Bladder
Urothelial carcinoma - invasive
Nested variant

Author: Rugvedita Parakh, M.D. (see Authors page)

Revised: 7 November 2016, last major update December 2014

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Nested variant urothelial carcinoma
Cite this page: Nested variant. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/bladderurothelialnested.html. Accessed December 6th, 2016.
Definition / General
  • Rare tumor of irregular and confluent small nests and abortive tubules composed of urothelial cells infiltrating the lamina propria or muscularis propria, usually without surface involvement
  • First described in 1989 (Am J Surg Pathol 1989;13:374)
Epidemiology
  • Usually men > 60 years, similar to classic urothelial carcinoma
Clinical Features
  • Either rare or underreported; estimated incidence is less than 0.3% of invasive bladder tumors
  • Aggressive behavior despite bland cytologic features (Mod Pathol 2003;16:1289)
  • Similar clinical outcome if pure or mixed with usual urothelial carcinoma (Hum Pathol 2010;41:163)
  • Often advanced stage at presentation
  • Tumor often at ureteral orifices
  • Neoplasm resembles proliferation of Brunn's nests (Mod Pathol 1992;5:240); may be misinterpreted as benign (Am J Surg Pathol 1996;20:1448)
Case Reports
Treatment
  • Radical surgical resection
Gross Description
  • Often no clearly defined tumor
Micro Description
  • Irregular and confluent small nests and abortive tubules composed of urothelial cells infiltrating the lamina propria or muscularis propria, usually without surface involvement (Arch Pathol Lab Med 2007;131:1725)
  • Tumor cells have only mild atypia (mild pleomorphism, slightly increased N / C ratios, occasional prominent nucleoli, rare mitotic figures) and resemble cystitis glandularis et cystica
  • Deep tumor-stroma interface is jagged and infiltrative
  • Often more atypia and focal anaplasia with increasing depth of invasion
  • Typical urothelial carcinoma is often present (Mod Pathol 1996;9:989)
  • Retraction artifact may be seen
  • By definition, these tumors cannot be high grade or have overlying surface carcinoma in situ
Micro Images
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AFIP 2-30: The tumor usually presents as multiple, deceptively benign appearing nests in the lamina propria



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Histological appearance of the urinary bladder

Cytology Description
  • Subtle features are not diagnostic by themselves; include medium sized round / polygonal cells with abundant, dense, slightly granular basophilic cytoplasm and well defined cell borders; irregular nuclear contours, increased N / C ratio, coarse chromatin, occasional prominent nucleoli (Cancer 2003;99:23)
Positive Stains
Negative Stains
Differential Diagnosis