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WHO Classification of Tumours
Tubular adenoma, NOS
Gallbladder and extrahepatic biliary tract


Tubular adenoma, pyloric-gland type (pyloric- gland adenoma) is the most common variant of gallbladder adenoma. It is composed of lobules of closely packed pyloric-type glands, some of which may be cystically dilated, often covered by normal biliary epithelium. Squamoid morules characterized by nodular aggregates of cytologically bland spindle cells with eosinophilic cytoplasm but no keratinization are also seen
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Kushima R, Remmele W, Stolte M, Borchard F (1996)
Pyloric gland type adenoma of the gallbladder with squamoid spindle cell metaplasia.
Pathol Res Pract 192: 963-9; discussion 970-1

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Nishihara K, Yamaguchi K, Hashimoto H, Enjoji M (1991)
Tubular adenoma of the gallbladder with squamoid spindle cell metaplasia. Report of three cases with immunohistochemical study.
Acta Pathol Jpn 41: 41-5

. Paneth cells and neuroendocrine cells are often present. By definition, pyloric-gland adenomas have at least low-grade intraepithelial neoplasia. Larger adenomas may have high-grade intraepithelial neoplasia or may be associated with foci of invasive carcinoma. As they enlarge, some develop a pedicle and project into the lumen. Rarely, they extend into or arise from Rokitansky-Aschoff sinuses, a finding that should not be mistaken for invasive carcinoma
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Albores-Saavedra J, Vardaman CJ, Vuitch F (1993)
Non-neoplastic polypoid lesions and adenomas of the gallbladder.
Pathol Annu 28 Pt 1: 145-77

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Bosman FT, Carneiro F, Hruban RH, Theise ND (Eds.)
WHO Classification of Tumours of the Digestive System.
4th Edition
International Agency for Research on Cancer: Lyon 2010