[933] Pseudoangiosarcomatous Variant of Urothelial Carcinoma of the Urinary Bladder

Vadim Khachaturov, Juan Hernandez-Prera, Pamela D Unger, Guang-Qian Xiao. Mount Sinai School of Medicine, New York, NY

Background: The pseudoangiosarcomatous (PAS) variant of urothelial carcinoma (UC) is extremely rare with only one published series to date, containing two cases. PAS variant is characterized by slit-like spaces resembling vascular channels, lined by a single layer of attenuated or epithelioid neoplastic cells which may be loosely cohesive. The aim of this study was to investigate the PAS variant, its relation to accompanying UC and its immunohistochemical (IHC) profile.
Design: Five cases over a two year period were obtained from our archives: 3 radical cystoprostatectomies, 1 nephroureterectomy and 1 transurethral bladder resection. H&E slides were evaluated for associated UC histologies. The following IHC stains were performed Ki-67, K903, CK 20, CK 7, CD31, p63, VEGF and Vimentin.
Results: Patients consisted of 5 males ranging in age from 66 to 90 years (mean 78 years). The percentage of PAS variant from each case ranged from 5% to 25%. All cases were associated with high grade UC: conventional (3), sarcomatoid (1), and conventional with focal squamous and glandular features (1). Overall the IHC profile of PAS variant versus associated UC showed similar IHC reactivities (Table 1). Of note the Ki-67 stained the PAS variant at lower percent as compared to the other accompanying urothelial morphologies (18% vs 66%).

Table 1. IHC Profile of PAS Variant and HGUC
IHCCase 1 PAS/SarcomatoidCase 2 PAS/HGUC SGCase 3 PAS/HGUCCase 4 PAS/HGUCCase 5 PAS/HGUC
Ki-67+15%/+80%+20%/+70%+<5%/+30%+20%/+60%+30%/+90%
K903+/++/++ weak/ + weak+ focal/ + focal+/+
CK 20-/--/--/+ weak-/--/-
CK 7+ weak focal/ + weak focal+/++/++/++/+
CD 31-/--/--/--/--/-
p63+/+-/--/--/-+/+
VEGF+/++/++/++ focal/ + focal-/-
Vimentin+/+-/--/--/-+/+
PAS = Pseudoangiosarcomatous, HGUC = High Grade Urothelial Carcinoma Conventional, SG = Squamous and Glandular Features


Conclusions: PAS variant of UC is rare and only seen in association with high grade UC. The majority of the IHC stains showed a high concordance between the PAS variant of UC as compared to accompanying conventional, sarcomatoid, squamous and glandular variants of UC. The proliferation index (Ki-67 stain) showed a substantial difference between the two groups. This may indicate that the PAS variant is a less aggressive tumor present within these high grade malignancies. Additional cases will need to be examined to support these findings.
Category: Genitourinary (including renal tumors)

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 145, Wednesday Morning

 

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