title: Composite adenocarcinoma and large cell neuroendocrine carcinoma of the rectum.
abstract: Composite glandular-endocrine tumors of the gastrointestinal tract are rare neoplasms. Even more uncommon are the so-called amphicrine tumors, lesions in which dual epithelial and endocrine differentiation occurs in the same cell. We describe a patient who complained of rectal pain and bleeding with a mixed or composite adenocarcinoma and neuroendocrine carcinoma of the rectum. Histological examination revealed a distinct adenocarcinoma of conventional type with glandular structures admixed intimately with a neuroendocrine carcinoma. The latter component was deeply infiltrative, while the adenocarcinoma occupied the more superficial aspect of the tumor. What was interesting was the immunophenotype of the lesion: cytokeratin (CK) 20 expression was very focal in the adenocarcinoma component and negative in the neuroendocrine carcinoma, while CK 7 was expressed strongly in the adenocarcinoma and only focally in the neuroendocrine component. This cytokeratin profile suggests a possible origin from the anal transitional zone.
authors.affiliation: Department of Pathology, University Health Network, Princess Margaret Hospital, 610 University Avenue, Fourth Floor, Suite 302, Room 312, Toronto, ON, M5G 2M9, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Makino
authors.forename: S
authors.initials: S
authors.lastname: Serra
authors.forename: R
authors.initials: R
authors.lastname: Chetty
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D000369:Aged, 80 and over; D018287:Carcinoma, Large Cell / Q000378:metabolism / Q000473:pathology*; D018278:Carcinoma, Neuroendocrine / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D009378:Neoplasms, Multiple Primary / Q000378:metabolism / Q000473:pathology*; D012004:Rectal Neoplasms / Q000378:metabolism / Q000473:pathology*