Region of the ampulla of Vater
A carcinoma composed of malignant glandular cells and malignant squamous cells.
Adenosquamous carcinoma of the ampulla of Vater
This unusual neoplasm represents 1% of all ampullary carcinomas and is characterized by a variable combination of two malignant components, one glandular and the other squamous, like adenosquamous carcinomas seen in other anatomic sites
Song DE, Park JK, Hur B, Ro JY (2004)
. Although the proportion of each component varies, the adenocarcinoma usually predominates, is well- to moderately differentiated, and of pancreatobiliary phenotype. The squamous carcinoma component is focally keratinizing and by convention should represent at least 25% of the tumour. In contrast, any amount of glandular differentiation suffices to designate a predominantly squamous neoplasm as adenosquamous carcinoma. In some cases, clear cells line the glands and are mixed with the squamous elements. A micropapillary pattern can be seen rarely
Carcinoid tumor arising in a tailgut cyst of the anorectal junction with distant metastasis: a case report and review of the literature.
Arch Pathol Lab Med 128: 578-80
Khayyata S, Basturk O, Adsay NV (2005)
. Some adenosquamous carcinomas arise from preexisting adenomas
Invasive micropapillary carcinomas of the ampullo-pancreatobiliary region and their association with tumor-infiltrating neutrophils.
Mod Pathol 18: 1504-11
Bosman FT, Carneiro F, Hruban RH, Theise ND (Eds.)
WHO Classification of Tumours of the Digestive System.
International Agency for Research on Cancer: Lyon 2010