15-Year-Old Patient with an Unusual Alpha-Fetoprotein-Producing Sertoli-Leydig Cell Tumor of Ovary

Ovarian Sertoli-Leydig cell tumors (SLCTs) are extremely rare ovarian sex-cord stromal tumors. Alpha-fetoprotein (AFP) production by SLCTs is a rare event generally linked to the presence of hepatocytes or intestinal mucinous epithelium as heterologous elements. We report here a case of a 15-year-old female complaining about abdominal pain, constipation, and spaniomenorrhea with high level of serum AFP leading to a clinical suspicion of malignant germ cell tumor. Final histopathological diagnosis was a moderately differentiated Sertoli-Leydig cell tumor of the ovary with alpha-fetoprotein-producing cells without hepatocytic or intestinal epithelium differentiation. NGS analysis showed mutation in DICER1 gene. SLCTs occur in patients at any age with a mean age of 25 years. The presence of alpha-fetoprotein-producing cells is an important tool in the differential diagnosis of germ cell tumors and challenging in this case of SLCT because of its rarity in this context. An adequate sampling and exhaustive immunohistochemical analyses are mandatory to make the correct differential diagnosis and confirm the presence of alpha-fetoprotein-producing cells and also define the differentiation because of therapeutic strategies between conservative surgery and/or chemotherapy.


Introduction
Ovarian Sertoli-Leydig cell tumors (SLCTs) are rare mixed-sexcord stromal tumors of the ovary, concerning less than 0.5% of all primary ovarian neoplasms [1]. It affects all age groups of patients, with 75% detected in young women less than 30 years (mean age of 25 years) and less than 10% detected after menopause. Most of the cases (97%) are unilateral and confined to the ovary at the diagnosis (FIGO stage I) [2].
Due to testicular-like tumor cell types (Sertoli and Leydig cells) producing androgens, clinical signs and symptoms such as irregular menstruation and virilization are seen in 50% of cases with occasional patients presenting estrogenic manifestations [3,4]. Usually, patients return to normal hormone levels after surgical excision.
Moderately and poorly differentiated forms are the most common types and may contain heterologous elements such as hepatocytes, intestinal type mucinous epithelium, cartilage, and skeletal muscle.
SLCTs are associated with somatic and germline mutations of DICER1 and FOXL2 [5].
The overall prognosis is favorable but is related to the degree of differentiation and stage of the tumor [2].
We report here a case of ovarian SLCT in a 15-year-old female with elevated testosterone and alpha-fetoprotein (AFP) without specific differentiation or heterologous elements and review SLCTs producing AFP reported in the literature.

Material and Methods
Tissue was obtained at the surgery time and fixed in buffered 10% formalin. All sections were stained with routine hematoxylin-eosin saffron.
Slides and blocks were sent at Institut Curie (Paris) for complementary studies such as NGS analysis for DICER1 mutation and OCT3/4, SALL4 immunostainings.
A literature review was made on Pubmed using the keywords: "Sertoli tumor," "Sertoli-leydig tumor," and "alphafoetoprotein." We searched for cases of SLCTs with elevated    Case Reports in Obstetrics and Gynecology AFP levels and associated with specific differentiation and/or heterologous elements or not; in order to understand the origin of AFP production. Only English articles were included. We treated especially the recent largest literature review published by AL-Hussaini et al. made an update with new case reports found on Pubmed using the PRISMA flow diagram for updated systematic reviews [6,7] (Figure 1).

