A molecular and immunohistochemical study of 37 cases of ovarian Sertoli-Leydig cell tumor

Abstract

This study provides an analysis of 37 ovarian Sertoli-Leydig cell tumors (SLCT), focusing on their morphological, immunohistochemical, and molecular features. The cohort was comprised of 9 well-differentiated, 25 moderately differentiated, and 3 poorly differentiated tumors. The immunohistochemical analysis was performed with 28 markers, including diagnostic markers and markers with possible predictive significance. The results showed high expression of sex cord markers (FOXL2, SF1, inhibin A, CD99, calretinin, ER, PR, AR), and variable expression of other markers such as CKAE1/3 (83%), CAIX (14%), and MUC4 (1%). Loss of PTEN expression was present in 14% of cases, and CTLA4 expression was seen in 43% of cases. All tumors were MMR proficient and HER2 and PD-L1 negative. The molecular analysis showed DICER1 mutations in 54.5% of cases, and a FOXL2 mutation in 6% of tumors. In addition, we detected 2 cases with TERT promoter mutation. RNA NGS sequencing identified significant differences in mRNA expression between DICER1^MUT and DICER1^WT tumors. The DICER1^WT tumors showed increased expression of PRKCA, HNF1A, LDLR, and MAP2K5. On the contrary, the DICER1^MUT cases showed increased expression of CDK6, NOTCH2, and FGFR2. The results of our study show that SLCTs exhibit distinct molecular features based on their degree of differentiation. We have confirmed that DICER1 mutations are characteristic of moderately and poorly differentiated SLCTs, while well-differentiated SLCTs may represent a distinct entity. DICER1^MUT and DICER1^WT tumors showed different mRNA expression profiles. The FOXL2 mutation is less common in these tumors and is mutually exclusive with the DICER1 mutation.

Keywords: DICER1; Immunohistochemistry; MRNA expression; Ovarian tumors; Sertoli–Leydig cell tumor; Sex cord-stromal tumor.

Fig. 1

A CTLA4 expression (200 ×), B MUC4 expression (200 ×), C loss of PTEN expression (200 ×), and D loss of PTEN expression (400 ×)

Fig. 2

Clinicopathological and molecular findings of Sertoli–Leydig cell tumors. Each column represents a single case. The figure displays only the markers with variable expression (immunohistochemical findings); markers with lack of expression in all cases (such as GATA3, SATB2, napsin A, TTF1, HER2, PD-L1), ARID1A, MMR proteins and MUC4 (only 1 positive case) are not included. Only genes that were mutated in at least two cases are shown

Fig. 3

Significantly different mRNA expression between the DICER1^MUT and DICER^WT Sertoli–Leydig cell tumors. The transcripts per million (TMP) values of mRNA were normalized to the TPM of the housekeeping gene HPRT1. The listed p-values were adjusted using the Bonferroni correction. A A heat map displaying normalized TPM values in the groups DICER1^MUT and DICER1^WT (more intense red indicating higher mRNA levels and green indicating lower levels). B Distribution of mRNAs significantly decreased in the DICER1^WT group (normalized TPM values). C Distribution of mRNAs significantly increased in the DICER1.^WT group (normalized TPM values)