Immunohistochemistry profile of the mucinous lesions of appendiceal and ovarian origin

Abstract

Introduction: Pseudomyxoma peritonei (PMP) is a rare clinical entity, characterized by a significant amount of mucinous ascites associated by peritoneal mucinous implants. The most frequent localization of primary lesion are the appendix and ovaries (epithelial mucinous lesions with varying histopathological architecture), although other primary sites of origin were described: gallbladder, stomach, pancreas, colon, uterus, fallopian tubes, urinary bladder, breast and lungs. There are still ongoing discussions in the literature about PMP, especially regarding the origins, histopathology and adequate treatment. The biological potential of the lesions depends on several factors which may be determined at the morphological examination. The primary aim is to identify the primary lesion site. In majority of PMP cases the primary lesion is originating from appendix. In some cases, though, there may be metastases to the ovaries, which need to be differentiated from primary mucinous ovarian lesions, especially in condition of grossly normal appendix. Taking in consideration all mentioned above, epithelium from different sites manifest different immunohistochemical expressions and this may help to identify the primary lesion site. Ovary epithelium and majority of tumors originating from the ovary manifest positive expression for cytokeratin 7 (CK 7) and are negative for cytokeratin 20 (CK 20), while appendiceal epithelium and tumors originating from appendix and colon are positive for CK 20 and negative for CK 7. Another specific immunohistochemical marker for colorectal and appendiceal origin tumors is the carcinoembrionic antigen (CEA). Materials and methods: Current paper included two cases of ovarian mucinous cystadenoma, two cases of PMP of appendiceal origin (mucinous cystadenocarcinom a) and one case of appendiceal mucinous cystadenocarcinoma. An immunohistochemical profile including CK 7, CK 20 and CEA for all the specimens was perfonned. Results: For cases of PMP of appendiceal origin (n=2) and appendiceal mucinous cystadenocarcinoma (n=l) a positive expression of CK 20 and CEA was obtained, manifested by moderate and/or intense reaction in cytoplasm and membrane of majority of tumor cells (C++/+++; M++/+++). Reaction for CK 7 was negative. For cases of ovarian mucinous cystadenoma (n=2) a positive expression of CK 7 was obtained, manifested by intense reaction in cytoplasm and membrane of the tall prismatic epithelium (C+++; M+++). Reaction for CK 20 and CEA was negative. Conclusion: Results obtained within the current study showed a difference of the immunohistochemical profile of the mucinous lesions of appendiceal and ovarian origin, thus confirming the available data. These findings prove that the immunohistochemical profiling may help to identify the origin of the primary lesion and this have an impact on the subsequent management of these patients.