title: Primary endometrioid adenocarcinoma of the large intestine arising in colorectal endometriosis.
abstract: OBJECTIVE
  Three cases of endometrioid adenocarcinoma arising in colorectal endometriosis are described with discussion of their macroscopic and microscopic pathology and diagnosis, using immunohistochemistry.
  
  
  RESULTS
  Three middle-aged women presented with symptoms and signs of colorectal mass effect. Two had a preceding history of gynaecological endometriosis and all three had either been on hormone replacement therapy or had functioning ovaries prior to presentation with colorectal disease. Each underwent resection of tumours of the distal large intestine. The definitive diagnosis was dependent on histological examination and immunohistochemistry, which was used to demonstrate an origin in endometriotic tissue.
  
  
  CONCLUSIONS
  Endometrioid adenocarcinoma is a rare complication of colorectal endometriosis, this report contributing to a total of 25 cases in the literature. Definitive diagnosis, aided by immunohistochemical studies, is important to enable the identification of the optimal management for this uncommon condition.
authors.affiliation: Department of Histopathology, Gloucestershire Royal Hospital, Gloucester, UK.
authors.forename: V C
authors.initials: VC
authors.lastname: Petersen
authors.forename: J C E
authors.initials: JC
authors.lastname: Underwood
authors.forename: M
authors.initials: M
authors.lastname: Wells
authors.forename: N A
authors.initials: NA
authors.lastname: Shepherd
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D018269:Carcinoma, Endometrioid / Q000209:etiology / Q000378:metabolism / Q000556:secondary*; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology; D015179:Colorectal Neoplasms / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D004715:Endometriosis / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged
chemical_list: D014408:Biomarkers, Tumor