{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T09:39:55Z","timestamp":1777887595118,"version":"3.51.4"},"reference-count":11,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T00:00:00Z","timestamp":1777593600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Oncol."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Case report<\/jats:title>\n                    <jats:p>A 16-year-old female presented with a one-day history of migratory right lower quadrant abdominal pain and fever (38.3\u00a0\u00b0C). Examination showed right lower quadrant guarding with McBurney\u2019s point tenderness and rebound tenderness. Ultrasound revealed a thickened appendix (max diameter 1.23\u00a0cm) and a right adnexal anechoic cyst (3.92 \u00d7 2.70 \u00d7 2.09\u00a0cm). Transumbilical single-port laparoscopy demonstrated a congested, edematous appendix with a firm 1.3-cm diameter area 3\u20134 cm from its base, and a well-defined 4.0 \u00d7 3.0 \u00d7 2.0\u00a0cm 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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>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.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fonc.2026.1806034","type":"journal-article","created":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T04:18:18Z","timestamp":1777609098000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case report of an appendiceal neuroendocrine tumor (carcinoid) combined with a parovarian cyst in an adolescent"],"prefix":"10.3389","volume":"16","author":[{"given":"Yali","family":"Tian","sequence":"first","affiliation":[{"name":"Department of Pediatric Surgery, Binzhou People\u2019s Hospital","place":["Binzhou, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ying","family":"Wu","sequence":"additional","affiliation":[{"name":"Department of Pediatric Surgery, Binzhou People\u2019s Hospital","place":["Binzhou, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fang","family":"Hao","sequence":"additional","affiliation":[{"name":"Department of Pediatric Surgery, Binzhou People\u2019s Hospital","place":["Binzhou, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xujian","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology, Children\u2019s Hospital Affiliated to Shandong University","place":["Jinan, China"]},{"name":"Department of Anesthesiology, Jinan Children\u2019s Hospital","place":["Jinan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Meng","family":"Kong","sequence":"additional","affiliation":[{"name":"Department of Pediatric Surgery, Children\u2019s Hospital Affiliated to Shandong University","place":["Jinan, China"]},{"name":"Department of Pediatric Surgery, Jinan Children\u2019s Hospital","place":["Jinan, 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