An extremely Rare Case of Primary Peritoneal Mucinous Cystadenocarcinoma

Abstract Introduction/Objective Primary peritoneal mucinous adenocarcinoma is an extremely rare entity with no well- established treatment protocol. It occurs more commonly in females as compared to males which supports its less understood pathogenesis of arising from heterotopic ovarian tissue or mucinous metaplasia of mesothelial cells. Methods/Case Report We present a case of a 31-year-old female who presented with right flank pain after a fall. On imaging studies, a cyst measuring 11.4 x 9.6 x 8.8 cm with an enhancing mural nodule was identified in abdomen (Figure 1). Patient underwent exploratory laparotomy. We received 402.1 grams, 12.5 x 10.0 x 8.0 cm cystic mass. Cut surface showed an unilocular cyst filled with seromucinous fluid and 4.0 x 2.5 x 1.7 cm friable excrescences. Histologic examination showed an adenocarcinoma arising from background mucinous cystadenoma. The tumor cells were positive for AE1/AE3, CK7, CK20, villin (focal), PAX8 (focal), p53 (wild-type) and negative for WT-1, AMACR, CDX-2, TTF-1, GATA-3, inhibin and calretinin. ER and PR immunostains were positive in the ovarian-type stroma in the background mucinous cystadenoma. As the radiology work-up was negative for any other tumor in the pelvis or other sites, the diagnosis of primary peritoneal cystadenocarcinoma was rendered. Molecular analysis showed presence of KRAS and TP53 mutations. Patient is doing well at 6 months follow-up without any recurrence. Results (if a Case Study enter NA) NA Conclusion This case is an extremely rare case of primary peritoneal mucinous cystadenocarcinoma and thus requires consideration that it should be included in the differential diagnosis of peritoneal tumors.