Delayed metastatic endometrial carcinoma mimicking primary colon adenocarcinoma: A surprise histopathological finding

Colorectal cancer is the third most common malignancy worldwide, with an increasing incidence. Colonic metastasis is a rare occurrence; thus, misdiagnosis is common. Immunohistochemistry facilitates accurate diagnosis and subsequent management.

Most cancers in the colon are primary colorectal cancers, however metastasis from another primary is possible, albeit rare. Endometrial cancer metastasis to the colon is a rare occurrence and is only described in a handful of cases. We describe a rare case of metastatic endometrial cancer in the colon presenting 5 years post radical hysterectomy and adjuvant radiotherapy in a 62-year-old female. She presented with a 1-week history of right upper quadrant pain, with no other associated symptoms. She was presumed to have a primary colorectal cancer based on her colonoscopy and CT findings; later proven otherwise by immunohistochemistry (IHC). Endometrial cancer metastasis to the colon is rare, thus misdiagnosis can easily occur. Currently, there are 6 similar cases reported in the literature, all occurring in the absence of colorectal endometriosis. This case illustrates the relative importance of considering colon as a potential site for metastasis of endometrial cancer and the utility of IHC in aiding diagnosis and guiding further management.