Endometriosis is a common disorder, while malignant transformation of endometriosis in the colon is rare. The main clinical manifestations include pelvic masses, abdominal or pelvic pain, vaginal bleeding, rectal bleeding, and intestinal obstruction. In early patients with endometriosis-related colon cancer, the most common involvement on imaging is the serosa or subserosa layer, with no mucosal lesions or minor lesions; while in advanced cases, it resembles primary colon cancer.This paper collected 2 cases of endometrioid carcinoma associated with rectal (extrinsic gonadal) endometriosis to investigate its clinicopathological features and molecular changes, and to review the relevant literature to improve the understanding of diagnostic physicians so as to avoid misdiagnosis.

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