Immunohistochemical Expression of SATB2 and PAX8 in Differentiating Primary from Metastatic Ovarian Mucinous Neoplasms

Abstract Background Accurate stratification of an ovarian mucinous neoplasm as primary or secondary is always challenging. The ovary is a frequent metastatic site for primary gastrointestinal malignancies that shows overlapping histomorphological and immunohistochemical features with primary ovarian mucinous carcinomas. This study assessed the value of immunohistochemical expression of SATB2 and PAX8 in this diagnostic dilemma as single and combined panels. Methods Immunohistochemical staining for SATB2 and PAX8 was performed on 80 cases of mucinous ovarian neoplasms subdivided into 53 primary ovarian mucinous neoplasms (POMNs) and 27 secondary ovarian mucinous tumors of gastrointestinal (GI) origin (12 metastatic adenocarcinomas of colonic origin, 7 metastatic adenocarcinomas of appendiceal origin and 8 metastatic adenocarcinomas of gastric origin). Expression was correlated with different clinicopathologic parameters. Results PAX8 positive immunostaining was detected in 38/53 cases (71.69%) of POMNs with null positivity in the sub-group of secondary ovarian mucinous tumors of GI origin (0/27). On the other hand, SATB2 positive immunohistochemical staining was detected in 16/27 cases (59.26%) of the secondary ovarian mucinous tumors of GI origin. None of the studied POMNs showed any positive immunostaining for SATB2 (0/53). Conclusion A Profile of SATB2- /PAX8+ and SATB2+ / PAX8- can be used to differentiate POMCs from secondary ovarian mucinous tumors of GI origin, respectively, with a 100% specificity. This warrants the use of SATB2 and PAX8 in clinical practice for helping in the dilemma of diagnosing an ovarian mucinous neoplasm with higher precision. Moreover, PAX8 expression is associated with some clinico-pathologic parameters providing the basis for further studies for the possible usage of PAX8 as prognostic marker.