A Rare Histopathological Diagnosis: Endometrioid Adenocarcinoma Localized in the Rectum: a Case Report

Abstract

Endometriosis-associated intestinal tumors represent malignant transformation of gastrointestinal endometriosis. Clinical features are similar to colon tumor with abdominal or pelvic pain, dyschezia, or bloody stools. Intestinal occlusion or perforation has also been described as a first presentation. The diagnosis is often postoperative, and it is based on specific immunohistochemical patterns (CK7+/CK20−). We present a rare case of a woman with a malignant transformation of an endometriotic lesion of the sigmoid colon, who underwent emergency surgery for intestinal occlusion. She underwent an exploratory laparotomy and Hartmann resection. The immunophenotypic analysis of the specimens revealed the following pattern: CK20−, CK7+, compatible with the diagnosis of endometrioid adenocarcinoma. Endometrioid carcinoma is a rare tumor, difficult to diagnose preoperatively because of similar symptoms of sigmoid carcinoma. A high index of suspicion in conjunction with careful histological and immunohistochemical examination (CK7, CK20, CDX2, CD10, ER, and PR) is important for establishing a correct diagnosis.