Case Presentation
A 15-year-old female presenting complaints of abdominal pain, constipation, and spaniomenorrhea for three months was referred to the department of gynecology. The patient reported menarche at the age of 11 with regular menstrual cycles. No familial history of malignancy was reported. At the physical examination, no abnormalities were noted. Axial T2-weighted magnetic resonance imaging (MRI) showed a right adnexal mass measuring 7:8 × 6:4 × 7 cm. Left ovary and uterus were unremarkable. There were not any ascites ( Figure 2). Elevated testosterone (66, 5 pmol/L; normal range 3.0-37, 0) and AFP (117 ng/mL; normal range at 14) were noted. Other ovarian tumor markers including beta-human chorionic gonadotropin (β-HCG), CA 125, CA 19-9, and carcinoembryonic antigen (CEA) remained negative.
A germ cell tumor (dysgerminoma and yolk sac tumor) or a pure sex cord tumor (juvenile granulosa cell tumor) was clinically suspected.
Laparoscopic right salpingo-oophorectomy was carried out after a multidisciplinary oncological concertation. No adverse event was encountered after surgery.
Macroscopic examination revealed a right ovary totally replaced by a tumor measuring 8, 5 × 5 × 4, 5 cm with an intact capsule ( Figure 3). Gross sections demonstrated a brownish solid aspect with fibrous areas and partially cystic zones filled with clear yellow fluid.
Microscopic examination showed a tumor displaying a multinodular pattern with heterogenous cellularity and an intact capsule.
Cellular zones were composed of Sertoli-like spindle cells having scant-to-moderate amount of cytoplasm with round   3 Case Reports in Obstetrics and Gynecology to oval nuclei and 0 to 1 little nucleoli. At the periphery of these areas, there were clusters of larger cells with a pale foamy cytoplasm and oval nuclei. There were also rare isolated cells with abundant clear cytoplasm.
Tumoral cells showed moderate atypia with a mitotic rate less than 2 mitoses per 10 high-power fields.
The stroma containing the tumor was characterized by edema, vascularization, and fibro-sclerotic changes ( Figure 4).
There was one focal zone of retiform pattern less than 1 mm composed of larger cells ( Figure 5).
On immunohistochemical studies, Sertoli-like cells showed nuclear staining for WT1, moderately positive cytoplasmic staining for inhibin and weakly positive nuclear and cytoplasmic staining for calretinin.
The Leydig-like cells demonstrated a strong positivity for inhibin and a moderate positivity for cytoplasmic calretinin staining.
Rare isolated cells with abundant clear cytoplasm were positive for cytokeratins (AE1AE3), AFP, and alpha-1antitrypsin suggesting a hepatocytic differentiation but they did not display any staining for Cytokeratin7 and HepPar1 excluding a complete mature hepatocytic differentiation ( Figure 6).
Based on the above findings, we concluded to moderately differentiated SLCT with alpha-fetoprotein-producing cells without heterologous elements or specific differentiation (FIGO stage IA). No adjuvant therapy was given.
The patient reported spontaneous menstruation a few days after surgery with improvement of clinical symptoms.
AFP returns to normal range two months after tumor resection. A regular follow-up was planned, and no complaints or clinically relevant abnormalities were noted six months after surgery.

