Okay, here is some detective work.  This is an excellent site on interpreting Bladder Biopsies…

http://www.cap.org/apps/docs/annual_meeting/presentations/2004/monday/AP110_Urinary_Bladder_Biopsy_Interpretation_Part_3.pdf

[quote] Occasionally,carcinomas are associated with a pronounced chronic inflammatory cell infiltrate,
which partially or substantially obscures the underlying tumor cells[/quote]

c.[quote] Frankly invasive carcinoma
1. Variants containing or exhibiting
(a) Deceptively benign features
• Nested pattern (resembling von Brunn’s nests)
• Small tubular pattern
• Microcystic pattern
• Inverted pattern[/quote]

Do you ever watch that TV show "House"?  That Doctor is a genius at diagnosing, but he usually goes through some bad diagnoses till he gets to the truth.  Good show.

Regards,
Rosemary