Background Appendiceal neuroendocrine tumors (NETs) are rare in adolescents and typically an incidental finding, making preoperative diagnosis difficult. We report an exceptional case of an appendiceal NET coexisting with a parovarian cyst in an adolescent, highlighting the diagnostic challenge and management of this rare combination. Case report A 16-year-old female presented with a one-day history of migratory right lower quadrant abdominal pain and fever (38.3 °C). Examination showed right lower quadrant guarding with McBurney’s point tenderness and rebound tenderness. Ultrasound revealed a thickened appendix (max diameter 1.23 cm) and a right adnexal anechoic cyst (3.92 × 2.70 × 2.09 cm). Transumbilical single-port laparoscopy demonstrated a congested, edematous appendix with a firm 1.3-cm diameter area 3–4 cm from its base, and a well-defined 4.0 × 3.0 × 2.0 cm cystic mass within the right broad ligament. Appendectomy and parovarian cyst enucleation were performed. Pathology confirmed a well-differentiated neuroendocrine tumor (G1,WHO classification) in the appendiceal muscularis, with positive immunohistochemistry for CD-56, chromogranin A (Cg-A), cytokeratin low molecular weight (CK-LMW),Syn and Ki-67. The parovarian lesion was a serous cystadenoma. The patient recovered well with no recurrence over 7 years of follow-up. Conclusion Appendiceal NETs are rare in adolescents, often presenting as acute appendicitis, and are difficult to diagnose preoperatively. Its combination with a parovarian cyst is even rarer. Transumbilical single-port laparoscopic surgery enabled simultaneous diagnosis and treatment in this case.
Tian et al. (2026) studied this question.