Discussion
We, hereby, report a rare case of SLCT of moderate differentiation with an unusual AFP-producing cell component and a clinical suspicion of germ cell tumor. In their large literature review, Al-Hussaini et al. reported approximately 50 cases of SLCTs with alpha-fetoprotein-producing component in the last 50 years [6].
We compare our case to these cases and to new case reports since this publication to understand the origin of AFP-producing cells (Table 1) [6,[8][9][10][11].
SLCTs present, in 40-60% of the cases, with signs and symptoms of hormone production related to the androgenic activity such as virilization, hirsutism, voice hoarseness, abnormal hair distribution, clitoromegaly, menstrual abnormalities, anovulation, and infertility. These elements are helpful to clinicians to make the differential diagnosis between epithelial and germ cell tumors [4]. SLCTs represent 20% of ovarian sex cord-stromal tumors in children [12].  Case Reports in Obstetrics and Gynecology Laboratory tests are disturbed with elevated plasma testosterone at least 2.5 times its normal value. Elevated serum AFP levels are uncommon in SLCTs, and the significance of this production remains to be elucidated [12]. Tumors that are classically characterized by elevated AFP serum levels include yolk sac tumor, hepatocellular carcinoma, hepatoblastoma, and adenocarcinoma with hepatoid differentiation. Rare reports of female genital tract tumors with serum AFP elevation that concern ovarian neoplasms other than yolk sac tumor are immature teratoma, serous carcinoma, clear cell carcinoma, hepatoid carcinoma, mucinous carcinoma, and carcinosarcoma [6].
In normal situation, AFP is a major fetal plasma component produced in early fetal period by yolk sac, liver, and upper gastrointestinal tract. Its production declines rapidly in a few months after birth and reaches nearly undetectable levels for less than 10 ng/mL [12,13]. Serum AFP is generally used as tumor marker of hepatocellular carcinomas in Case Reports in Obstetrics and Gynecology adults and germ cell tumors in young patients. Elevated AFP is less frequently identified in lung, oesophagus, stomach, and pancreas carcinomas [14]. The origin of AFP-producing cells in SLCTs remains to elucidate. Several hypotheses have been reported defining AFP-producing cells to be Sertoli-Leydig-like cells, or endodermal derived cells such as hepatocytes or gastrointestinal type mucinous epithelia [15]. Based on the literature review of Al-Hussaini et al., we treated the 29 articles with a total of 46 reported cases.
26 cases presented heterologous elements with AFP production linked to the presence of intestinal-type mucinous epithelium or hepatocytes [15][16][17]. In their case report, Mooney et al. explained that hepatocytes and Leydig cells have morphological similarity and are closely located to each one [18].
Thus, AFP immunostaining is mandatory to distinguish these cells; Leydig cell is showing a fine cytoplasmic granular positivity for AFP and true hepatocytes displaying a stronger positivity [18].
In the other 20 cases, like our current case with no specific differentiation or heterologous element, the most frequent hypothesis is that AFP-producing cells are Leydig-like cells. The hypothesis is that the presence of crystalloid present in the cytoplasm of Leydig-like cells at HE stain cannot be identified in immunohistochemical stainings because of technical dissolution of crystalloid [6]. Other authors suggest that AFP-producing cells are endodermal sinus differentiation tissue too early to be recognized histologically [12,19,20].
Some consider these cells as hepatoid whether or not a clear immunohistochemical staining for HepPar1 is seen [21,22]. In our case, AFP positive cells displayed immunostaining for CKAE1/AE3 and alpha-1-antitrypsin with no staining for Cytokeratin7 and HepPar1. Moreover, like the article of Ikota et al., the AFP-producing cells were negative for ovarian sex cord-stromal stainings (alpha-inhibin and calretinin). These results support that these cells are neither Sertoli nor Leydig-like cells. Thus, like Ikota et al., we suggest that AFP-producing cells can be derived from an abruptly differentiated tumor element into immature hepatocytes [23].
Talerman and Farley et al. suggest that AFP quantity would be associated to the importance of Leydig-like cell component and tumor size [24,25]. According to Tiltman et al., retiform pattern that is defined as irregular glandular zone resembling to rete testis seems to be associated with AFP production too [21].
Most authors insist that if AFP staining does not identify any cells, additional tissue sampling is mandatory to identify them [26].
In our complementary literature review, we found four new additional articles reporting five new cases since the last biggest review of Al-Hussaini et al. These cases are associated to heterologous elements and/or hepatocytes and mucinous epithelium with elevated AFP. AFP production is associated to Leydig cells in the case report of Singh et al. or to glandular mucosa cells of the colon in the others [8][9][10][11].
According to a large cohort study of Ovarian Sertoli-Leydig cell tumors by Young [2]. The optimal treatment algorithm is unknown given the rarity of SCSTs and clinical implications of different AFP producing cell origin are not known.
Furthermore, retiform pattern appears to be a misinterpretation problem and leads to describe it such as endodermal sinus tumor or serous adenocarcinomas [27].
Testing for DICER1 mutations should be performed in all patients with SLCTs because of management and therapeutic consequences. DICER1 mutations can be of germline or somatic type. In the case of germline mutations, called DICER1 syndrome, significant clinical relapse and morbidity occur in patients at young age [28].

Conclusion
In summary, we reported the case of a 15-year-old female with an unusual type of SLCT and highly elevated serum alpha-fetoprotein levels. AFP and alpha-1-antitrypsin stainings identified isolated AFP-producing cells.
An adequate sampling and microscopic examination are mandatory to identify AFP-producing cells in the cases of SLCT with AFP serum level elevation because of adjuvant therapy management.
These cells are reported to be of several origins such as intestinal-type mucinous epithelium, hepatocytes, Sertoli-Leydig cells, undifferentiated endodermal sinus differentiation tissue, retiform pattern, or abruptly differentiated tumor element into immature hepatocytes. In our case, we consider the AFP-producing cells to be immature hepatocytes.
This case contributes to the available knowledge on the biological, clinical, and histological diversity of SLCTs and specifically at this exceptional form with AFP-producing cells.

Data Availability
The data that support the findings of this case report are available from the corresponding author, Kacar Serife.

Conflicts of Interest
The authors declare that they have no conflict of interest regarding the publication of this article.