Primary ovarian neuroendocrine carcinoid tumors are extremely rare. However, their clinical course is good, and hence, fertility-sparing surgery is a feasible treatment option in cases of unilateral localized lesions. In this report, we present the case of a 20-year-old nulliparous woman who was diagnosed as having a primary ovarian neuroendocrine carcinoid tumor arising from a mature cystic teratoma. She underwent laparoscopic right ovarian cystectomy, and her postoperative recovery was uneventful. The patient has been under close observation over a 1-year follow-up period and has shown no evidence of tumor recurrence.

© 2023 The Author(s). Published by S. Karger AG, Basel

Neuroendocrine tumors are neoplasms that arise from cells of the endocrine and nervous systems. Their incidence has been gradually increasing in recent years owing to the development and widespread use of various diagnostic technologies. The median age at diagnosis is 55 years (range, 17–83 years) [1]. Primary ovarian carcinoid tumors are rare neoplasms, accounting for only approximately 0.1% of all ovarian neoplasms and 0.5% of all carcinoid neoplasm [2, 3]. Although neuroendocrine tumors usually occur alone, they can also occur in association with teratomas. However, this concomitant occurrence is extremely rare. Herein, we report the case of a 20-year-old woman who was diagnosed as having a neuroendocrine carcinoid tumor arising within a mature cystic teratoma.

A 20-year-old woman (gravida 0, para 0) with a body mass index of 23.16 kg/m2 visited our clinic because of abdominal discomfort. She had been experiencing the symptom for a month and had initially visited a local clinic. Transabdominal ultrasonography performed at the previous clinic revealed a right ovarian mass. Therefore, she was referred to our gynecologic clinic for further examinations.

At our clinic, she underwent transvaginal ultrasonography, which revealed a 4.0 × 4.0 × 3.5 cm heterogeneous tumor in the right ovary. Few ascites were also observed. An analysis of tumor markers revealed their levels were within the normal range: CA 125, 11.1 units/mL and CA 19-9, 29.3 units/mL. Her Anti-Mullerian hormone level was 10.80 ng/mL, and all of the preoperative laboratory test findings were normal.

The patient underwent laparotomy, which revealed that the uterus, left ovary, and both fallopian tubes were normal. Accordingly, she underwent laparoscopic right ovarian cystectomy. Macroscopic analysis revealed that the specimen, which measured 3.5 × 3.0 × 1.0 cm, was a unilocular cyst containing sebum-like materials and muddy hairs (Fig. 1). The patient showed no signs or symptoms of carcinoid syndrome. She had an uneventful postoperative recovery and was discharged on the second day after the surgery.

A 3.5 × 3.0 × 1.0 cm sized resected ovarian tumor.

Histopathological examinations revealed a neuroendocrine tumor grade 2 (carcinoid) arising from a mature cystic teratoma (Fig. 2). The tumor size was 0.4 × 0.3 × 0.3 cm and was confined to the ovary. The resection margin was clear and necrosis was not identified. The nuclear atypia was mild and no mitosis was identified. Additionally, no evidence of lymphovascular invasion was identified. Immunohistochemical analysis revealed positivity for synaptophysin and focal positivity for CD56. However, the tumor cells were negative for CDX-2. The Ki-67 index was 8.6% (Fig. 3).

Hematoxylin-eosin (H&E) stained ovarian carcinoid tumor and mature cystic teratoma component, magnification (×40).

Immunohistochemical (IHC) stained ovarian carcinoid tumor. a CD 56, magnification (×20). b Ki-67, magnification (×20). c Synaptophysin, magnification (×20). d CDX-2, magnification (×20).

After confirming the final pathologic reports, positron emission tomography-computed tomography was additionally performed. However, it revealed no evidence of other malignancies or metastasis. The patient was closely observed without any further treatment. She has been under follow-up for 1 year and has shown no evidence of recurrence. The CARE Checklist has been completed by the authors for this case report, attached as online supplementary material (for all online suppl. material, see www.karger.com/doi/10.1159/000529838).

Neuroendocrine tumors are defined as epithelial neoplasms with predominant neuroendocrine differentiation [4]. They can arise in most organs of the body. Nevertheless, they occur most commonly in the intestine and are often called carcinoid tumors. They are also commonly found in the pancreas, lungs, and gynecologic organs.

The World Health Organization (WHO) classifies neuroendocrine neoplasms as highly and moderately differentiated (G1 and G2; Ki-67 index below 20%) or poorly differentiated (G3; Ki-67 index over 20%). The new 2020 WHO classification of female genital tumors classifies neuroendocrine tumors as well-differentiated tumors (neuroendocrine tumors) and poorly differentiated carcinomas (neuroendocrine carcinomas, i.e., small cell and large cell). Moreover, the classification recommends the term “carcinoid tumor” instead of well-differentiated tumor in case of tumors arising in the aerodigestive, gynecologic, or genitourinary tract [5, 6].

Primary and metastatic ovarian neuroendocrine carcinoid tumors have similar histological growth patterns but differ in their clinical course, treatment, and prognosis [7]. Previous studies have shown that primary ovarian neuroendocrine carcinoid tumors tend to be confined to the ovary and mainly follow a benign course. However, most patients with metastatic ovarian carcinoid tumors have a low 5-year survival rate [3]. The first case of a carcinoid tumor arising in an ovarian teratoma was reported in 1939 [8]. Soga et al. [9] analyzed 329 cases of ovarian neuroendocrine tumors described in 273 previous articles. They found that the tumors tended to be larger in size, showed more frequent metastasis, and had lower 5-year survival rates if they did not arise from mature teratomas.

Owing to their rarity, no recommended treatment guidelines are currently available for primary ovarian neuroendocrine carcinoid tumors. In 2011, the Society of Gynecologic Oncology (SGO) documented guidelines for the management of neuroendocrine tumors of the gynecologic tract. For ovarian neuroendocrine carcinoid tumors, surgical treatment is commonly performed and ranges from fertility-sparing surgery to debulking operation, depending on the disease distribution. However, no adjuvant therapy is currently available for these tumors [10].

In conclusion, a primary ovarian carcinoid tumor arising in a mature cystic teratoma has a good clinical outcome. Therefore, fertility-sparing surgery could be a treatment option in cases of unilateral ovarian lesions. Nevertheless, further documentation of cases and clinical outcomes is needed to establish a standard treatment strategy for these rare tumors.

The case report was conducted according to the guidelines of the Declaration of Helsinki. This study protocol was reviewed and approved by the Institutional Review Board of Inje University Haeundae Paik Hospital (IRB No. 2022-08-019). Written informed consent was obtained from the patient for publication of this case report and any accompanying images.

The authors have no conflicts of interest to declare.

There was no funding involved in the development of this case review.

Dr. Eunhyun Lee offered initial idea and conception. Dr. Minjeong Park wrote original draft. All of the authors wrote the final article.

All data generated or analyzed during this study are included in this article and its online supplementary material. Further inquiries can be directed to the corresponding author.

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