Contributed by Xin Li, MD and Katrina Han, MD
Contributed by Xin Li, MD and Katrina Han, MD
CLINICAL HISTORY
A 58 year old woman with a history of chronic diarrhea, post-menopausal uterine bleeding, and depression underwent a routine colonoscopy for colon cancer screening which demonstrated a large, nearly obstructing mass extending from the proximal rectum into the distal sigmoid colon. The colonoscopy examination shows a large mass partially occluding lumen of rectosigmoid colon (Fig. 1). The colonoscope could be traversed proximally and the remainder of the examination was normal.
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GROSS EXAMINATION
A 13.0 x 7.0 x 4.0 cm tan-brown polypoid multinodular lesion is located on the mucosal surface of the colon. The cut surface of the lesion is tan-pink and slightly gelatinous with focal cystic areas (Fig. 2).
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MICROSCOPIC EXAMINATION
Histological sections demonstrate that cystically dilated glands scatter beneath the colonic mucosa and show focal crowding. High power view reveals benign-appearing endometriotic glands and stroma, without atypia. Some glands show mucinous metaplasia (Fig. 3).
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IMMUNOHISTOPATHOLOGY
The glands are positive for CK7, ER, PAX8 and Vimentin; negative for CK20 and monoclonal CEA (Fig. 4).
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