en Clinical Medicine Clinical Medicine <p style="text-align: justify;"><span style="font-size:16px;"><span style="font-family:Times New Roman;">Synchronized evidence of bilateral ovarian masses with an asymptomatic&nbsp; incidental appendiceal solitary mass is an unusual&nbsp; event during&nbsp; operation.&nbsp; The main differential diagnosis in this status&nbsp; is metastatic mucinous adenocarcinoma of ovary to appendix&nbsp; versus&nbsp; metastatic mucinous neoplasm of appendix&nbsp; in both side ovaries. Herein, i present a &nbsp;metastatic bilateral ovarian high grade serous carcinoma to the appendix as &nbsp;a diagnosis pitfall. A 43-year-old woman, with menstrual irregularity was referred. Imaging studies &nbsp;showed bilateral ovarian masses. She underwent total abdominal hysterectomy, bilateral salpingo oophorectomy , omentectomy,&nbsp; pelvic lymph nodes dissection and appendectomy.&nbsp; Final diagnosis, according to histopathological and immunohistochemical findings was metastatic bilateral ovarian high grade serous carcinoma of the appendix. These tumor markers may be useful for final diagnosis because tumoral tissue expression of them is not 100%. Therefore usage of several of them in correlation with histopathology findings, definitely helpful.</span></span></p> Metastasis, Ovary, Appendix, Cystadenocarcinoma, Serous. 468 470 http://journal.zums.ac.ir/browse.php?a_code=A-10-1771-4&slc_lang=en&sid=1 Fatemeh Samiee-Rad fsamieerad@gmail.com 5200319475328460073643 5200319475328460073643 Yes Dept. of Pathobiology, Clinical Research Development Unit, Kosar Hospital, Qazvin University of Medical Sciences, Qazvin, Iran