Introduction/Background Proper diagnosis of abnormal ovarian masses determines the extent of surgical procedure and adjuvant chemo/radiation treatment. Occasionally, invasive, radiologic and laboratory tests are inconclusive and planning of upcoming steps in management requires individual approach. Detailed description of such cases in scientific literature could be beneficial for the management of similar occurrences.

Methodology 54 year old patient admitted to the onco-gynecology department with pain and unpleasant sensation in right hypogastric area. Contrast-enhanced CT scan revealed non-contrast-enhancing, nonhomogeneous cystic mass, 10.6 cm in diameter in place of right ovary. 2,7 cm and 2.3 cm masses were visualized in pararectal and presacral areas, embedded in retroperitoneal fat. Ovarian markers were within normal range. Primary colorectal origins were ruled out by colonoscopy. Based on pap test results, there was no suspicion of cervical cancer. Ovarian cancer seemed the most probable diagnosis.

Laparotomy was performed for diagnostic and curative purposes. During the procedure, gross image presented accumulation of 500 ml of ascitic fluid, pathologically changed ovaries and several pelvic/paraaortic lymph nodes, as well as palpable retroperitoneal masses located in presacral area, in close proximity to upper rectum and sigmoid colon.

Hysterectomy with bilateral salpingo-oophorectomy and sigmoid colon resection with colorectal anastomosis was completed. Frozen section examination reported serous ovarian cystadenofibroma. Morphologic structure of resected retroperitoneal masses was consistent with undifferentiated (squamous or transitional cell) carcinoma. Intraoperative cystoscopy revealed no lesions. Omentectomy and pelvic and paraaortic lymph node dissection was performed for preventive measures.

Results Definitive pathomorphological analysis confirmed the diagnosis of ovarian cystadenofibroma and signs of squamous cell carcinoma in tissues resected from retroperitoneum with lymphatic involvement and P16 positivity on immunohistochemical study. Primary site of cancer couldn’t be detected neither in genital nor head and neck areas.

Conclusion Diagnosis of squamous cell carcinoma changed the postoperative management, resulting in potentially increased survival rate.