bladder adenocarcinoma

Types

 Intestinal type (or enteric type):

• Resembles colonic adenocarcinoma (Cancer 1991;67:2165)
• Neoplastic glands are lined by pleomorphic mucin producing pseudostratified columnar epithelium
• Central dirty necrosis is commonly seen

 Mucinous (colloid) type:

• Nests of neoplastic cells floating in abundant extravasated mucin
• Singly dispersed or groups of signet ring cells can be seen in the mucin pools
• Mucin usually deeply invades muscularis propria

 Signet ring cell type (diffuse poorly differentiated adenocarcinoma):

• Discohesive round cells with large intracellular mucin vacuoles displacing nuclei to the periphery without extracellular mucin
• Diffusely infiltrating stromal tissue

 Association with in situ component is an important clue to differentiate primary adenocarcinoma of the bladder from secondary adenocarcinoma involving the bladder

 Intestinal metaplasia or villous adenoma may be seen

IHC

 CK7 (variable)
 CK20 (variable)
 CEA
 EMA
 villin
 Variable CDX2 (Am J Surg Pathol 2003;27:303, Mod Pathol 2005;18:1217)
Membranous staining for beta-catenin

Differential diagnosis

 colonic metaplasia :

• may mimic well differentiated adenocarcinoma due to widespread involvement with dissecting mucin pools; however minimal atypia, no mitoses, no signet ring cells, usually non-infiltrative, minimal/no muscle invasion (Hum Pathol 1997;28:1152)

 florid cystitis glandularis :

• no nuclear anaplasia, rarely invades muscularis propria

 local extension of colonic cancer:

• no urothelial carcinoma in situ, positive nuclear staining for beta-catenin in 81%, CK20+ in 94%, CK7 negative in 100%, thrombomodulin negative in 100%, vs. bladder adenocarcinoma which has negative nuclear staining for beta-catenin in 100%, CK20+ in only 53%, CK7+ in 65%, thrombomodulin+ in 59% (Am J Surg Pathol 2001;25:1380, Am J Surg Pathol 1993;17:171)

 local extension of prostatic adenocarcinoma:

• most prostatic adenocarcinomas are PSA+ and PAP+, negative for p63, high molecular weight cytokeratin and thrombomodulin, but bladder adenocarcinomas are opposite

 metastatic disease : usually associated with known disseminated disease (Hum Pathol 1997;28:1152), submucosal centered, extensive vascular invasion
Mullerianosis

 urothelial carcinoma with glandular features: doesn’t differentiate towards colonic mucosa, usually minimal mucin and goblet cells, “glands” are surrounded by urothelial-type cells