Bladder
Urothelial carcinoma-invasive
Endophytic growth pattern

Author: Monika Roychowdhury, M.D. (see Authors page)

Revised: 18 July 2016, last major update December 2014

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

PubMed Search: Endophytic growth pattern [title]
Definition / General
  • Endophytic growth pattern can be associated with papilloma, urothelial neoplasm of low malignant potential, low / high grade tumors that are noninvasive or invasive; this topic discusses invasive tumors
  • Anastomosing cords and columns of urothelium resembling inverted papilloma or broad pushing bulbous invaginations into lamina propria (broad front pattern), but with definitive evidence of invasion
  • Not a WHO diagnosis
Epidemiology
  • Mean age 68 years
  • 75% male
Clinical Features
  • Pattern present in 11% of urothelial carcinomas
  • Associated with high grade and high stage tumors, and possibly poorer prognosis (Urol Oncol 2012;30:49)
Micro Description
  • Anastomosing cords and columns of urothelium resembling inverted papilloma or broad pushing bulbous invaginations into lamina propria (broad front pattern)
  • The trabecuale are wider and more irregular than those of inverted papilloma
  • Invasive if there is irregularity of broad front of bulbous invaginations, retraction artifact, desmoplasia or other features of destructive invasion
  • Usually exophytic papillary urothelial carcinoma is also present
  • Substantial nuclear pleomorphism, readily apparent mitotic figures and architectural abnormalities
  • At least 25% of tumor should have an inverted component to be considered as inverted urothelial carcinoma (BJU Int 2011;107:532)
  • Findings suggestive of invasion – irregularly shaped nests with disruption or absence of the basement membrane, desmoplasia or fibrotic stromal response (note that microinvasion usually does not elicit a stromal response, which makes its identification more difficult)
  • Pattern is associated with invasion in 50% of papillary urothelial carcinomas (Am J Surg Pathol 1997;21:1057)
  • Urothelial carcinoma in situ, if present in the surface urothelium, provides support for a diagnosis of inverted urothelial carcinoma
Differential Diagnosis