Presentation
Colonoscopy for chronic anemia which showed a huge rectal mass. CT staging performed.
Patient Data
Findings: Enhanced CT of thorax and abdomen shows a huge, space-occupying pelvic mass with vivid enhancement, measuring approximately 9 x 7 x 9 cm in greatest dimension. The mass is relatively well-defined and invades the adjacent rectum. The uterus is displaced ventrally, the mass abuts but does not seem to infiltrate the uterus. There seems to be involvement of the right ovary's lower pole.The left ovarian veins are engorged. Local lymph nodes are not enlarged.
No signs of metastasis in distant lymph nodes, liver, lung or bone. No other pathological findings. Uncomplicated bilateral renal cysts.
Conclusion: Huge, pelvic, enhancing mass with rectal infiltration. No distant metastasis.
Findings are compatible with a primary ovarian/uterine cancer. A mesenchymal/sarcomatous origin was also taken into consideration.
A primary discontinuity resection of the rectum was performed as well as a total mesorectal excision, pelvic peritonectomy, hysterectomy and adnexectomy.
Pathology/Histology: Surprisingly, the pathologic specimen revealed a primary peritoneal serous carcinoma with infiltration of all layers of the rectum and a metastasis in the right ovary. No lymph node metastasis or peritoneal carcinomatosis.
Case Discussion
The histologic result caught everyone pretty much by surprise since a primary peritoneal carcinoma is a rare tumor entity, with a very low incidence of only about 6 cases per million per year 1, making it more than 20 times less frequent than a primary ovarian cancer, with which it shares a lot of histological similarities. In fact, some articles suggest that as many as 7-15 % of diagnosed ovarian cancers will actually turn out to be a primary peritoneal cancer 2.
The distinct image appearance in this particular case had everybody fooled, since this tumor does not have any of the features one would normally expect in primary peritoneal neoplasm - namely involvement of the peritoneum, lack of ascites and peritoneal masses. Besides, this tumor did not demonstrate an elevated CA-125, typical for ovarian cancer, making this an even rarer type of tumor. CEA, CA 19-9 and CA 15-3 were also negative.
The patient is currently undergoing chemotherapy, followed by a surgical re-exploration and HIPEC-therapy (hyperthermic intraperitoneal chemotherapy).