A Rare Case of Metastatic Poorly Differentiated Neuroendocrine Tumor Arising From the Sigmoid Colon in an Active Duty Service Member

ABSTRACT Neuroendocrine tumors (NET) are rare malignancies that contain neural and endocrine cells with a median age of diagnosis of 63 years. NETs are typically located in the gastrointestinal (GI) tract, the pancreas, or the lungs. Within the GI tract, the most common locations for NETs are the small bowel, appendix, or rectum. They are often asymptomatic and found incidentally on imaging or during procedures. NETs arising from the left side of the colon are very uncommon. While most NETs are well-differentiated by histology and are slow growing, 7% are poorly differentiated and usually progress rapidly. While rare, it is vital to be vigilant for this reason We present such a case of poorly differentiated metastatic NET of the sigmoid colon in a young active duty service member.