Beyond Gastrointestinal Bleed: Unexpected Discovery of Low-Grade Appendiceal Mucinous Neoplasm

CASE REPORT An 81-year-old woman underwent colonoscopy for evaluation of a 3-month episode of mild hematochezia. She remained hemodynamically stable without anemia or other gastrointestinal symptoms. Apart from moderate-to-severe diverticular disease in the left colon, colonoscopy revealed a bulging appendiceal orifice (Figure 1) draining thick mucinous discharge (Figure 1) raising concern for an underlying mucinous appendiceal neoplasm. Biopsy obtained at the appendix revealed normal colonic mucosa. A follow-up contrast-enhanced computed tomography scan demonstrated a prominent, low-attenuation nodule at the base of the appendix measuring 2.1 cm (Figure 1), concerning of potential appendiceal neoplasm. Given the risk of malignant transformation and potential perforation, the patient underwent ileocecal resection. Surgical pathology revealed a 9.3-cm appendix with low-grade mucinous neoplasm extending along the entire appendix (hematoxylin and eosin, orig. mag. ×10 and ×40) (Figure 1). Surgical margins were clear, and no lymph node involvement was identified. This highlights the importance of recognizing subtle endoscopic features suggestive of appendiceal neoplasia, even in the absence of overt symptoms or biopsy-confirmed pathology. Early identification and surgical management are crucial to prevent complications including pseudomyxoma peritonei, perforation, or malignant transformation in these cases.Figure 1.: (A) Bulging appendiceal orifice. (B) Appendiceal orifice with thick mucinous discharge. (C) Computed tomography of the abdomen and pelvis demonstrating a prominent low-density nodule at the base of the appendix measuring 2.1 cm. (D) Low-power histopathology of the appendix showing features consistent with low-grade appendiceal mucinous neoplasm (hematoxylin and eosin, ×10). (E) High-power view demonstrating mucinous epithelium with low-grade cytologic atypia (hematoxylin and eosin, ×40).DISCLOSURES Author contributions: R. Worapongpaiboon reviewed the case and drafted the manuscript. H. Bedi assisted in manuscript preparation and revision. K. Salimian provided pathological interpretation and figures. S. Ngamruengphong supervised the work, the corresponding author and is the article guarantor. Financial disclosure: S. Ngamruengphong has served as a consultant for Boston Scientific, Olympus, Neptune Medical, Fujifilm, and Cook Medical. Others are none to report. Informed consent was obtained for this case report.