An unusual case of late recurrent adult granulosa cell tumor and mature teratoma arising within the same ovary, confirmed by NGS analysis

* Correspondence address:
Doc. MUDr. Kristýna Němejcová, Ph.D
Department of Pathology
First Faculty of Medicine, Charles University and General University Hospital in Prague
Studničkova 2, 12800 Prague 2, Czech Republic
tel.: +420224968632
e-mail: kristyna.nemejcova@vfn.cz

Ovarian sex cord-stromal tumors comprise a heterogeneous group of neoplasms characterized by variable biological behavior, classified into three categories according to the cellular origin; including pure stromal tumors, pure sex cord tumors, and mixed sex cord-stromal tumors (1). Adult granulosa cell tumor (AGCT) is the most prevalent malignant subtype within the sex cord-stromal tumor group, accounting for approximately 3% to 5% of all ovarian malignancies. A subset of ovarian sex cord-stromal tumors exhibits uncertain biological behavior, with AGCT in particular prone to late recurrences which significantly reduce the survival rate (2-3). Recent advancements in molecular biology have facilitated the resolution of challenging cases where morphological and immunohistochemical features overlap, for example in case of missense FOXL2 (c.402C>G, p.Cys134Trp) mutation which is mostly found in AGCT and a subset of Sertoli Leydig cell tumors (SLCT), as described in our recent publication (4-6). Mature teratomas are a type of germ cell tumor and represent one of the most common ovarian neoplasms. They are characterised by the presence of differentiated tissues derived from all three germ layers: ectoderm, mesoderm, and endoderm (1,7). Mature teratomas are benign tumors, in contrast to immature teratomas, which are malignant and are graded based on the amount of immature neuroectodermal tissue (1). However, malignant transformation of mature teratoma occurs in approximately 2% of cases with squamous cell carcinoma being the most common type of somatic malignancy arising in a mature teratoma (8). Various other somatic malignancies have been documented arising within teratomas, including rare cases of sex cord-stromal tumors, exclusively AGCT (7,9). Nevertheless, most of the existing literature describes AGCT and mature teratoma as independent synchronous neoplasms, in contrast to secondary somatic malignancies arising within a pre-existing mature teratoma (7). We present a unique case of a 71-year-old woman with, to our knowledge, the first documented instance of a recurrent AGCT arising concurrently with a mature ovarian teratoma, confirmed through both immunohistochemistry and molecular biological analysis.

CLINICAL HISTORY

The patient was a 71-year-old female with diffuse large B-cell lymphoma (DLBCL) in personal history, who underwent bilateral adnexectomy and hysterectomy in 2007 with an incidental finding of a mature cystic teratoma of the left ovary. In 2023 imaging revealed a sigmoid colon mass and multiple liver lesions suspicious for metastases, which were treated by resection of the sigmoid colon and a biopsy of the liver lesions, followed by subsequent chemotherapy. As of November 2024, the patient remains alive with active disease and is currently undergoing chemotherapy to manage the liver metastases.

MATERIALS AND METHODS

Immunohistochemical analysis

Immunohistochemical (IHC) analysis was performed using 4-μm-thick sections of formalin-fixed and paraffin-embedded (FFPE) tissue. The list of antibodies used, their clones, manufacturers, dilution, and staining instruments is summarized in Table 1.

Molecular analysis

Genomic DNA was isolated from FFPE tissue from the recurrent AGCT (estimated tumor purity was 95 % of tumor cells) and from the AGCT associated with a mature teratoma of the ovary (80 % of tumor cells) using the Quick-DNA/RNA FFPE Miniprep Kit (Zymo Research), according to the manufacturer’s protocol.

Sequence capture NGS analysis of the DNA was performed using the KAPA HyperPlus kit according to KAPA HyperCap Workflow v3.0 (Roche) and a panel of hybridization probes against multiple targets of cancer relevant genes (360 genes or gene parts; 951 kbp of coding regions; Roche). Unique Molecular Identifiers (UMIs) were incorporated during library preparation in the primary tumor (from 2007) to remove sequencing errors, unmasking low-frequency variants. The prepared sample libraries were pair-end sequenced by the NextSeq 500 instrument (Illumina) using NextSeq 500/550 High Output Kit v2.5 (Illumina). The biostatistical evaluation was performed using CLC Genomics Workbench software (CLC GW; Qiagen, Venlo, The Netherlands) and variants with mutation allele frequency (MAF) of at least 4 % were identified. Interpretation of the DNA variants was performed as described in a previous study (10). All variants were manually reviewed using the IGV software to eliminate potential sequencing artifacts or PCR duplicates and were analyzed and compared between both tumors. A variant with ≥ 1% MAF detected in the primary tumor was considered present if it was also detected in the recurrent tumor.

RESULTS

Morphological and immunohistochemical findings

The sigmoid colon mass measured 80x70x60 mm, presenting as a homogenous yellow mass with focal areas of necrosis, and was situated within the muscularis externa and subserosal layers of the colon. Histologically, the tumor exhibited features of AGCT with predominantly diffuse growth pattern, with areas of trabecular and alveolar structures and multiple necrotic areas. The tumor cells displayed eosinophilic cytoplasm and relatively uniform, larger vesicular nuclei with prominent nucleoli. In certain regions the tumor showed marked nuclear atypia, including the presence of monstrous nuclei and frequent mitotic figures. During the diagnostic evaluation of the sigmoid colon tumor, the left ovarian tumor diagnosed in 2007 as mature teratoma was re-examined, and the second reading showed focal areas of a tumor with AGCT features growing in a close proximity to the mature teratoma, which was made up of structures of a dermoid cyst, thyroid gland tissue, and mucinous epithelium. The biopsy of one of the liver lesions showed a tumor of the same morphology of AGCT as the mass in the sigmoid colon. Representative examples of the microscopic features (H&E staining) of the primary and recurrent tumors, along with the results of SF1 and p53 immunohistochemistry of the recurrent tumor are presented in Figure 1. The results of the immunohistochemical examination are provided in Table 1.

Table 1. List of the immunohistochemical antibodies used, including their clones, manufacturers, dilution, staining instruments, and a summary of the results in the primary and recurrent adult granulosa cell tumor.

MAF: mutation allele frequency; AGCT: adult granulosa cell tumor

Molecular findings

A total of five pathogenic or likely pathogenic mutations in FOXL2 (p.Cys134Trp), RB1 (p.Cys712Ter), TSC2 (c.2546-1G>C splice variant) and two mutations in TP53 gene (p.Arg273Cys and p.Leu257Arg ) were detected in the recurrent sex cord-stromal tumor. Only the FOXL2 mutation and one TP53 mutation (p.Leu257Arg) were also detected in the primary tumor with a low mutation allele frequency (MAF; 13% and 1%, respectively). Detailed list of the pathogenic or likely pathogenic variants is provided in Table 2.

Table 2. Detailed pathogenic or likely pathogenic variants detected in both tumors.

estimated tumor purity 80%  estimated tumor purity 95%