A Sunflower in the Terminal Ileum: An Incidental Neuroendocrine Tumor on Surveillance Colonoscopy

CASE REPORT An asymptomatic 48-year-old woman without a personal or family history of cancer underwent surveillance high-definition white-light colonoscopy 3 years after resection of a 20 mm sigmoid tubulovillous adenoma. Given her advanced adenoma at a young age, there was concern for a possible hereditary cancer syndrome, and terminal ileal intubation, a marker of complete colonoscopy, was performed. This revealed a solitary, well-circumscribed 6 mm sessile polypoid lesion in the terminal ileum. The lesion caused radial villous displacement, suggestive of submucosal involvement with mass effect, producing a sunflower appearance (Figure 1). Accordingly, endoscopic resection was deferred and biopsies were obtained.Figure 1.: Endoscopic view of a 6 mm sessile polypoid lesion with a smooth, cloud-like surface, located 2 cm from the ileocecal valve. The lesion displaces surrounding villi, creating a distinctive sunflower pattern.Histopathology demonstrated a well-differentiated neuroendocrine tumor (NET) with submucosal invasion (Figures 2 and 3). The Ki-67 index was 2%, consistent with a WHO Grade 1 tumor. Serum chromogranin A was 27 ng/mL (reference range: 0–187 ng/mL), and 24-hour urinary 5-hydroxyindoleacetic acid was 4 mg/d (reference range: 0–15 mg/d). 64Cu-DOTATATE positron emission tomography and magnetic resonance enterography did not identify disease. She underwent robot-assisted right hemicolectomy revealing a 7 mm tumor (Figure 4) with one positive lymph node. This case highlights high nodal metastasis rates for ileal NETs, which underpin National Comprehensive Cancer Network recommendations for surgical resection with regional lymphadenectomy for locoregional ileal NETs.1,2Figure 2.: Ileal lesion biopsy demonstrating tumor cells with monotonous round-to-oval nuclei, salt-and-pepper chromatin, and moderate eosinophilic granular cytoplasm, consistent with a well-differentiated neuroendocrine tumor (hematoxylin and eosin, ×600).Figure 3.: Ileal lesion biopsy demonstrating tumor cells confined to the submucosa of the small intestine (hematoxylin and eosin, ×100).Figure 4.: Gross specimen from a robot-assisted right hemicolectomy showing a 7 mm terminal ileum neuroendocrine tumor (black arrow), confirmed histologically.DISCLOSURES Author contributions: A. Ahmed: Conception and design, acquisition of data, analysis and interpretation of data, drafting and reviewing the work. T. Hajarat and A. Sharma: Analysis and interpretation of data, drafting and reviewing the work. A. Ahmed is the article guarantor. Financial disclosure: None to report. Informed consent was obtained for this case report.