[916] Papillary Urothelial Neoplasm of Low Malignant Potential and Carcinoma with Extensive Urothelial “Eddy” Formation (pUNC-eUEF): A Distinct Morphologic Pattern with Low Risk for Progression

Mi-sung Kim, Jae Y Ro, Yong Mee Cho. University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea; The Methodist Hospital and Weill Medical College of Cornell University, Houston, TX

Background: Urothelial carcinoma (UC) is the most common urinary bladder tumor with variable clinical outcome. We encountered papillary urothelial neoplasm of lower malignant potential (PUNLMP) and UC showing extensive urothelial “eddy” formation (pUNC-eUEF), superficially resemble to squamous eddy seen in inverted follicular keratosis of the skin, of which clinicopathologic features have not been reported yet.
Design: Among 756 patients that underwent transurethral resection of bladder tumor at Asan Medical Center, Seoul, Korea from 1996 to 2006, 10 cases demonstrated pUNC-eUEF, in which their clinicopathologic features and immunoprofile were analyzed. As control groups for comparison of immunohistochemical staining results, 22 cases of classic UC matched for stage and grade of pUNC-eUEF, 9 cases of UC with squamous differentiation (UC-Sq), and 9 cases of squamous cell carcinoma of urinary bladder (SqCC-UB) were included.
Results: All pUNC-eUEF were male with a mean age of 65.4 years (range, 52∼79years). pUNC-eUEF consisted sheets or nests of large polygonal cells with prominent whirling pattern and intercellular bridges without evidence of keratinization. They were graded as PUNLMP (one case), low grade UC (eight) and high grade UC (one). All but one presented with non-invasive tumors (Ta) with only one case invaded subepithelial connective tissue (T1). pUNC-eUEF revealed immunoprofile of cytokeratin 7 and 20, p63, uroplakin-3, E2F1, D2-40, p53, and prostate acid phosphatase similar to UC rather than UC-Sq or SqCC-UB with the lowest Ki-67 labeling index (mean, 1.6 %), compared to the control groups. During the mean follow-up of 73 months, three cases of pUNC-eUEF (3 cases of low grade UC) were recurred. However, none progressed into muscle-invasive tumor or died of the disease.
Conclusions: This study suggests that pUNC-eUEF is a rare unique morphologic variant of UC with indolent clinical course. Further studies are required to better define the clinicopathologic parameters of this variant.
Category: Genitourinary (including renal tumors)

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 141, Wednesday Afternoon


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