[972] Pseudoangiosarcomatous (Acantholytic) Variant of Urothelial Carcinoma of the Urinary Bladder

Gladell P Paner, Roni Michele Cox, Michael Large, Aaron J Cohn, Neriman Gokden, Norm D Smith, Thomas Krausz, Jesse K McKenney, Gary D Steinberg. University of Chicago, Chicago, IL; University of Arkansas, Little Rock, AK; Standford University, Stanford, CA

Background: We present an unusual morphologic pattern of urothelial carcinoma of the bladder. Although rare instances of this morphology had been reported in other organ carcinomas, only one example in the bladder has been previously described in the literature.
Design: Six radical cystectomies obtained from the surgical pathology files of two institutions formed the basis of this study.
Results: Patients included 5 males and 1 female ranging from 47 to 78 years old (mean 63 years). Histologically, the tumor was characterized by florid vascular-like formations of invasive carcinoma cells. There were elongated jagged and larger nests of cells with abundant central acantholysis and dyscohesion. Complete cell loss imparted an appearance of interanastomosing network of vascular-like channels lined by residual plump hobnailing cells reminiscent of epithelioid angiosarcoma. In addition, dyscohesion or cracking in smaller elongated nests formed slit-like spaces and occasionally, intracytoplasmic vacuoles were also seen. When in the muscle, the tumor tended to infiltrate in between and wrapped around smaller muscle bundles. The acantholytic areas were often accompanied by abundant acute inflammatory cells. Other admixed morphologies included squamous (3/6, 20-40% of tumor), small cell neuroendocrine (1/6, 15% of tumor) and sarcomatoid (1/6, 50% of tumor) differentiations. Pseudoangiosarcomatous pattern was similarly seen in the squamous component. Immunohistochemical stains in 3 tumors for Fli-1, CD31 and CD34 were all negative. AJCC pT stages were as follows: pT3a (2), pT3b (2) and pT4a (2) and 2/6 had lymph nodal metastasis at time of surgery. 1 patient had concomitant Gleason score 9 and pT3 prostate adenocarcinoma. Follow-up available in 4 patients (mean 6.7 months) showed metastasis in 1 patient and 2 patients died at 2 months and 4 months follow-up.

Conclusions: We present an unusual morphologic pattern of bladder carcinoma with striking resemblance to a malignant vasoformative tumor. Knowledge of this pattern is important to avoid misdiagnosis particularly in smaller TURBT samples. It appears that this morphology is associated with higher tumor stage and suggests a poorer outcome.
Category: Genitourinary (including renal tumors)

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 154, Wednesday Afternoon


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