[882] Distinctive Immunohistochemical Profile of the Penile Distal Urethra

Jeong S Han, George J Netto, Antonio L Cubilla, Stephen Lee, Nilda Gonzalez-Roibon, Rajni Sharma, Alcides Chaux. Johns Hopkins University, Baltimore, MD; Instituto de Patologia e Investigacion, Asuncion, Paraguay

Background: The true nature of the epithelium covering the penile distal urethra remains undefined. Some authors argue that, given its purported embryogenesis and pathology, the epithelium of the distal urethra would be more closely related to a squamous epithelium than to urothelium. Herein, we evaluate a panel of stains routinely used as markers of urothelial differentiation.
Design: Eleven total penectomies performed for squamous cell carcinoma of the glans were selected based on the presence of intact distal urethra in the tissue blocks. In all cases, the distal urethral mucosa was histologically unremarkable and uninvolved by tumor. Standard immunohistochemistry for CK7, CK20, thrombomodulin, p63, and GATA3 (BioCare, GATA3 clone L50-823) was performed.
Results: In all cases, 2 distinctive cell layers were observed in the epithelial lining of the distal urethra. The superficial layer was composed of a single file of tall columnar cells with clear cytoplasm and conspicuous cell borders. Stratified cubical cells with scant cytoplasm and undefined cell borders were observed underlying the superficial columnar layer. All distal urethral sections were negative for CK20 and thrombomodulin. Staining for CK7 was strong and diffuse in the superficial columnar cells, and negative to weak in the underlying layers in all cases. p63 displayed an inverse pattern of expression, with absence of staining in the superficial columnar cells, and strong and diffuse positivity in the underlying layers. With the exception of 1 case, GATA3 staining was observed transmucosally in all distal urethral sections.
Conclusions: The epithelium of the distal urethral mucosa is distinctive, morphologically and immunohistochemically. It is composed of 2 cell layers, a superficial columnar simple epithelium (CK7+/p63-/GATA3+), and an underlying stratified epithelium composed of cubical cells (CK7-/p63+/GATA3+).
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 1:00 PM

Poster Session II # 144, Monday Afternoon


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