[774] Distinctive Inmunohistochemical Profiles of Penile Intraepithelial Lesions – A Study of 74 Cases.

Alcides Chaux, Rolf Pfannl, Ingrid M Rodriguez, Jose E Barreto, Elsa F Velazquez, George J Netto, Antonio L Cubilla. Johns Hopkins University, Baltimore, MD; Tufts Medical Center, Boston, MA; Instituto de Patología e Investigación, Asunción, Paraguay; Caris Life Sciences, Boston, MA

Background: A new nomenclature of penile precancerous lesions have been proposed taking into consideration morphological and etiological factors. It is important to separate differentiated, HPV-unrelated penile intraepithelial neoplasia (PeIN) from nondifferentiated, HPV-related warty and basaloid PeIN.
Design: In order to determine the value of inmunohistochemical stains in the differential diagnosis and classification of PeIN 74 lesions classified as squamous hyperplasia (18 cases), differentiated (37 cases), basaloid (15 cases), and warty PeINs (4 cases) were pathologically evaluated using immunohistochemistry for p16INK4a, p53, and Ki67 expression. p16INK4a positivity required continuous, full thickness, nuclear and cytoplasmic stain in all epithelial cells. Intraepithelial lesions exhibiting p53 and Ki67 suprabasal or full thickenss nuclear staining were considered as positive.
Results: Results are depicted in Tables 1 and 2.

Table 1

	SH (%)	DPeIN (%)	BPeIN (%)	WPeIN (%)
p16INK4a+	0 (0)	2 (5)	14 (93)	4 (100)
p53 +	1 (6)	16 (43)	6 (43)	4 (100)
Ki67 +	8 (47)	28 (90)	15 (100)	4 (100)

Table 2: Profiles of immunoexpression

	p16INK4a	p53	Ki67
SH	Negative	Negative	Pos or Neg
DPeIN	Negative	Pos or Neg	Positive
W/BPeIN	Positive	Pos or Neg	Positive

Conclusions: p16INK4a distinguished SH and DPeIN from W/BPeIN while p53 can be used to separate SH from DPeIN and W/BPeIN. Ki67 is usually positive in DPeIN and W/BPeIN. The immunohistochemical profiles of penile precancerous lesions are distinctive and useful in the classification and differential diagnosis of PeIN.
Category: Genitourinary (including renal tumors)

Tuesday, March 1, 2011 1:00 PM

Poster Session IV # 92, Tuesday Afternoon