{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,19]],"date-time":"2026-03-19T13:08:20Z","timestamp":1773925700436,"version":"3.50.1"},"reference-count":16,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,3,19]],"date-time":"2026-03-19T00:00:00Z","timestamp":1773878400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Capital Health Science and Technology Development Special Project","award":["2024-2-1025"],"award-info":[{"award-number":["2024-2-1025"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background: Primary peritoneal carcinoma (PPC) is an uncommon malignancy typically diagnosed in postmenopausal women, accounting for less than 1% of all gynecologic cancers. Its occurrence in adolescents is extremely rare. We present a case of a 16-year-old female with low-grade serous carcinoma (LGSC) arising from the anterior rectal peritoneum, highlighting diagnostic challenges and therapeutic considerations. Case Presentation: A 16-year-old girl presented with a 7-day history of lower abdominal pain. Ultrasound revealed an 8 cm mixed cystic\u2013solid pelvic mass anterior to the rectum. Laboratory tests showed elevated CA-125 (106 U\/mL). Exploratory laparotomy demonstrated an 8 cm solid mass attached to the anterior rectal wall, extending into the right mesorectum with peritoneal nodules at the bladder reflection. The uterus and adnexa appeared grossly normal. Frozen section analysis revealed adenocarcinoma with psammoma body formation. Histopathology and immunohistochemistry confirmed low-grade serous carcinoma: PAX8(+), WT1(+), CK7(+), ER(60%), PR(40%), CK20(\u2013), and P53 wild-type. Peritoneal washings contained rare malignant cells. Postoperatively, the patient underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy, and omentectomy. Final pathology confirmed low-grade serous carcinoma involving the anterior rectal wall, bilateral adnexal surfaces, and peritoneum. She completed six cycles of adjuvant chemotherapy (paclitaxel + carboplatin, TC regimen). No recurrence was observed during follow-up. Conclusions: This case underscores the importance of considering PPC in the differential diagnosis of pelvic masses in young females, even when the ovaries appear normal.<\/jats:p>","DOI":"10.3390\/jcm15062343","type":"journal-article","created":{"date-parts":[[2026,3,19]],"date-time":"2026-03-19T08:54:37Z","timestamp":1773910477000},"page":"2343","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Primary Peritoneal Low-Grade Serous Carcinoma in a 16-Year-Old Female: A Case Report"],"prefix":"10.3390","volume":"15","author":[{"given":"Yuang","family":"An","sequence":"first","affiliation":[{"name":"Department of Ultrasound, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yijian","family":"Fan","sequence":"additional","affiliation":[{"name":"Department of Ultrasound, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yu","family":"Xia","sequence":"additional","affiliation":[{"name":"Department of Ultrasound, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1146\/annurev-pathol-020712-163949","article-title":"Origin and pathogenesis of pelvic (ovarian, tubal, and primary peritoneal) serous carcinoma","volume":"9","author":"Nik","year":"2014","journal-title":"Annu. Rev. Pathol. Mech. Dis."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"viii8-12","DOI":"10.1093\/annonc\/mdx445","article-title":"The new classifications of ovarian, fallopian tube, and primary peritoneal cancer and their clinical implications","volume":"28","author":"Duska","year":"2017","journal-title":"Ann. Oncol."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Otsuka, I. (2023). Primary Retroperitoneal Carcinomas: New Insights into Pathogenesis and Clinical Management in Comparison with Ovarian Carcinomas and Carcinoma of Unknown Primary. Cancers, 15.","DOI":"10.3390\/cancers15184614"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1016\/j.critrevonc.2009.10.003","article-title":"Serous papillary peritoneal carcinoma: Unknown primary tumour, ovarian cancer counterpart or a distinct entity? A systematic review","volume":"75","author":"Pentheroudakis","year":"2010","journal-title":"Crit. Rev. Oncol. Hematol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1007\/s13193-022-01612-9","article-title":"Histopathological Evaluation and Molecular Diagnostic Tests for Peritoneal Metastases with Unknown Primary Site\u2014A Review","volume":"14","author":"Bhatt","year":"2023","journal-title":"Indian J. Surg. Oncol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1186\/s13244-023-01417-6","article-title":"Primary and secondary tumours of the peritoneum: Key imaging features and differential diagnosis with surgical and pathological correlation","volume":"14","author":"Forn","year":"2023","journal-title":"Insights Imaging"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"420","DOI":"10.1097\/PAT.0b013e328348a6e7","article-title":"Morphological subtypes of ovarian carcinoma: A review with emphasis on new developments and pathogenesis","volume":"43","author":"McCluggage","year":"2011","journal-title":"Pathology"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1093\/jnci\/92.3.205","article-title":"New guidelines to evaluate the response to treatment in solid tumors","volume":"92","author":"Therasse","year":"2000","journal-title":"J. Natl. Cancer Inst."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"762","DOI":"10.1016\/j.ygyno.2007.02.020","article-title":"Papillary serous carcinoma in ovaries of normal size: A clinicopathologic study of 20 cases and comparison with extraovarian peritoneal papillary serous carcinoma","volume":"105","author":"Choi","year":"2007","journal-title":"Gynecol. Oncol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"e89","DOI":"10.5114\/pjr.2023.125027","article-title":"Diagnosis and treatment of peritoneal carcinomatosis\u2014A comprehensive overview","volume":"88","author":"Szadkowska","year":"2023","journal-title":"Pol. J. Radiol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1102\/1470-7330.2011.0016","article-title":"Ct, mri and pet imaging in peritoneal malignancy","volume":"11","author":"Patel","year":"2011","journal-title":"Cancer Imaging"},{"key":"ref_12","first-page":"991","article-title":"Primary peritoneal and ovarian cancers: An epidemiological comparative analysis","volume":"21","author":"Grant","year":"2010","journal-title":"Cancer Causes Control"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1753","DOI":"10.1093\/jnci\/djae151","article-title":"Incidence of peritoneal cancer after oophorectomy among brca1 and brca2 mutation carriers","volume":"116","author":"Narod","year":"2024","journal-title":"J. Natl. Cancer Inst."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1479","DOI":"10.1038\/s41416-022-01897-1","article-title":"Clinical characteristics and molecular aspects of low-grade serous ovarian and peritoneal cancer: A multicenter, observational, retrospective analysis of MITO Group (MITO 22)","volume":"127","author":"Musacchio","year":"2022","journal-title":"Br. J. Cancer"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1511","DOI":"10.1016\/S0002-9440(10)63708-X","article-title":"Ovarian tumorigenesis: A proposed model based on morphological and molecular genetic analysis","volume":"164","author":"Shih","year":"2004","journal-title":"Am. J. Pathol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1016\/S1470-2045(20)30591-X","article-title":"Objective responses to first-line neoadjuvant carboplatin-paclitaxel regimens for ovarian, fallopian tube, or primary peritoneal carcinoma (ICON8): Post-hoc exploratory analysis of a randomised, phase 3 trial","volume":"22","author":"Morgan","year":"2021","journal-title":"Lancet Oncol."}],"container-title":["Journal of Clinical Medicine"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/6\/2343\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,19]],"date-time":"2026-03-19T09:29:49Z","timestamp":1773912589000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/6\/2343"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,19]]},"references-count":16,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2026,3]]}},"alternative-id":["jcm15062343"],"URL":"https:\/\/doi.org\/10.3390\/jcm15062343","relation":{},"ISSN":["2077-0383"],"issn-type":[{"value":"2077-0383","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,19]]}}}