Immunohistochemical Characterization of 120 Testicular Sex Cord-Stromal Tumors With an Emphasis on the Diagnostic Utility of SOX9, FOXL2, and SF-1.

Sex cord-stromal tumors (SCSTs) account for the second most common category of testicular neoplasms and include several entities that may show overlapping morphologies and present diagnostic challenges. We analyzed a cohort of 120 testicular SCSTs and investigated the diagnostic utility of SRY-box transcription factor 9 (SOX9), forkhead box protein L2 (FOXL2), and steroidogenic factor 1 (SF-1) immunohistochemical stains. The results were compared with the more commonly used SCST markers, inhibin α, calretinin, and Wilms' tumor 1 (WT1). SF-1 was overall the most sensitive stain (91%), followed by inhibin α (70%), calretinin (52%), FOXL2 (50%), SOX9 (47%), and WT1 (37%), but sensitivities varied by tumor type. SOX9 and calretinin were more commonly positive in sex cord elements versus stromal elements (62% vs. 27% and 47% vs. 9%, respectively), whereas FOXL2 was more commonly positive in stromal elements versus sex cord elements (100% vs. 55%) when excluding Leydig cell tumors from the stromal category. Although no individual stain was diagnostically specific, some immunophenotypic patterns were noted that may help in the subclassification of SCSTs. We conclude that SOX9, FOXL2, and SF-1 are useful immunohistochemical stains for confirming sex cord-stromal differentiation in testicular tumors and provide increased sensitivity as well as additional diagnostic information, especially when combined with the more commonly used inhibin α, calretinin, and WT1 immunostains. Although morphology is paramount for subclassification of SCSTs, knowledge of certain immunohistochemical patterns may be helpful for diagnostically challenging cases.

The role of FOXL2, SOX9, and ß-catenin expression and DICER1 mutation in differentiating sex cord tumor with annular tubules from other sex cord tumors of the ovary.

Sex cord tumor with annular tubules (SCTAT) is a highly rare type of ovarian sex cord-stromal tumor (SCST), the diagnosis of which remains to be challenging. The aim of this study was to scrutinize the utility of three immunohistochemical markers including Forkhead box protein 2 (FOXL2), SOX9, and ß-catenin and DICER1 mutation status in distinguishing SCTATs from other ovarian SCSTs. Nine cases of SCTAT, 10 Sertoli-Leydig cell tumor (SCLT), 10 adult-type granulosa cell tumor (AGCT), and 8 juvenile-type granulosa cell tumor (JGCT) were included in the study. SCTATs were characterized by diffuse and strong expression of SOX9, focal and weak expression of FOXL2, and the absence of DICER1 mutation. However, AGCTs and JGCTs displayed strong and diffuse expression of FOXL2, focal/no immunoreaction for SOX9. SLCTs generally showed moderate intensity of FOXL2 and SOX9 expression. Nuclear ß-catenin expression was observed in none of SLCT, 1/9 of SCTAT, 6/8 JGCT, and 4/10 AGCT cases, respectively. DICER1 hotspot mutation was detected in only 3 cases of SLCT and 2 cases of JGCT. We conclude that in addition to strong and diffuse SOX9 expression, weak/absent expression of FOXL2 is suggestive for the diagnosis of SCTAT. Hence, we suggest that inclusion of these two markers, SOX-9 and FOXL2, to the immunohistochemical panel helps in differentiation of SCTAT from other SCSTs in addition to morphologic findings. We also conclude that SCTATs of the ovary do not harbor DICER1 hotspot mutation.

Correlation of FOXL2 with Inhibin and Calretinin in the Diagnosis of Ovarian Sex Cord Stromal Tumors.

OBJECTIVE: Alpha-inhibin and calretinin have been traditionally used as immunomarkers for sex cord stromal tumors. However, the variation in their immunoreactivity and their lack of specificity for sex cord stromal tumor makes the search for a more sensitive and specific immunohistochemical marker essential in routine diagnosis of sex cord stromal tumor. This study was conducted to correlate the diagnostic utility of FOXL2 with inhibin and calretinin in the diagnosis of sex cord stromal tumors of ovary. MATERIAL AND METHOD: The study was conducted in the department of pathology. 31 cases of sex cord tumors received in past eight years (2002-2010) were included in this study. Immunostaining for inhibin, calretinin and FOXL2 was performed and compared on the basis of staining intensity and percentage positivity on all the cases. RESULTS: Calretinin was found to be positive in 29/31 sex cord stromal tumors with variable intensities and was negative in two cases of sex cord stromal tumors, inhibin was positive in 28/31 and only three cases had no cytoplasmic staining. All the 31 cases included in this study were positive for FOXL2 with variable staining intensities and percentage positivity. Ten cases of each surface epithelial and germ cell tumors were also negatively stained with FOXL2. CONCLUSION: In contrast to inhibin and calretinin, FOXL2 had a sensitivity and specificity of 100% for all the cases of sex cord stromal tumors included in this study.