Well-Differentiated Neuroendocrine Tumor-A Low b-Grade Tumor's Aggressive Course and Dismal Outcome: A Case Report.

INTRODUCTION: Incidence of well-differentiated neuroendocrine tumors (NETs) of the colon and rectum is increasing and is now approximately 1 per 100,000 in the US. NETs are either well-differentiated (indolent) or poorly differentiated (aggressive). The majority of these tumors are found incidentally during screening colonoscopies and rarely are associated with symptoms of hormonal syndrome, even during the advanced stage. Metastatic well-differentiated NETs of the colon and rectum are incurable, hard to treat, and associated with a poor prognosis and survival rates similar to colorectal adenocarcinoma survival. CASE PRESENTATION: A 56-year-old man presented to our clinic with right-sided weakness and a 40-pound weight loss during the previous 2 months. A neurologic examination was remarkable for atrophy of the right trapezius muscle and decreased strength in the right upper extremity. Imaging revealed extensive blastic and lytic lesions involving the axial skeleton, a large rectal mass, a large necrotic nodal mass extending from the left iliac region to the level of the left renal veins, and multiple necrotic liver metastasis. Liver lesion fine-needle aspiration findings were consistent with metastatic well-differentiated neuroendocrine carcinoma. DISCUSSION: This case illustrates how a low-grade tumor can have an aggressive course with poor outcomes. Metastatic well-differentiated NETs of the colon and rectum remain difficult to treat because evidence is scarce. More research is needed on this topic.