Metastatic colorectal carcinoma mimicking primary ovarian carcinoma presenting as ‘giant’ ovarian tumors in an individual with probable Lynch syndrome: a case report

Ovarian metastases occur in 3 to 8% of women with primary colon cancer. In the setting of a pre-existing colorectal carcinoma this would constitute a hereditary non-polyposis colorectal cancer, Lynch 2 syndrome, accounting for 5 to 10% of colon cancer cases. We unveil a case of ‘giant’ ovarian tumors mimicking primary ovarian cancer; ostensibly the first reported in East Africa.

A 58-year-old African woman was diagnosed with colorectal adenocarcinoma in June 2009. She had a right hemicolectomy with the tumor staged as regional cancer, following histopathological examination. Chemotherapy was administered both adjuvantly and 1 year later for what was thought to be a recurrence of tumor. Despite this, her general condition deteriorated. Following re-evaluation and an exploratory laparotomy she was found to have bilateral ‘giant’ ovarian tumors, with peritoneal seedlings and subcutaneous metastases (colonic in origin). A bilateral salpingo-oophorectomy was done, accompanied by histopathological analysis with institution of chemotherapy for ovarian cancer. Following immunohistochemistry tests and microsatellite instability analysis it was found that the ovarian tumors were secondaries from the colon. She was also identified as a Lynch syndrome case or a case of sporadic microsatellite instability, although with no suggestive family cancer history. The treatment regimen was changed to suit metastatic disease.

The case presents a diagnostic and thus treatment conundrum. Two primary tumors (suspected Lynch syndrome) had been perceived yet there is actually only metastatic colorectal cancer. We also have a rare and unusual metastatic presentation: ‘giant’ bilateral ovarian tumors and subcutaneous nodules, concurrently. Further still, she is a case of probable Lynch syndrome, requiring genetic analysis for definitive classification and surveillance for hereditary non-polyposis colorectal cancer-associated cancers.

Important inferences are drawn. Firstly, ‘giant’ ovarian tumors diagnosed as primary ovarian cancer may actually be colonic secondaries. Secondly, immunohistochemistry and microsatellite instability analysis tests ought to be part of the diagnostic package in colon cancer management, particularly for identifying tumor origin and the Lynch syndrome (a condition which has had little attention in resource-limited countries). Thirdly, multidisciplinary team collaboration is emphasized in colorectal cancer management.