Mismatch Repair Deficiency in Adult Granulosa Cell Tumors: an Immunohistochemistry-based Preliminary Study

Objective: Adult granulosa cell tumors (AGCTs) are rare ovarian malignant neoplasms; their etiopathogenetic mechanisms remain largely unelucidated. Lately, defects in mismatch repair (MMR) have been implicated in the pathogenesis of AGCTs. Demonstration of MMR deficiency in these tumors can help identify patients potentially eligible for immune checkpoint inhibition therapy. The present study was done to explore the role of MMR deficiency in the etiopathogenesis of AGCTs. Methods: This was a retrospective study conducted on histopathologically confirmed AGCT cases. MMR protein expression was evaluated by immunohistochemistry (IHC) on tissue microarrays using an antibody panel of MSH2, MSH6, MLH1, and PMS2. Results: Of a total of 40 ovarian AGCTs evaluated for MMR deficiency, none demonstrated loss of expression of any of the 4 MMR proteins. Conclusions: The results of our preliminary study show that there is no association between MMR deficiency with AGCT. Nevertheless, larger multicenter studies are needed to confirm or refute this observation.