extramedullary mass at the C1–C2 level with associated mass effect on the spinal cord, likely representing a schwannoma. Due to the tumor size, mass effect, and the need for definitive tissue diagnosis, a partial C1–C2 laminectomy with intradural resection of the tumor was performed. The histology was consistent with the patient's known pNET.

Conclusions

As treatment for pNETs has evolved, there has been a surge in unique presentations of systemic well-differentiated pNETs being reported. It is vital that patients diagnosed with pNET be monitored for metastases, and when discovered, treated promptly.

Introduction

Neuroendocrine tumors are a diverse group of malignancies defined as epithelial neoplasms with predominant neuroendocrine differentiation.¹ These tumors arise from neuroendocrine cells distributed throughout the body; however, two thirds of these tumors are of pancreatic or gastrointestinal origin, with pancreatic or rectal origin entailing a worse prognosis.² Although pancreatic neuroendocrine tumors (pNETs) have a relatively low incidence of 3 cases per million, they account for about 10% of malignant pancreatic cancers and have shown a steady increase in incidence over the past 3 decades.^3,4

pNETs frequently metastasize to the liver, lymphatics, and less frequently to the peritoneum and lungs.⁵ Metastasis to the spine is exceedingly rare and can lead to spinal cord compression through extramedullary spread of tumor. Although the majority of reported cases of spinal cord compression from metastatic pNET lesions are characterized by extradural spread from a vertebral body lesion, only one other case of an intradural, extramedullary pNET metastasis has been reported to our knowledge in the upper thoracic spine.⁶ Here we report a 75-year-old male patient with a previous history of stage IV pNET treated with lanreotide injections who presented with an incidentally discovered intradural, extramedullary mass in the cervical spine. The patient was successfully managed with surgical resection of this solitary mass, which was found to be a pNET metastasis, and he was continued on lanreotide injections. To our knowledge, this is the first reported case of an intradural, extramedullary metastasis of a pNET to the upper cervical spine. We discuss the perioperative management as well as a brief review of the literature in regard to pNET spine metastasis.