[919] p63 Imunohistochemistry in Histologic Variants of Urothelial Cell Carcinoma

Jeremy Klapper, Guang-Qian Xiao, Pamela D Unger. The Mount Sinai Medical Center, New York, NY

Background: Urothelial carcinoma (UC) occurs in a variety of histologic subtypes. p63, a member of the p53 family of transcription factors, is one of the most commonly used urothelial markers. There has been no prior systematic study regarding p63 immunohistochemical expression in histologic variants of UC.
Design: A total of 41 invasive UCs of different morphologic variants collected at our institution were stained with p63 monoclonal antibody (BioGenex, San Ramon, CA). Among the 41 UCs, 22 were of one morphologic variant and 19 contained more than one morphologic variant. For cases with more than one morphologic variant, each individual variant was counted as a separate event. In addition to p63, the two plasmacytoid UC cases were also stained with CD138 antibody (BioGenex, San Ramon, CA). Positive immunostaining was defined as uniform nuclear reactivity for p63 and cytoplasmic membrane staining for CD138.
Results: The results of p63 immunostaining are summarized in the table.

Histologic Variantp63 positive cases/Total cases
Clear cell5/5
Small cell/neuroendocrine2/2
Signet ring0/2

Micropapillary, glandular and signet ring cell UCs were consistently negative for p63. Of the two rhabdoid variant cases, one was negative for p63. All other variants and conventional UC cases were consistently reactive with p63. The two cases of plasmacytoid UC were also positive for CD138; however, the coexisting conventional UC, carcinoma in-situ and normal urothelium in these same cases were also strongly positive for CD138.
Conclusions: The results of this study indicate that p63 is a sensitive marker for most UC variants, with the exception of the micropapillary, glandular, and signet ring cell variants, which were consistently negative for p63. Awareness of this exception is of importance, especially in the evaluation of metastatic disease possibly arising from urinary tract. Although CD138 has been reported as a marker for plasmacytoid UC, our preliminary study demonstrated strong staining for CD138 in conventional UC as well as benign urothelium, which has not been previously documented. This preliminary data indicates that CD138 may not be specific for plasmacytoid UC, and should not be used in isolation to determine or characterize this variant.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 145, Monday Morning


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